restructured the project to comply community guideline, for others check release note

.github/workflows/docker-image.yml

@@ -130,18 +130,3 @@ jobs:
               run: |
                   docker tag ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }} ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
                   docker push ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
-    scan:
-        runs-on: ubuntu-latest
-        needs:
-            - merge
-        steps:
-            - name: Scan Image with Trivy
-              uses: aquasecurity/trivy-action@0.20.0
-              with:
-                  image-ref: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
-                  format: "sarif"
-                  output: "trivy-results.sarif"
-            - name: Upload Trivy SARIF Report
-              uses: github/codeql-action/upload-sarif@v3
-              with:
-                  sarif_file: "trivy-results.sarif"

.gitignore

@@ -3,8 +3,7 @@ compose.yml
 config*/
 certs*/
 bin/
-
-templates/codemirror/
+error_pages/
 
 logs/
 log/
@@ -13,7 +12,8 @@ log/
 
 go.work.sum
 
-!src/**/
+!cmd/**/
+!internal/**/
 
 todo.md
 

Dockerfile

@@ -5,7 +5,7 @@ RUN apk add --no-cache tzdata
 WORKDIR /src
 
 # Only copy go.mod and go.sum initially for better caching
-COPY src/go.mod src/go.sum ./
+COPY go.mod go.sum /src
 
 # Utilize build cache
 RUN --mount=type=cache,target="/go/pkg/mod" \
@@ -16,8 +16,10 @@ ENV GOCACHE=/root/.cache/go-build
 # Build the application with better caching
 RUN --mount=type=cache,target="/go/pkg/mod" \
     --mount=type=cache,target="/root/.cache/go-build" \
-    --mount=type=bind,src=src,dst=/src \
-    CGO_ENABLED=0 GOOS=linux go build -ldflags '-w -s' -pgo=auto -o /go-proxy .
+    --mount=type=bind,src=cmd,dst=/src/cmd \
+    --mount=type=bind,src=internal,dst=/src/internal \
+    CGO_ENABLED=0 GOOS=linux go build -ldflags '-w -s' -pgo=auto -o /app/go-proxy ./cmd && \
+    mkdir /app/error_pages /app/certs
 
 # Stage 2: Final image
 FROM scratch
@@ -28,7 +30,7 @@ LABEL maintainer="yusing@6uo.me"
 COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo
 
 # copy binary
-COPY --from=builder /go-proxy /app/
+COPY --from=builder /app /
 
 # copy schema directory
 COPY schema/ /app/schema/

Makefile

@@ -1,3 +1,5 @@
+BUILD_FLAG ?= -s -w
+
 .PHONY: all setup build test up restart logs get debug run archive repush rapid-crash debug-list-containers
 
 all: debug
@@ -10,10 +12,10 @@ setup:
 build:
 	mkdir -p bin
 	CGO_ENABLED=0 GOOS=linux \
-		go build -ldflags '${BUILD_FLAG}' -pgo=auto -o bin/go-proxy github.com/yusing/go-proxy
+		go build -ldflags '${BUILD_FLAG}' -pgo=auto -o bin/go-proxy ./cmd
 
 test:
-	go test ./src/...
+	go test ./internal/...
 
 up:
 	docker compose up -d
@@ -25,13 +27,13 @@ logs:
 	docker compose logs -f
 
 get:
-	cd src && go get -u && go mod tidy && cd ..
+	cd cmd && go get -u && go mod tidy && cd ..
 
 debug:
-	make build && sudo GOPROXY_DEBUG=1 bin/go-proxy
+	make BUILD_FLAG="" build && sudo GOPROXY_DEBUG=1 bin/go-proxy
 
 run:
-	BUILD_FLAG="-s -w" make build && sudo bin/go-proxy
+	make build && sudo bin/go-proxy
 
 archive:
 	git archive HEAD -o ../go-proxy-$$(date +"%Y%m%d%H%M").zip

README.md

@@ -40,6 +40,8 @@ A lightweight, easy-to-use, and [performant](docs/benchmark_result.md) reverse p
 -   Auto hot-reload on container state / config file changes
 -   **idlesleeper**: stop containers on idle, wake it up on traffic _(optional, see [showcase](#idlesleeper))_
 -   HTTP(s) reserve proxy
+-   [HTTP middleware support](docs/middlewares.md) _(experimental)_
+-   [Custom error pages support](docs/middlewares.md#custom-error-pages)
 -   TCP and UDP port forwarding
 -   Web UI for configuration and monitoring (See [screenshots](https://github.com/yusing/go-proxy-frontend?tab=readme-ov-file#screenshots))
 -   Supports linux/amd64, linux/arm64, linux/arm/v7, linux/arm/v6 multi-platform

cmd/main.go

@@ -16,23 +16,24 @@ import (
 	"time"
 
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/api"
-	apiUtils "github.com/yusing/go-proxy/api/v1/utils"
-	"github.com/yusing/go-proxy/common"
-	"github.com/yusing/go-proxy/config"
-	"github.com/yusing/go-proxy/docker"
-	"github.com/yusing/go-proxy/docker/idlewatcher"
-	E "github.com/yusing/go-proxy/error"
-	R "github.com/yusing/go-proxy/route"
-	"github.com/yusing/go-proxy/server"
-	F "github.com/yusing/go-proxy/utils/functional"
+	"github.com/yusing/go-proxy/internal"
+	"github.com/yusing/go-proxy/internal/api"
+	apiUtils "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/config"
+	"github.com/yusing/go-proxy/internal/docker"
+	"github.com/yusing/go-proxy/internal/docker/idlewatcher"
+	E "github.com/yusing/go-proxy/internal/error"
+	R "github.com/yusing/go-proxy/internal/route"
+	"github.com/yusing/go-proxy/internal/server"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 func main() {
 	args := common.GetArgs()
 
 	if args.Command == common.CommandSetup {
-		Setup()
+		internal.Setup()
 		return
 	}
 

docs/middlewares.md

@@ -8,6 +8,7 @@
   - [Table of content](#table-of-content)
   - [Available middlewares](#available-middlewares)
     - [Redirect http](#redirect-http)
+    - [Custom error pages](#custom-error-pages)
     - [Modify request or response](#modify-request-or-response)
       - [Set headers](#set-headers)
       - [Add headers](#add-headers)
@@ -48,6 +49,56 @@ server {
 
 [🔼Back to top](#table-of-content)
 
+### Custom error pages
+
+To enable custom error pages, mount a folder containing your `html`, `js`, `css` files to `/app/error_pages` of _go-proxy_ container **(subfolders are ignored, please place all files in root directory)**
+
+Any path under `error_pages` directory (e.g. `href` tag), should starts with `/$gperrorpage/`
+
+Example:
+```html
+<html>
+<head>
+    <title>404 Not Found</title>
+    <link type="text/css" rel="stylesheet" href="/$gperrorpage/style.css" />
+</head>
+<body>
+    ...
+</body>
+</html>
+```
+
+Hot-reloading is **supported**, you can **edit**, **rename** or **delete** files **without restarting**. Changes will be reflected after page reload
+
+Error page will be served if:
+-   status code is not in range of 200 to 300
+-   content type is `text/html`, `application/xhtml+xml` or `text/plain`
+
+Error page will be served:
+
+- from file `<statusCode>.html` if exists
+- otherwise from `404.html`
+- if they don't exist, original response will be served
+
+```yaml
+# docker labels
+proxy.app1.middlewares.custom_error_page:
+
+# include file
+app1:
+  middlewares:
+    custom_error_page:
+```
+
+nginx equivalent:
+```nginx
+location / {
+    try_files $uri $uri/ /error_pages/404.html =404;
+}
+```
+
+[🔼Back to top](#table-of-content)
+
 ### Modify request or response
 
 ```yaml
@@ -89,6 +140,8 @@ location / {
 }
 ```
 
+[🔼Back to top](#table-of-content)
+
 #### Add headers
 
 ```yaml
@@ -114,6 +167,8 @@ location / {
 }
 ```
 
+[🔼Back to top](#table-of-content)
+
 #### Hide headers
 
 ```yaml
@@ -171,6 +226,8 @@ app1:
       set_x_forwarded:
 ```
 
+[🔼Back to top](#table-of-content)
+
 ### Forward Authorization header (experimental)
 
 Fields:
@@ -226,6 +283,8 @@ http:
             - session_id
 ```
 
+[🔼Back to top](#table-of-content)
+
 ## Examples
 
 ### Authentik
@@ -242,4 +301,6 @@ services:
       proxy.authentik.middlewares.set_x_forwarded:
       proxy.authentik.middlewares.modify_request.add_headers: |
         Strict-Transport-Security: "max-age=63072000" always
-```
+```
+
+[🔼Back to top](#table-of-content)

go.mod

@@ -17,7 +17,7 @@ require (
 require (
 	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
-	github.com/cloudflare/cloudflare-go v0.105.0 // indirect
+	github.com/cloudflare/cloudflare-go v0.106.0 // indirect
 	github.com/containerd/log v0.1.0 // indirect
 	github.com/distribution/reference v0.6.0 // indirect
 	github.com/docker/go-connections v0.5.0 // indirect
@@ -39,9 +39,9 @@ require (
 	github.com/pkg/errors v0.9.1 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.55.0 // indirect
 	go.opentelemetry.io/otel v1.30.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.30.0 // indirect
 	go.opentelemetry.io/otel/metric v1.30.0 // indirect
-	go.opentelemetry.io/otel/sdk v1.24.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.30.0 // indirect
 	go.opentelemetry.io/otel/trace v1.30.0 // indirect
 	golang.org/x/crypto v0.27.0 // indirect
 	golang.org/x/mod v0.21.0 // indirect

go.sum

@@ -4,8 +4,8 @@ github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERo
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
 github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
 github.com/cenkalti/backoff/v4 v4.3.0/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
-github.com/cloudflare/cloudflare-go v0.105.0 h1:yu2IatITLZ4dw7/byzRrlE5DfUvtub0k9CHZ5zBlj90=
-github.com/cloudflare/cloudflare-go v0.105.0/go.mod h1:pfUQ4PIG4ISI0/Mmc21Bp86UnFU0ktmPf3iTgbSL+cM=
+github.com/cloudflare/cloudflare-go v0.106.0 h1:q41gC5Wc1nfi0D1ZhSHokWcd9mGMbqC7RE7qiP+qE00=
+github.com/cloudflare/cloudflare-go v0.106.0/go.mod h1:pfUQ4PIG4ISI0/Mmc21Bp86UnFU0ktmPf3iTgbSL+cM=
 github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
 github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -43,8 +43,10 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-querystring v1.1.0 h1:AnCroh3fv4ZBgVIf1Iwtovgjaw/GiKJo8M8yD/fhyJ8=
 github.com/google/go-querystring v1.1.0/go.mod h1:Kcdr2DB4koayq7X8pmAG4sNG59So17icRSOU623lUBU=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.19.0 h1:Wqo399gCIufwto+VfwCSvsnfGpF/w5E9CNxSwbpD6No=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.19.0/go.mod h1:qmOFXW2epJhM0qSnUUYpldc7gVz2KMQwJ/QYCDIa7XU=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.22.0 h1:asbCHRVmodnJTuQ3qamDwqVOIjwqUPTYmYuemVOx+Ys=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.22.0/go.mod h1:ggCgvZ2r7uOoQjOyu2Y1NhHmEPPzzuhWgcza5M1Ji1I=
 github.com/jarcoal/httpmock v1.3.0 h1:2RJ8GP0IIaWwcC9Fp2BmVi8Kog3v2Hn7VXM3fTd+nuc=
 github.com/jarcoal/httpmock v1.3.0/go.mod h1:3yb8rc4BI7TCBhFY8ng0gjuLKJNquuDNiPaZjnENuYg=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
@@ -91,18 +93,18 @@ go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.55.0 h1:ZIg3ZT/
 go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.55.0/go.mod h1:DQAwmETtZV00skUwgD6+0U89g80NKsJE3DCKeLLPQMI=
 go.opentelemetry.io/otel v1.30.0 h1:F2t8sK4qf1fAmY9ua4ohFS/K+FUuOPemHUIXHtktrts=
 go.opentelemetry.io/otel v1.30.0/go.mod h1:tFw4Br9b7fOS+uEao81PJjVMjW/5fvNCbpsDIXqP0pc=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.24.0 h1:t6wl9SPayj+c7lEIFgm4ooDBZVb01IhLB4InpomhRw8=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.24.0/go.mod h1:iSDOcsnSA5INXzZtwaBPrKp/lWu/V14Dd+llD0oI2EA=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0 h1:Xw8U6u2f8DK2XAkGRFV7BBLENgnTGX9i4rQRxJf+/vs=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0/go.mod h1:6KW1Fm6R/s6Z3PGXwSJN2K4eT6wQB3vXX6CVnYX9NmM=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.30.0 h1:lsInsfvhVIfOI6qHVyysXMNDnjO9Npvl7tlDPJFBVd4=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.30.0/go.mod h1:KQsVNh4OjgjTG0G6EiNi1jVpnaeeKsKMRwbLN+f1+8M=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.30.0 h1:umZgi92IyxfXd/l4kaDhnKgY8rnN/cZcF1LKc6I8OQ8=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.30.0/go.mod h1:4lVs6obhSVRb1EW5FhOuBTyiQhtRtAnnva9vD3yRfq8=
 go.opentelemetry.io/otel/metric v1.30.0 h1:4xNulvn9gjzo4hjg+wzIKG7iNFEaBMX00Qd4QIZs7+w=
 go.opentelemetry.io/otel/metric v1.30.0/go.mod h1:aXTfST94tswhWEb+5QjlSqG+cZlmyXy/u8jFpor3WqQ=
-go.opentelemetry.io/otel/sdk v1.24.0 h1:YMPPDNymmQN3ZgczicBY3B6sf9n62Dlj9pWD3ucgoDw=
-go.opentelemetry.io/otel/sdk v1.24.0/go.mod h1:KVrIYw6tEubO9E96HQpcmpTKDVn9gdv35HoYiQWGDFg=
+go.opentelemetry.io/otel/sdk v1.30.0 h1:cHdik6irO49R5IysVhdn8oaiR9m8XluDaJAs4DfOrYE=
+go.opentelemetry.io/otel/sdk v1.30.0/go.mod h1:p14X4Ok8S+sygzblytT1nqG98QG2KYKv++HE0LY/mhg=
 go.opentelemetry.io/otel/trace v1.30.0 h1:7UBkkYzeg3C7kQX8VAidWh2biiQbtAKjyIML8dQ9wmc=
 go.opentelemetry.io/otel/trace v1.30.0/go.mod h1:5EyKqTzzmyqB9bwtCCq6pDLktPK6fmGf/Dph+8VI02o=
-go.opentelemetry.io/proto/otlp v1.1.0 h1:2Di21piLrCqJ3U3eXGCTPHE9R8Nh+0uglSnOyxikMeI=
-go.opentelemetry.io/proto/otlp v1.1.0/go.mod h1:GpBHCBWiqvVLDqmHZsoMM3C5ySeKTC7ej/RNTae6MdY=
+go.opentelemetry.io/proto/otlp v1.3.1 h1:TrMUixzpM0yuc/znrFTP9MMRh8trP93mkCiDVeXrui0=
+go.opentelemetry.io/proto/otlp v1.3.1/go.mod h1:0X1WI4de4ZsLrrJNLAQbFeLCm3T7yBkR0XqQ7niQU+8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
@@ -148,14 +150,14 @@ golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8T
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/genproto v0.0.0-20240227224415-6ceb2ff114de h1:F6qOa9AZTYJXOUEr4jDysRDLrm4PHePlge4v4TGAlxY=
-google.golang.org/genproto/googleapis/api v0.0.0-20240311132316-a219d84964c2 h1:rIo7ocm2roD9DcFIX67Ym8icoGCKSARAiPljFhh5suQ=
-google.golang.org/genproto/googleapis/api v0.0.0-20240311132316-a219d84964c2/go.mod h1:O1cOfN1Cy6QEYr7VxtjOyP5AdAuR0aJ/MYZaaof623Y=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237 h1:NnYq6UN9ReLM9/Y01KWNOWyI5xQ9kbIms5GGJVwS/Yc=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237/go.mod h1:WtryC6hu0hhx87FDGxWCDptyssuo68sk10vYjF+T9fY=
-google.golang.org/grpc v1.63.1 h1:pNClQmvdlyNUiwFETOux/PYqfhmA7BrswEdGRnib1fA=
-google.golang.org/grpc v1.63.1/go.mod h1:WAX/8DgncnokcFUldAxq7GeB5DXHDbMF+lLvDomNkRA=
-google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
-google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+google.golang.org/genproto/googleapis/api v0.0.0-20240903143218-8af14fe29dc1 h1:hjSy6tcFQZ171igDaN5QHOw2n6vx40juYbC/x67CEhc=
+google.golang.org/genproto/googleapis/api v0.0.0-20240903143218-8af14fe29dc1/go.mod h1:qpvKtACPCQhAdu3PyQgV4l3LMXZEtft7y8QcarRsp9I=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1 h1:pPJltXNxVzT4pK9yD8vR9X75DaWYYmLGMsEvBfFQZzQ=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1/go.mod h1:UqMtugtsSgubUsoxbuAoiCXvqvErP7Gf0so0mK9tHxU=
+google.golang.org/grpc v1.66.1 h1:hO5qAXR19+/Z44hmvIM4dQFMSYX9XcWsByfoxutBpAM=
+google.golang.org/grpc v1.66.1/go.mod h1:s3/l6xSSCURdVfAnL+TqCNMyTDAGN6+lZeVxnZR128Y=
+google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
+google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

go.work

@@ -1,5 +0,0 @@
-go 1.22.0
-
-toolchain go1.23.1
-
-use ./src

internal/api/handler.go

@@ -0,0 +1,57 @@
+package api
+
+import (
+	"fmt"
+	"net/http"
+
+	v1 "github.com/yusing/go-proxy/internal/api/v1"
+	"github.com/yusing/go-proxy/internal/api/v1/error_page"
+	. "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/config"
+)
+
+type ServeMux struct{ *http.ServeMux }
+
+func NewServeMux() ServeMux {
+	return ServeMux{http.NewServeMux()}
+}
+
+func (mux ServeMux) HandleFunc(method, endpoint string, handler http.HandlerFunc) {
+	mux.ServeMux.HandleFunc(fmt.Sprintf("%s %s", method, endpoint), checkHost(handler))
+}
+
+func NewHandler(cfg *config.Config) http.Handler {
+	mux := NewServeMux()
+	mux.HandleFunc("GET", "/v1", v1.Index)
+	mux.HandleFunc("GET", "/v1/checkhealth", wrap(cfg, v1.CheckHealth))
+	mux.HandleFunc("HEAD", "/v1/checkhealth", wrap(cfg, v1.CheckHealth))
+	mux.HandleFunc("POST", "/v1/reload", wrap(cfg, v1.Reload))
+	mux.HandleFunc("GET", "/v1/list", wrap(cfg, v1.List))
+	mux.HandleFunc("GET", "/v1/list/{what}", wrap(cfg, v1.List))
+	mux.HandleFunc("GET", "/v1/file", v1.GetFileContent)
+	mux.HandleFunc("GET", "/v1/file/{filename}", v1.GetFileContent)
+	mux.HandleFunc("POST", "/v1/file/{filename}", v1.SetFileContent)
+	mux.HandleFunc("PUT", "/v1/file/{filename}", v1.SetFileContent)
+	mux.HandleFunc("GET", "/v1/stats", wrap(cfg, v1.Stats))
+	mux.HandleFunc("GET", "/v1/error_page", error_page.GetHandleFunc())
+	return mux
+}
+
+// allow only requests to API server with host matching common.APIHTTPAddr
+func checkHost(f http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Host != common.APIHTTPAddr {
+			Logger.Warnf("invalid request to API server with host: %s, expected: %s", r.Host, common.APIHTTPAddr)
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		f(w, r)
+	}
+}
+
+func wrap(cfg *config.Config, f func(cfg *config.Config, w http.ResponseWriter, r *http.Request)) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		f(cfg, w, r)
+	}
+}

internal/api/v1/checkhealth.go

@@ -5,9 +5,9 @@ import (
 	"net/http"
 	"strings"
 
-	U "github.com/yusing/go-proxy/api/v1/utils"
-	"github.com/yusing/go-proxy/config"
-	R "github.com/yusing/go-proxy/route"
+	U "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/config"
+	R "github.com/yusing/go-proxy/internal/route"
 )
 
 func CheckHealth(cfg *config.Config, w http.ResponseWriter, r *http.Request) {

internal/api/v1/error_page/error_page.go

@@ -0,0 +1,88 @@
+package error_page
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path"
+	"sync"
+
+	api "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	U "github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
+	W "github.com/yusing/go-proxy/internal/watcher"
+	"github.com/yusing/go-proxy/internal/watcher/events"
+)
+
+const errPagesBasePath = common.ErrorPagesBasePath
+
+var setup = sync.OnceFunc(func() {
+	dirWatcher = W.NewDirectoryWatcher(context.Background(), errPagesBasePath)
+	loadContent()
+	go watchDir()
+})
+
+func GetStaticFile(filename string) ([]byte, bool) {
+	return fileContentMap.Load(filename)
+}
+
+// try <statusCode>.html -> 404.html -> not ok
+func GetErrorPageByStatus(statusCode int) (content []byte, ok bool) {
+	content, ok = fileContentMap.Load(fmt.Sprintf("%d.html", statusCode))
+	if !ok && statusCode != 404 {
+		return fileContentMap.Load("404.html")
+	}
+	return
+}
+
+func loadContent() {
+	files, err := U.ListFiles(errPagesBasePath, 0)
+	if err != nil {
+		api.Logger.Error(err)
+		return
+	}
+	for _, file := range files {
+		if fileContentMap.Has(file) {
+			continue
+		}
+		content, err := os.ReadFile(file)
+		if err != nil {
+			api.Logger.Errorf("failed to read error page resource %s: %s", file, err)
+			continue
+		}
+		file = path.Base(file)
+		api.Logger.Infof("error page resource %s loaded", file)
+		fileContentMap.Store(file, content)
+	}
+}
+
+func watchDir() {
+	eventCh, errCh := dirWatcher.Events(context.Background())
+	for {
+		select {
+		case event, ok := <-eventCh:
+			if !ok {
+				return
+			}
+			filename := event.ActorName
+			switch event.Action {
+			case events.ActionFileWritten:
+				fileContentMap.Delete(filename)
+				loadContent()
+			case events.ActionFileDeleted:
+				fileContentMap.Delete(filename)
+				api.Logger.Infof("error page resource %s deleted", filename)
+			case events.ActionFileRenamed:
+				api.Logger.Infof("error page resource %s deleted", filename)
+				fileContentMap.Delete(filename)
+				loadContent()
+			}
+		case err := <-errCh:
+			api.Logger.Errorf("error watching error page directory: %s", err)
+		}
+	}
+}
+
+var dirWatcher W.Watcher
+var fileContentMap = F.NewMapOf[string, []byte]()

internal/api/v1/error_page/http_handler.go

@@ -0,0 +1,25 @@
+package error_page
+
+import "net/http"
+
+func GetHandleFunc() http.HandlerFunc {
+	setup()
+	return serveHTTP
+}
+
+func serveHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	if r.URL.Path == "/" {
+		http.Error(w, "invalid path", http.StatusNotFound)
+		return
+	}
+	content, ok := fileContentMap.Load(r.URL.Path)
+	if !ok {
+		http.Error(w, "404 not found", http.StatusNotFound)
+		return
+	}
+	w.Write(content)
+}

internal/api/v1/file.go

@@ -6,10 +6,11 @@ import (
 	"os"
 	"path"
 
-	U "github.com/yusing/go-proxy/api/v1/utils"
-	"github.com/yusing/go-proxy/common"
-	"github.com/yusing/go-proxy/config"
-	"github.com/yusing/go-proxy/proxy/provider"
+	U "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/config"
+	E "github.com/yusing/go-proxy/internal/error"
+	"github.com/yusing/go-proxy/internal/proxy/provider"
 )
 
 func GetFileContent(w http.ResponseWriter, r *http.Request) {
@@ -37,14 +38,15 @@ func SetFileContent(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	var validateErr E.NestedError
 	if filename == common.ConfigFileName {
-		err = config.Validate(content).Error()
+		validateErr = config.Validate(content)
 	} else {
-		err = provider.Validate(content).Error()
+		validateErr = provider.Validate(content)
 	}
 
-	if err != nil {
-		U.HandleErr(w, r, err, http.StatusBadRequest)
+	if validateErr != nil {
+		U.RespondJson(w, validateErr.JSONObject(), http.StatusBadRequest)
 		return
 	}
 

internal/api/v1/list.go

@@ -5,10 +5,9 @@ import (
 	"net/http"
 	"os"
 
-	"github.com/yusing/go-proxy/common"
-	"github.com/yusing/go-proxy/config"
-
-	U "github.com/yusing/go-proxy/api/v1/utils"
+	U "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/config"
 )
 
 func List(cfg *config.Config, w http.ResponseWriter, r *http.Request) {
@@ -38,7 +37,7 @@ func listRoutes(cfg *config.Config, w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	if err := U.RespondJson(routes, w); err != nil {
+	if err := U.RespondJson(w, routes); err != nil {
 		U.HandleErr(w, r, err)
 	}
 }

internal/api/v1/reload.go

@@ -0,0 +1,16 @@
+package v1
+
+import (
+	"net/http"
+
+	U "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/config"
+)
+
+func Reload(cfg *config.Config, w http.ResponseWriter, r *http.Request) {
+	if err := cfg.Reload(); err != nil {
+		U.RespondJson(w, err.JSONObject(), http.StatusInternalServerError)
+	} else {
+		w.WriteHeader(http.StatusOK)
+	}
+}

internal/api/v1/stats.go

@@ -3,10 +3,10 @@ package v1
 import (
 	"net/http"
 
-	U "github.com/yusing/go-proxy/api/v1/utils"
-	"github.com/yusing/go-proxy/config"
-	"github.com/yusing/go-proxy/server"
-	"github.com/yusing/go-proxy/utils"
+	U "github.com/yusing/go-proxy/internal/api/v1/utils"
+	"github.com/yusing/go-proxy/internal/config"
+	"github.com/yusing/go-proxy/internal/server"
+	"github.com/yusing/go-proxy/internal/utils"
 )
 
 func Stats(cfg *config.Config, w http.ResponseWriter, r *http.Request) {
@@ -14,7 +14,7 @@ func Stats(cfg *config.Config, w http.ResponseWriter, r *http.Request) {
 		"proxies": cfg.Statistics(),
 		"uptime":  utils.FormatDuration(server.GetProxyServer().Uptime()),
 	}
-	if err := U.RespondJson(stats, w); err != nil {
+	if err := U.RespondJson(w, stats); err != nil {
 		U.HandleErr(w, r, err)
 	}
 }

internal/api/v1/utils/error.go

@@ -6,12 +6,14 @@ import (
 	"net/http"
 
 	"github.com/sirupsen/logrus"
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
+var Logger = logrus.WithField("module", "api")
+
 func HandleErr(w http.ResponseWriter, r *http.Request, origErr error, code ...int) {
 	err := E.From(origErr).Subjectf("%s %s", r.Method, r.URL)
-	logrus.WithField("module", "api").Error(err)
+	Logger.Error(err)
 	if len(code) > 0 {
 		http.Error(w, err.String(), code[0])
 		return

internal/api/v1/utils/health_check.go

@@ -0,0 +1,33 @@
+package utils
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/common"
+)
+
+func IsSiteHealthy(url string) bool {
+	// try HEAD first
+	// if HEAD is not allowed, try GET
+	resp, err := httpClient.Head(url)
+	if resp != nil {
+		resp.Body.Close()
+	}
+	if err != nil && resp != nil && resp.StatusCode == http.StatusMethodNotAllowed {
+		_, err = httpClient.Get(url)
+	}
+	if resp != nil {
+		resp.Body.Close()
+	}
+	return err == nil
+}
+
+func IsStreamHealthy(scheme, address string) bool {
+	conn, err := net.DialTimeout(scheme, address, common.DialTimeout)
+	if err != nil {
+		return false
+	}
+	conn.Close()
+	return true
+}

internal/api/v1/utils/http_client.go

@@ -0,0 +1,23 @@
+package utils
+
+import (
+	"crypto/tls"
+	"net"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/common"
+)
+
+var httpClient = &http.Client{
+	Timeout: common.ConnectionTimeout,
+	Transport: &http.Transport{
+		Proxy:             http.ProxyFromEnvironment,
+		DisableKeepAlives: true,
+		ForceAttemptHTTP2: true,
+		DialContext: (&net.Dialer{
+			Timeout:   common.DialTimeout,
+			KeepAlive: common.KeepAlive, // this is different from DisableKeepAlives
+		}).DialContext,
+		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+	},
+}

internal/api/v1/utils/localhost.go

@@ -0,0 +1,31 @@
+package utils
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
+)
+
+func ReloadServer() E.NestedError {
+	resp, err := httpClient.Post(fmt.Sprintf("%s/v1/reload", common.APIHTTPURL), "", nil)
+	if err != nil {
+		return E.From(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		failure := E.Failure("server reload").Extraf("status code: %v", resp.StatusCode)
+		b, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return failure.Extraf("unable to read response body: %s", err)
+		}
+		reloadErr, ok := E.FromJSON(b)
+		if ok {
+			return E.Join("reload success, but server returned error", reloadErr)
+		}
+		return failure.Extraf("unable to read response body")
+	}
+	return nil
+}

internal/api/v1/utils/utils.go

@@ -5,9 +5,12 @@ import (
 	"net/http"
 )
 
-func RespondJson(data any, w http.ResponseWriter) error {
+func RespondJson(w http.ResponseWriter, data any, code ...int) error {
+	if len(code) > 0 {
+		w.WriteHeader(code[0])
+	}
 	w.Header().Set("Content-Type", "application/json")
-	j, err := json.Marshal(data)
+	j, err := json.MarshalIndent(data, "", "  ")
 	if err != nil {
 		return err
 	} else {

internal/autocert/config.go

@@ -7,8 +7,8 @@ import (
 
 	"github.com/go-acme/lego/v4/certcrypto"
 	"github.com/go-acme/lego/v4/lego"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
 )
 
 type Config M.AutoCertConfig

internal/autocert/provider.go

@@ -14,9 +14,9 @@ import (
 	"github.com/go-acme/lego/v4/challenge"
 	"github.com/go-acme/lego/v4/lego"
 	"github.com/go-acme/lego/v4/registration"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
-	U "github.com/yusing/go-proxy/utils"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
+	U "github.com/yusing/go-proxy/internal/utils"
 )
 
 type Provider struct {

internal/autocert/provider_test/ovh_test.go

@@ -4,8 +4,8 @@ import (
 	"testing"
 
 	"github.com/go-acme/lego/v4/providers/dns/ovh"
-	U "github.com/yusing/go-proxy/utils"
-	. "github.com/yusing/go-proxy/utils/testing"
+	U "github.com/yusing/go-proxy/internal/utils"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 	"gopkg.in/yaml.v3"
 )
 

internal/autocert/setup.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"os"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 func (p *Provider) Setup(ctx context.Context) (err E.NestedError) {

internal/common/args.go

@@ -4,7 +4,7 @@ import (
 	"flag"
 
 	"github.com/sirupsen/logrus"
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type Args struct {

internal/common/constants.go

@@ -7,7 +7,7 @@ import (
 const (
 	ConnectionTimeout = 5 * time.Second
 	DialTimeout       = 3 * time.Second
-	KeepAlive         = 5 * time.Second
+	KeepAlive         = 60 * time.Second
 )
 
 // file, folder structure
@@ -30,6 +30,10 @@ const (
 	ComposeExampleFileName = "compose.example.yml"
 )
 
+const (
+	ErrorPagesBasePath = "error_pages"
+)
+
 const DockerHostFromEnv = "$DOCKER_HOST"
 
 const (

internal/common/env.go

@@ -0,0 +1,55 @@
+package common
+
+import (
+	"fmt"
+	"net"
+	"os"
+
+	"github.com/sirupsen/logrus"
+	U "github.com/yusing/go-proxy/internal/utils"
+)
+
+var (
+	NoSchemaValidation = GetEnvBool("GOPROXY_NO_SCHEMA_VALIDATION")
+	IsDebug            = GetEnvBool("GOPROXY_DEBUG")
+
+	ProxyHTTPAddr,
+	ProxyHTTPHost,
+	ProxyHTTPPort,
+	ProxyHTTPURL = GetAddrEnv("GOPROXY_HTTP_ADDR", ":80", "http")
+
+	ProxyHTTPSAddr,
+	ProxyHTTPSHost,
+	ProxyHTTPSPort,
+	ProxyHTTPSURL = GetAddrEnv("GOPROXY_HTTPS_ADDR", ":443", "https")
+
+	APIHTTPAddr,
+	APIHTTPHost,
+	APIHTTPPort,
+	APIHTTPURL = GetAddrEnv("GOPROXY_API_ADDR", "127.0.0.1:8888", "http")
+)
+
+func GetEnvBool(key string) bool {
+	return U.ParseBool(os.Getenv(key))
+}
+
+func GetEnv(key, defaultValue string) string {
+	value, ok := os.LookupEnv(key)
+	if !ok {
+		value = defaultValue
+	}
+	return value
+}
+
+func GetAddrEnv(key, defaultValue, scheme string) (addr, host, port, fullURL string) {
+	addr = GetEnv(key, defaultValue)
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		logrus.Fatalf("Invalid address: %s", addr)
+	}
+	if host == "" {
+		host = "localhost"
+	}
+	fullURL = fmt.Sprintf("%s://%s:%s", scheme, host, port)
+	return
+}

internal/config/config.go

@@ -5,16 +5,16 @@ import (
 	"os"
 
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/autocert"
-	"github.com/yusing/go-proxy/common"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
-	PR "github.com/yusing/go-proxy/proxy/provider"
-	R "github.com/yusing/go-proxy/route"
-	U "github.com/yusing/go-proxy/utils"
-	F "github.com/yusing/go-proxy/utils/functional"
-	W "github.com/yusing/go-proxy/watcher"
-	"github.com/yusing/go-proxy/watcher/events"
+	"github.com/yusing/go-proxy/internal/autocert"
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
+	PR "github.com/yusing/go-proxy/internal/proxy/provider"
+	R "github.com/yusing/go-proxy/internal/route"
+	U "github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
+	W "github.com/yusing/go-proxy/internal/watcher"
+	"github.com/yusing/go-proxy/internal/watcher/events"
 	"gopkg.in/yaml.v3"
 )
 
@@ -45,7 +45,7 @@ func Load() E.NestedError {
 		value:          M.DefaultConfig(),
 		proxyProviders: F.NewMapOf[string, *PR.Provider](),
 		l:              logrus.WithField("module", "config"),
-		watcher:        W.NewFileWatcher(common.ConfigFileName),
+		watcher:        W.NewConfigFileWatcher(common.ConfigFileName),
 		reloadReq:      make(chan struct{}, 1),
 	}
 	return instance.load()
@@ -116,8 +116,9 @@ func (cfg *Config) WatchChanges() {
 			case <-cfg.watcherCtx.Done():
 				return
 			case event := <-eventCh:
-				if event.Action == events.ActionFileDeleted {
-					cfg.stopProviders()
+				if event.Action == events.ActionFileDeleted || event.Action == events.ActionFileRenamed {
+					cfg.l.Error("config file deleted or renamed, ignoring...")
+					continue
 				} else {
 					cfg.reloadReq <- struct{}{}
 				}

internal/config/query.go

@@ -1,11 +1,11 @@
 package config
 
 import (
-	M "github.com/yusing/go-proxy/models"
-	PR "github.com/yusing/go-proxy/proxy/provider"
-	R "github.com/yusing/go-proxy/route"
-	U "github.com/yusing/go-proxy/utils"
-	F "github.com/yusing/go-proxy/utils/functional"
+	M "github.com/yusing/go-proxy/internal/models"
+	PR "github.com/yusing/go-proxy/internal/proxy/provider"
+	R "github.com/yusing/go-proxy/internal/route"
+	U "github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 func (cfg *Config) DumpEntries() map[string]*M.RawEntry {

internal/docker/client.go

@@ -8,9 +8,9 @@ import (
 	"github.com/docker/cli/cli/connhelper"
 	"github.com/docker/docker/client"
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/common"
-	E "github.com/yusing/go-proxy/error"
-	F "github.com/yusing/go-proxy/utils/functional"
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 type Client struct {

internal/docker/client_info.go

@@ -8,7 +8,7 @@ import (
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/client"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type ClientInfo struct {

internal/docker/container.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 
 	"github.com/docker/docker/api/types"
-	U "github.com/yusing/go-proxy/utils"
+	U "github.com/yusing/go-proxy/internal/utils"
 )
 
 type Container struct {

internal/docker/idlewatcher/http.go

@@ -19,13 +19,7 @@ type templateData struct {
 
 //go:embed html/loading_page.html
 var loadingPage []byte
-var loadingPageTmpl = func() *template.Template {
-	tmpl, err := template.New("loading").Parse(string(loadingPage))
-	if err != nil {
-		panic(err)
-	}
-	return tmpl
-}()
+var loadingPageTmpl = template.Must(template.New("loading_page").Parse(string(loadingPage)))
 
 const (
 	htmlContentType = "text/html; charset=utf-8"

internal/docker/idlewatcher/round_trip.go

@@ -18,7 +18,10 @@ func (rt roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 
 func (w *watcher) roundTrip(origRoundTrip roundTripFunc, req *http.Request) (*http.Response, error) {
 	// wake the container
-	w.wakeCh <- struct{}{}
+	select {
+	case w.wakeCh <- struct{}{}:
+	default:
+	}
 
 	// target site is ready, passthrough
 	if w.ready.Load() {

internal/docker/idlewatcher/watcher.go

@@ -9,11 +9,11 @@ import (
 
 	"github.com/docker/docker/api/types/container"
 	"github.com/sirupsen/logrus"
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	P "github.com/yusing/go-proxy/proxy"
-	PT "github.com/yusing/go-proxy/proxy/fields"
-	W "github.com/yusing/go-proxy/watcher"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	P "github.com/yusing/go-proxy/internal/proxy"
+	PT "github.com/yusing/go-proxy/internal/proxy/fields"
+	W "github.com/yusing/go-proxy/internal/watcher"
 )
 
 type (

internal/docker/inspect.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"time"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 func (c Client) Inspect(containerID string) (Container, E.NestedError) {

internal/docker/label.go

@@ -4,9 +4,9 @@ import (
 	"reflect"
 	"strings"
 
-	E "github.com/yusing/go-proxy/error"
-	U "github.com/yusing/go-proxy/utils"
-	F "github.com/yusing/go-proxy/utils/functional"
+	E "github.com/yusing/go-proxy/internal/error"
+	U "github.com/yusing/go-proxy/internal/utils"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 /*

internal/docker/label_parser.go

@@ -3,7 +3,7 @@ package docker
 import (
 	"strings"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 	"gopkg.in/yaml.v3"
 )
 

internal/docker/label_parser_test.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"testing"
 
-	E "github.com/yusing/go-proxy/error"
-	. "github.com/yusing/go-proxy/utils/testing"
+	E "github.com/yusing/go-proxy/internal/error"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func makeLabel(namespace string, alias string, field string) string {

internal/docker/label_test.go

@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"testing"
 
-	U "github.com/yusing/go-proxy/utils"
-	. "github.com/yusing/go-proxy/utils/testing"
+	U "github.com/yusing/go-proxy/internal/utils"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestNestedLabel(t *testing.T) {

internal/error/builder_test.go

@@ -3,7 +3,7 @@ package error
 import (
 	"testing"
 
-	. "github.com/yusing/go-proxy/utils/testing"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestBuilderEmpty(t *testing.T) {

internal/error/error.go

@@ -1,6 +1,7 @@
 package error
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"strings"
@@ -13,6 +14,11 @@ type (
 		err     error
 		extras  []nestedError
 	}
+	jsonNestedError struct {
+		Subject string
+		Err     string
+		Extras  []jsonNestedError
+	}
 )
 
 func From(err error) NestedError {
@@ -22,6 +28,29 @@ func From(err error) NestedError {
 	return &nestedError{err: err}
 }
 
+func FromJSON(data []byte) (NestedError, bool) {
+	var j jsonNestedError
+	if err := json.Unmarshal(data, &j); err != nil {
+		return nil, false
+	}
+	if j.Err == "" {
+		return nil, false
+	}
+	extras := make([]nestedError, len(j.Extras))
+	for i, e := range j.Extras {
+		extra, ok := fromJSONObject(e)
+		if !ok {
+			return nil, false
+		}
+		extras[i] = *extra
+	}
+	return &nestedError{
+		subject: j.Subject,
+		err:     errors.New(j.Err),
+		extras:  extras,
+	}, true
+}
+
 // Check is a helper function that
 // convert (T, error) to (T, NestedError).
 func Check[T any](obj T, err error) (T, NestedError) {
@@ -157,6 +186,23 @@ func (ne NestedError) Subjectf(format string, args ...any) NestedError {
 	return ne
 }
 
+func (ne NestedError) JSONObject() jsonNestedError {
+	extras := make([]jsonNestedError, len(ne.extras))
+	for i, e := range ne.extras {
+		extras[i] = e.JSONObject()
+	}
+	return jsonNestedError{
+		Subject: ne.subject,
+		Err:     ne.err.Error(),
+		Extras:  extras,
+	}
+}
+
+func (ne NestedError) JSON() []byte {
+	b, _ := json.MarshalIndent(ne.JSONObject(), "", "  ")
+	return b
+}
+
 func (ne NestedError) NoError() bool {
 	return ne == nil
 }
@@ -169,6 +215,14 @@ func errorf(format string, args ...any) NestedError {
 	return From(fmt.Errorf(format, args...))
 }
 
+func fromJSONObject(obj jsonNestedError) (NestedError, bool) {
+	data, err := json.Marshal(obj)
+	if err != nil {
+		return nil, false
+	}
+	return FromJSON(data)
+}
+
 func (ne NestedError) withError(err NestedError) NestedError {
 	if ne != nil && err != nil {
 		ne.extras = append(ne.extras, *err)

internal/error/error_test.go

@@ -4,8 +4,8 @@ import (
 	"errors"
 	"testing"
 
-	. "github.com/yusing/go-proxy/error"
-	. "github.com/yusing/go-proxy/utils/testing"
+	. "github.com/yusing/go-proxy/internal/error"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestErrorIs(t *testing.T) {

internal/http/content_type.go

@@ -0,0 +1,32 @@
+package http
+
+import (
+	"mime"
+	"net/http"
+)
+
+type ContentType string
+
+func GetContentType(h http.Header) ContentType {
+	ct := h.Get("Content-Type")
+	if ct == "" {
+		return ""
+	}
+	ct, _, err := mime.ParseMediaType(ct)
+	if err != nil {
+		return ""
+	}
+	return ContentType(ct)
+}
+
+func (ct ContentType) IsHTML() bool {
+	return ct == "text/html" || ct == "application/xhtml+xml"
+}
+
+func (ct ContentType) IsJSON() bool {
+	return ct == "application/json"
+}
+
+func (ct ContentType) IsPlainText() bool {
+	return ct == "text/plain"
+}

internal/http/header_utils.go

@@ -1,15 +1,13 @@
-package middleware
+package http
 
 import (
 	"net/http"
 	"slices"
-
-	gpHTTP "github.com/yusing/go-proxy/http"
 )
 
-func removeHop(h Header) {
-	reqUpType := gpHTTP.UpgradeType(h)
-	gpHTTP.RemoveHopByHopHeaders(h)
+func RemoveHop(h http.Header) {
+	reqUpType := UpgradeType(h)
+	RemoveHopByHopHeaders(h)
 
 	if reqUpType != "" {
 		h.Set("Connection", "Upgrade")
@@ -19,7 +17,7 @@ func removeHop(h Header) {
 	}
 }
 
-func copyHeader(dst, src Header) {
+func CopyHeader(dst, src http.Header) {
 	for k, vv := range src {
 		for _, v := range vv {
 			dst.Add(k, v)
@@ -27,7 +25,7 @@ func copyHeader(dst, src Header) {
 	}
 }
 
-func filterHeaders(h Header, allowed []string) {
+func FilterHeaders(h http.Header, allowed []string) {
 	if allowed == nil {
 		return
 	}

internal/http/reverse_proxy_mod.go

@@ -10,6 +10,7 @@ package http
 // Copyright (c) 2024 yusing
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -129,20 +130,13 @@ type ReverseProxy struct {
 	// Response from the backend. It is called if the backend
 	// returns a response at all, with any HTTP status code.
 	// If the backend is unreachable, the optional ErrorHandler is
-	// called without any call to ModifyResponse.
+	// called before ModifyResponse.
 	//
 	// If ModifyResponse returns an error, ErrorHandler is called
 	// with its error value. If ErrorHandler is nil, its default
 	// implementation is used.
 	ModifyResponse func(*http.Response) error
 
-	// ErrorHandler is an optional function that handles errors
-	// reaching the backend or errors from ModifyResponse.
-	//
-	// If nil, the default is to log the provided error and return
-	// a 502 Status Bad Gateway response.
-	ErrorHandler func(http.ResponseWriter, *http.Request, error)
-
 	ServeHTTP http.HandlerFunc
 }
 
@@ -255,9 +249,11 @@ func copyHeader(dst, src http.Header) {
 	}
 }
 
-func (p *ReverseProxy) errorHandler(rw http.ResponseWriter, _ *http.Request, err error) {
-	logger.Errorf("http: proxy error: %s", err)
-	rw.WriteHeader(http.StatusBadGateway)
+func (p *ReverseProxy) errorHandler(rw http.ResponseWriter, r *http.Request, err error, writeHeader bool) {
+	logger.Errorf("http proxy to %s failed: %s", r.URL.String(), err)
+	if writeHeader {
+		rw.WriteHeader(http.StatusBadGateway)
+	}
 }
 
 // modifyResponse conditionally runs the optional ModifyResponse hook
@@ -268,7 +264,7 @@ func (p *ReverseProxy) modifyResponse(rw http.ResponseWriter, res *http.Response
 	}
 	if err := p.ModifyResponse(res); err != nil {
 		res.Body.Close()
-		p.errorHandler(rw, req, err)
+		p.errorHandler(rw, req, err, true)
 		return false
 	}
 	return true
@@ -324,7 +320,7 @@ func (p *ReverseProxy) serveHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	reqUpType := UpgradeType(outreq.Header)
 	if !IsPrint(reqUpType) {
-		p.errorHandler(rw, req, fmt.Errorf("client tried to switch to invalid protocol %q", reqUpType))
+		p.errorHandler(rw, req, fmt.Errorf("client tried to switch to invalid protocol %q", reqUpType), true)
 		return
 	}
 
@@ -384,8 +380,20 @@ func (p *ReverseProxy) serveHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	res, err := transport.RoundTrip(outreq)
 	if err != nil {
-		p.errorHandler(rw, outreq, err)
-		return
+		p.errorHandler(rw, outreq, err, false)
+		errMsg := err.Error()
+		res = &http.Response{
+			Status:        http.StatusText(http.StatusBadGateway),
+			StatusCode:    http.StatusBadGateway,
+			Proto:         outreq.Proto,
+			ProtoMajor:    outreq.ProtoMajor,
+			ProtoMinor:    outreq.ProtoMinor,
+			Header:        make(http.Header),
+			Body:          io.NopCloser(bytes.NewReader([]byte(errMsg))),
+			Request:       outreq,
+			ContentLength: int64(len(errMsg)),
+			TLS:           outreq.TLS,
+		}
 	}
 
 	// Deal with 101 Switching Protocols responses: (WebSocket, h2c, etc)
@@ -418,16 +426,9 @@ func (p *ReverseProxy) serveHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	_, err = io.Copy(rw, res.Body)
 	if err != nil {
-		defer res.Body.Close()
-		// note: removed
-		// Since we're streaming the response, if we run into an error all we can do
-		// is abort the request. Issue 23643: ReverseProxy should use ErrAbortHandler
-		// on read error while copying body.
-		// if !shouldPanicOnCopyError(req) {
-		// 	p.logf("suppressing panic for copyResponse error in test; copy error: %s", err)
-		// 	return
-		// }
-		panic(http.ErrAbortHandler)
+		p.errorHandler(rw, req, err, true)
+		res.Body.Close()
+		return
 	}
 	res.Body.Close() // close now, instead of defer, to populate res.Trailer
 
@@ -480,23 +481,23 @@ func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.R
 	reqUpType := UpgradeType(req.Header)
 	resUpType := UpgradeType(res.Header)
 	if !IsPrint(resUpType) { // We know reqUpType is ASCII, it's checked by the caller.
-		p.errorHandler(rw, req, fmt.Errorf("backend tried to switch to invalid protocol %q", resUpType))
+		p.errorHandler(rw, req, fmt.Errorf("backend tried to switch to invalid protocol %q", resUpType), true)
 	}
 	if !strings.EqualFold(reqUpType, resUpType) {
-		p.errorHandler(rw, req, fmt.Errorf("backend tried to switch protocol %q when %q was requested", resUpType, reqUpType))
+		p.errorHandler(rw, req, fmt.Errorf("backend tried to switch protocol %q when %q was requested", resUpType, reqUpType), true)
 		return
 	}
 
 	backConn, ok := res.Body.(io.ReadWriteCloser)
 	if !ok {
-		p.errorHandler(rw, req, fmt.Errorf("internal error: 101 switching protocols response with non-writable body"))
+		p.errorHandler(rw, req, fmt.Errorf("internal error: 101 switching protocols response with non-writable body"), true)
 		return
 	}
 
 	rc := http.NewResponseController(rw)
 	conn, brw, hijackErr := rc.Hijack()
 	if errors.Is(hijackErr, http.ErrNotSupported) {
-		p.errorHandler(rw, req, fmt.Errorf("can't switch protocols using non-Hijacker ResponseWriter type %T", rw))
+		p.errorHandler(rw, req, fmt.Errorf("can't switch protocols using non-Hijacker ResponseWriter type %T", rw), true)
 		return
 	}
 
@@ -513,7 +514,7 @@ func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.R
 	defer close(backConnCloseCh)
 
 	if hijackErr != nil {
-		p.errorHandler(rw, req, fmt.Errorf("hijack failed on protocol switch: %w", hijackErr))
+		p.errorHandler(rw, req, fmt.Errorf("hijack failed on protocol switch: %w", hijackErr), true)
 		return
 	}
 	defer conn.Close()
@@ -523,11 +524,11 @@ func (p *ReverseProxy) handleUpgradeResponse(rw http.ResponseWriter, req *http.R
 	res.Header = rw.Header()
 	res.Body = nil // so res.Write only writes the headers; we have res.Body in backConn above
 	if err := res.Write(brw); err != nil {
-		p.errorHandler(rw, req, fmt.Errorf("response write: %s", err))
+		p.errorHandler(rw, req, fmt.Errorf("response write: %s", err), true)
 		return
 	}
 	if err := brw.Flush(); err != nil {
-		p.errorHandler(rw, req, fmt.Errorf("response flush: %s", err))
+		p.errorHandler(rw, req, fmt.Errorf("response flush: %s", err), true)
 		return
 	}
 	errc := make(chan error, 1)

internal/http/status_code.go

@@ -0,0 +1,7 @@
+package http
+
+import "net/http"
+
+func IsSuccess(status int) bool {
+	return status >= http.StatusOK && status < http.StatusMultipleChoices
+}

internal/models/raw_entry.go

@@ -5,9 +5,9 @@ import (
 	"strconv"
 	"strings"
 
-	. "github.com/yusing/go-proxy/common"
-	D "github.com/yusing/go-proxy/docker"
-	F "github.com/yusing/go-proxy/utils/functional"
+	. "github.com/yusing/go-proxy/internal/common"
+	D "github.com/yusing/go-proxy/internal/docker"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 type (

internal/proxy/entry.go

@@ -5,10 +5,10 @@ import (
 	"net/url"
 	"time"
 
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
-	T "github.com/yusing/go-proxy/proxy/fields"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
+	T "github.com/yusing/go-proxy/internal/proxy/fields"
 )
 
 type (

internal/proxy/fields/headers.go

@@ -4,7 +4,7 @@ import (
 	"net/http"
 	"strings"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 func ValidateHTTPHeaders(headers map[string]string) (http.Header, E.NestedError) {

internal/proxy/fields/host.go

@@ -1,7 +1,7 @@
 package fields
 
 import (
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type Host string

internal/proxy/fields/path_mode.go

@@ -1,7 +1,7 @@
 package fields
 
 import (
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type PathMode string

internal/proxy/fields/path_pattern.go

@@ -3,7 +3,7 @@ package fields
 import (
 	"regexp"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type PathPattern string

internal/proxy/fields/path_pattern_test.go

@@ -3,8 +3,8 @@ package fields
 import (
 	"testing"
 
-	E "github.com/yusing/go-proxy/error"
-	U "github.com/yusing/go-proxy/utils/testing"
+	E "github.com/yusing/go-proxy/internal/error"
+	U "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 var validPatterns = []string{

internal/proxy/fields/port.go

@@ -3,7 +3,7 @@ package fields
 import (
 	"strconv"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type Port int

internal/proxy/fields/scheme.go

@@ -1,7 +1,7 @@
 package fields
 
 import (
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type Scheme string

internal/proxy/fields/signal.go

@@ -1,7 +1,7 @@
 package fields
 
 import (
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type Signal string

internal/proxy/fields/stop_method.go

@@ -1,7 +1,7 @@
 package fields
 
 import (
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type StopMethod string

internal/proxy/fields/stream_port.go

@@ -3,8 +3,8 @@ package fields
 import (
 	"strings"
 
-	"github.com/yusing/go-proxy/common"
-	E "github.com/yusing/go-proxy/error"
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type StreamPort struct {

internal/proxy/fields/stream_port_test.go

@@ -3,8 +3,8 @@ package fields
 import (
 	"testing"
 
-	E "github.com/yusing/go-proxy/error"
-	. "github.com/yusing/go-proxy/utils/testing"
+	E "github.com/yusing/go-proxy/internal/error"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 var validPorts = []string{

internal/proxy/fields/stream_scheme.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"strings"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 type StreamScheme struct {

internal/proxy/fields/timeout.go

@@ -3,7 +3,7 @@ package fields
 import (
 	"time"
 
-	E "github.com/yusing/go-proxy/error"
+	E "github.com/yusing/go-proxy/internal/error"
 )
 
 func ValidateDurationPostitive(value string) (time.Duration, E.NestedError) {

internal/proxy/provider/docker.go

@@ -7,11 +7,11 @@ import (
 	"strings"
 
 	"github.com/sirupsen/logrus"
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
-	R "github.com/yusing/go-proxy/route"
-	W "github.com/yusing/go-proxy/watcher"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
+	R "github.com/yusing/go-proxy/internal/route"
+	W "github.com/yusing/go-proxy/internal/watcher"
 )
 
 type DockerProvider struct {

internal/proxy/provider/docker_test.go

@@ -5,13 +5,13 @@ import (
 	"testing"
 
 	"github.com/docker/docker/api/types"
-	"github.com/yusing/go-proxy/common"
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	P "github.com/yusing/go-proxy/proxy"
-	T "github.com/yusing/go-proxy/proxy/fields"
+	"github.com/yusing/go-proxy/internal/common"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	P "github.com/yusing/go-proxy/internal/proxy"
+	T "github.com/yusing/go-proxy/internal/proxy/fields"
 
-	. "github.com/yusing/go-proxy/utils/testing"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 var dummyNames = []string{"/a"}

internal/proxy/provider/file.go

@@ -5,12 +5,12 @@ import (
 	"os"
 	"path"
 
-	"github.com/yusing/go-proxy/common"
-	E "github.com/yusing/go-proxy/error"
-	M "github.com/yusing/go-proxy/models"
-	R "github.com/yusing/go-proxy/route"
-	U "github.com/yusing/go-proxy/utils"
-	W "github.com/yusing/go-proxy/watcher"
+	"github.com/yusing/go-proxy/internal/common"
+	E "github.com/yusing/go-proxy/internal/error"
+	M "github.com/yusing/go-proxy/internal/models"
+	R "github.com/yusing/go-proxy/internal/route"
+	U "github.com/yusing/go-proxy/internal/utils"
+	W "github.com/yusing/go-proxy/internal/watcher"
 )
 
 type FileProvider struct {
@@ -94,5 +94,5 @@ func (p *FileProvider) LoadRoutesImpl() (routes R.Routes, res E.NestedError) {
 }
 
 func (p *FileProvider) NewWatcher() W.Watcher {
-	return W.NewFileWatcher(p.fileName)
+	return W.NewConfigFileWatcher(p.fileName)
 }

internal/proxy/provider/provider.go

@@ -5,9 +5,9 @@ import (
 	"path"
 
 	"github.com/sirupsen/logrus"
-	E "github.com/yusing/go-proxy/error"
-	R "github.com/yusing/go-proxy/route"
-	W "github.com/yusing/go-proxy/watcher"
+	E "github.com/yusing/go-proxy/internal/error"
+	R "github.com/yusing/go-proxy/internal/route"
+	W "github.com/yusing/go-proxy/internal/watcher"
 )
 
 type (

internal/route/http.go

@@ -1,7 +1,9 @@
 package route
 
 import (
+	"encoding/json"
 	"fmt"
+	"slices"
 	"sync"
 
 	"net/http"
@@ -9,14 +11,14 @@ import (
 	"strings"
 
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/common"
-	"github.com/yusing/go-proxy/docker/idlewatcher"
-	E "github.com/yusing/go-proxy/error"
-	. "github.com/yusing/go-proxy/http"
-	P "github.com/yusing/go-proxy/proxy"
-	PT "github.com/yusing/go-proxy/proxy/fields"
-	"github.com/yusing/go-proxy/route/middleware"
-	F "github.com/yusing/go-proxy/utils/functional"
+	"github.com/yusing/go-proxy/internal/common"
+	"github.com/yusing/go-proxy/internal/docker/idlewatcher"
+	E "github.com/yusing/go-proxy/internal/error"
+	. "github.com/yusing/go-proxy/internal/http"
+	P "github.com/yusing/go-proxy/internal/proxy"
+	PT "github.com/yusing/go-proxy/internal/proxy/fields"
+	"github.com/yusing/go-proxy/internal/route/middleware"
+	F "github.com/yusing/go-proxy/internal/utils/functional"
 )
 
 type (
@@ -170,10 +172,21 @@ func (u *URL) MarshalText() (text []byte, err error) {
 func ProxyHandler(w http.ResponseWriter, r *http.Request) {
 	mux, err := findMuxFunc(r.Host)
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusNotFound)
 		logrus.Error(E.Failure("request").
 			Subjectf("%s %s", r.Method, r.URL.String()).
 			With(err))
+		acceptTypes := r.Header.Values("Accept")
+		switch {
+		case slices.Contains(acceptTypes, "text/html"):
+
+		case slices.Contains(acceptTypes, "application/json"):
+			w.WriteHeader(http.StatusNotFound)
+			json.NewEncoder(w).Encode(map[string]string{
+				"error": err.Error(),
+			})
+		default:
+			http.Error(w, err.Error(), http.StatusNotFound)
+		}
 		return
 	}
 	mux.ServeHTTP(w, r)

internal/route/middleware/custom_error_page.go

@@ -0,0 +1,70 @@
+package middleware
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+	"github.com/yusing/go-proxy/internal/api/v1/error_page"
+	gpHTTP "github.com/yusing/go-proxy/internal/http"
+)
+
+const staticFilePathPrefix = "/$gperrorpage/"
+
+var CustomErrorPage = &Middleware{
+	before: func(next http.Handler, w ResponseWriter, r *Request) {
+		path := r.URL.Path
+		if path != "" && path[0] != '/' {
+			path = "/" + path
+		}
+		if strings.HasPrefix(path, staticFilePathPrefix) {
+			filename := path[len(staticFilePathPrefix):]
+			file, ok := error_page.GetStaticFile(filename)
+			if !ok {
+				http.NotFound(w, r)
+				errPageLogger.Errorf("unable to load resource %s", filename)
+			} else {
+				ext := filepath.Ext(filename)
+				switch ext {
+				case ".html":
+					w.Header().Set("Content-Type", "text/html; charset=utf-8")
+				case ".js":
+					w.Header().Set("Content-Type", "application/javascript; charset=utf-8")
+				case ".css":
+					w.Header().Set("Content-Type", "text/css; charset=utf-8")
+				default:
+					errPageLogger.Errorf("unexpected file type %q for %s", ext, filename)
+				}
+				w.Write(file)
+			}
+			return
+		}
+		next.ServeHTTP(w, r)
+	},
+	modifyResponse: func(resp *Response) error {
+		// only handles non-success status code and html/plain content type
+		contentType := gpHTTP.GetContentType(resp.Header)
+		if !gpHTTP.IsSuccess(resp.StatusCode) && (contentType.IsHTML() || contentType.IsPlainText()) {
+			errorPage, ok := error_page.GetErrorPageByStatus(resp.StatusCode)
+			if ok {
+				errPageLogger.Debugf("error page for status %d loaded", resp.StatusCode)
+				io.Copy(io.Discard, resp.Body) // drain the original body
+				resp.Body.Close()
+				resp.Body = io.NopCloser(bytes.NewReader(errorPage))
+				resp.ContentLength = int64(len(errorPage))
+				resp.Header.Set("Content-Length", fmt.Sprint(len(errorPage)))
+				resp.Header.Set("Content-Type", "text/html; charset=utf-8")
+			} else {
+				errPageLogger.Errorf("unable to load error page for status %d", resp.StatusCode)
+			}
+			return nil
+		}
+		return nil
+	},
+}
+
+var errPageLogger = logrus.WithField("middleware", "error_page")

internal/route/middleware/forward_auth.go

@@ -14,11 +14,11 @@ import (
 	"time"
 
 	"github.com/sirupsen/logrus"
-	"github.com/yusing/go-proxy/common"
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	gpHTTP "github.com/yusing/go-proxy/http"
-	U "github.com/yusing/go-proxy/utils"
+	"github.com/yusing/go-proxy/internal/common"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	gpHTTP "github.com/yusing/go-proxy/internal/http"
+	U "github.com/yusing/go-proxy/internal/utils"
 )
 
 type (
@@ -91,7 +91,7 @@ func newForwardAuth() (fa *forwardAuth) {
 }
 
 func (fa *forwardAuth) forward(next http.Handler, w ResponseWriter, req *Request) {
-	removeHop(req.Header)
+	gpHTTP.RemoveHop(req.Header)
 
 	faReq, err := http.NewRequestWithContext(
 		req.Context(),
@@ -105,10 +105,10 @@ func (fa *forwardAuth) forward(next http.Handler, w ResponseWriter, req *Request
 		return
 	}
 
-	copyHeader(faReq.Header, req.Header)
-	removeHop(faReq.Header)
+	gpHTTP.CopyHeader(faReq.Header, req.Header)
+	gpHTTP.RemoveHop(faReq.Header)
 
-	filterHeaders(faReq.Header, fa.AuthResponseHeaders)
+	gpHTTP.FilterHeaders(faReq.Header, fa.AuthResponseHeaders)
 	fa.setAuthHeaders(req, faReq)
 
 	faResp, err := fa.client.Do(faReq)
@@ -127,8 +127,8 @@ func (fa *forwardAuth) forward(next http.Handler, w ResponseWriter, req *Request
 	}
 
 	if faResp.StatusCode < http.StatusOK || faResp.StatusCode >= http.StatusMultipleChoices {
-		copyHeader(w.Header(), faResp.Header)
-		removeHop(w.Header())
+		gpHTTP.CopyHeader(w.Header(), faResp.Header)
+		gpHTTP.RemoveHop(w.Header())
 
 		redirectURL, err := faResp.Location()
 		if err != nil {

internal/route/middleware/middleware.go

@@ -3,9 +3,9 @@ package middleware
 import (
 	"net/http"
 
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	gpHTTP "github.com/yusing/go-proxy/http"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	gpHTTP "github.com/yusing/go-proxy/internal/http"
 )
 
 type (
@@ -21,7 +21,7 @@ type (
 
 	BeforeFunc         func(next http.Handler, w ResponseWriter, r *Request)
 	RewriteFunc        func(req *ProxyRequest)
-	ModifyResponseFunc func(res *Response) error
+	ModifyResponseFunc func(resp *Response) error
 	CloneWithOptFunc   func(opts OptionsRaw, rp *ReverseProxy) (*Middleware, E.NestedError)
 
 	OptionsRaw = map[string]any
@@ -68,7 +68,7 @@ func (m *Middleware) WithOptionsClone(optsRaw OptionsRaw, rp *ReverseProxy) (*Mi
 func PatchReverseProxy(rp *ReverseProxy, middlewares map[string]OptionsRaw) (res E.NestedError) {
 	befores := make([]BeforeFunc, 0, len(middlewares))
 	rewrites := make([]RewriteFunc, 0, len(middlewares))
-	modifyResponses := make([]ModifyResponseFunc, 0, len(middlewares))
+	modResps := make([]ModifyResponseFunc, 0, len(middlewares))
 
 	invalidM := E.NewBuilder("invalid middlewares")
 	invalidOpts := E.NewBuilder("invalid options")
@@ -96,7 +96,7 @@ func PatchReverseProxy(rp *ReverseProxy, middlewares map[string]OptionsRaw) (res
 			rewrites = append(rewrites, m.rewrite)
 		}
 		if m.modifyResponse != nil {
-			modifyResponses = append(modifyResponses, m.modifyResponse)
+			modResps = append(modResps, m.modifyResponse)
 		}
 	}
 
@@ -118,29 +118,26 @@ func PatchReverseProxy(rp *ReverseProxy, middlewares map[string]OptionsRaw) (res
 	}
 
 	if len(rewrites) > 0 {
-		origRewrite := rp.Rewrite
+		if rp.Rewrite != nil {
+			rewrites = append([]RewriteFunc{rp.Rewrite}, rewrites...)
+		}
 		rp.Rewrite = func(req *ProxyRequest) {
-			if origRewrite != nil {
-				origRewrite(req)
-			}
 			for _, rewrite := range rewrites {
 				rewrite(req)
 			}
 		}
 	}
 
-	if len(modifyResponses) > 0 {
-		origModifyResponse := rp.ModifyResponse
+	if len(modResps) > 0 {
+		if rp.ModifyResponse != nil {
+			modResps = append([]ModifyResponseFunc{rp.ModifyResponse}, modResps...)
+		}
 		rp.ModifyResponse = func(res *Response) error {
-			if origModifyResponse != nil {
-				return origModifyResponse(res)
+			b := E.NewBuilder("errors in middleware ModifyResponse")
+			for _, mr := range modResps {
+				b.AddE(mr(res))
 			}
-			for _, modifyResponse := range modifyResponses {
-				if err := modifyResponse(res); err != nil {
-					return err
-				}
-			}
-			return nil
+			return b.Build().Error()
 		}
 	}
 

internal/route/middleware/middlewares.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"strings"
 
-	D "github.com/yusing/go-proxy/docker"
+	D "github.com/yusing/go-proxy/internal/docker"
 )
 
 var middlewares map[string]*Middleware
@@ -14,15 +14,17 @@ func Get(name string) (middleware *Middleware, ok bool) {
 	return
 }
 
-// initialize middleware names
+// initialize middleware names and label parsers
 func init() {
 	middlewares = map[string]*Middleware{
-		"set_x_forwarded": SetXForwarded,
-		"add_x_forwarded": AddXForwarded,
-		"redirect_http":   RedirectHTTP,
-		"forward_auth":    ForwardAuth.m,
-		"modify_response": ModifyResponse.m,
-		"modify_request":  ModifyRequest.m,
+		"set_x_forwarded":   SetXForwarded,
+		"add_x_forwarded":   AddXForwarded,
+		"redirect_http":     RedirectHTTP,
+		"forward_auth":      ForwardAuth.m,
+		"modify_response":   ModifyResponse.m,
+		"modify_request":    ModifyRequest.m,
+		"error_page":        CustomErrorPage,
+		"custom_error_page": CustomErrorPage,
 	}
 	names := make(map[*Middleware][]string)
 	for name, m := range middlewares {

internal/route/middleware/modify_request.go

@@ -1,9 +1,9 @@
 package middleware
 
 import (
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	U "github.com/yusing/go-proxy/utils"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	U "github.com/yusing/go-proxy/internal/utils"
 )
 
 type (

internal/route/middleware/modify_request_test.go

@@ -4,7 +4,7 @@ import (
 	"slices"
 	"testing"
 
-	. "github.com/yusing/go-proxy/utils/testing"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestSetModifyRequest(t *testing.T) {

internal/route/middleware/modify_response.go

@@ -3,9 +3,9 @@ package middleware
 import (
 	"net/http"
 
-	D "github.com/yusing/go-proxy/docker"
-	E "github.com/yusing/go-proxy/error"
-	U "github.com/yusing/go-proxy/utils"
+	D "github.com/yusing/go-proxy/internal/docker"
+	E "github.com/yusing/go-proxy/internal/error"
+	U "github.com/yusing/go-proxy/internal/utils"
 )
 
 type (

internal/route/middleware/modify_response_test.go

@@ -4,7 +4,7 @@ import (
 	"slices"
 	"testing"
 
-	. "github.com/yusing/go-proxy/utils/testing"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestSetModifyResponse(t *testing.T) {

internal/route/middleware/redirect_http.go

@@ -3,7 +3,7 @@ package middleware
 import (
 	"net/http"
 
-	"github.com/yusing/go-proxy/common"
+	"github.com/yusing/go-proxy/internal/common"
 )
 
 var RedirectHTTP = &Middleware{

internal/route/middleware/redirect_http_test.go

@@ -4,8 +4,8 @@ import (
 	"net/http"
 	"testing"
 
-	"github.com/yusing/go-proxy/common"
-	. "github.com/yusing/go-proxy/utils/testing"
+	"github.com/yusing/go-proxy/internal/common"
+	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
 func TestRedirectToHTTPs(t *testing.T) {