♻️ refactor: Simplify Dockerfile and Makefile, improve CLI

Refactored Dockerfile for clarity and efficiency, using multi-stage builds and Alpine base image. Updated Makefile for streamlined commands. Improved CLI by deferring `Gosched` and simplifying proxy header handling.

Author: tarampampam

.devcontainer/devcontainer.json

@@ -1,61 +1,36 @@
 # syntax=docker/dockerfile:1
 
-# -✂- this stage is used to develop and build the application locally -------------------------------------------------
-FROM docker.io/library/golang:1.24-bookworm AS develop
-
-# use the /var/tmp/go as the GOPATH to reuse the modules cache
-ENV GOPATH="/var/tmp/go"
-
-RUN set -x \
-    # renovate: source=github-releases name=golangci/golangci-lint
-    && GOLANGCI_LINT_VERSION="2.3.0" \
-    && wget -O- -nv "https://cdn.jsdelivr.net/gh/golangci/golangci-lint@v${GOLANGCI_LINT_VERSION}/install.sh" \
-      | sh -s -- -b /bin "v${GOLANGCI_LINT_VERSION}"
-
-RUN set -x \
-    # customize the shell prompt (for the bash)
-    && echo "PS1='\[\033[1;36m\][go] \[\033[1;34m\]\w\[\033[0;35m\] \[\033[1;36m\]# \[\033[0m\]'" >> /etc/bash.bashrc
-
-WORKDIR /src
-
-# burn the modules cache
-RUN \
-    --mount=type=bind,source=go.mod,target=/src/go.mod \
-    --mount=type=bind,source=go.sum,target=/src/go.sum \
-    go mod download -x \
-    && find "${GOPATH}" -type d -exec chmod 0777 {} \; \
-    && find "${GOPATH}" -type f -exec chmod 0666 {} \;
-
 # -✂- this stage is used to compile the application -------------------------------------------------------------------
-FROM develop AS compile
+FROM docker.io/library/golang:1.24-alpine AS compile
 
 # can be passed with any prefix (like `v1.2.3@GITHASH`), e.g.: `docker build --build-arg "APP_VERSION=v1.2.3" .`
 ARG APP_VERSION="undefined@docker"
 
 # copy the source code
 COPY . /src
 
+WORKDIR /src
+
 RUN set -x \
-    && go generate ./... \
-    && CGO_ENABLED=0 LDFLAGS="-s -w -X gh.tarampamp.am/error-pages/internal/appmeta.version=${APP_VERSION}" \
-      go build -trimpath -ldflags "${LDFLAGS}" -o /tmp/error-pages ./cmd/error-pages/ \
+    && go generate -skip readme ./... \
+    && CGO_ENABLED=0 go build \
+      -trimpath \
+      -ldflags "-s -w -X gh.tarampamp.am/error-pages/internal/appmeta.version=${APP_VERSION}" \
+      -o /tmp/error-pages \
+      ./cmd/error-pages/ \
     && /tmp/error-pages --version \
     && /tmp/error-pages -h
 
-# -✂- this stage is used to prepare the runtime fs --------------------------------------------------------------------
-FROM docker.io/library/alpine:3.22 AS rootfs
-
 WORKDIR /tmp/rootfs
 
 # prepare rootfs for runtime
 RUN set -x \
     && mkdir -p ./etc/ssl/certs ./bin \
     && echo 'appuser:x:10001:10001::/nonexistent:/sbin/nologin' > ./etc/passwd \
     && echo 'appuser:x:10001:' > ./etc/group \
-    && cp /etc/ssl/certs/ca-certificates.crt ./etc/ssl/certs/
-
-# take the binary from the compile stage
-COPY --from=compile /tmp/error-pages ./bin/error-pages
+    && cp /etc/ssl/certs/ca-certificates.crt ./etc/ssl/certs/ \
+    && mv /tmp/error-pages ./bin/error-pages \
+    && chmod 755 ./bin/error-pages
 
 WORKDIR /tmp/rootfs/opt
 
@@ -81,7 +56,7 @@ LABEL \
     org.opencontainers.image.licenses="MIT"
 
 # import from builder
-COPY --from=rootfs /tmp/rootfs /
+COPY --from=compile /tmp/rootfs /
 
 # use an unprivileged user
 USER 10001:10001
@@ -95,7 +70,7 @@ ENV LOG_LEVEL="warn" \
     LOG_FORMAT="json"
 
 # docs: https://docs.docker.com/reference/dockerfile/#healthcheck
-HEALTHCHECK --interval=10s --start-interval=1s --start-period=5s --timeout=2s CMD ["/bin/error-pages", "healthcheck"]
+HEALTHCHECK --interval=10s --start-interval=1s --start-period=2s --timeout=1s CMD ["/bin/error-pages", "healthcheck"]
 
 ENTRYPOINT ["/bin/error-pages"]
 

Dockerfile

@@ -1,38 +1,18 @@
 #!/usr/bin/make
 
-DC_RUN_ARGS = --rm --user "$(shell id -u):$(shell id -g)"
+.DEFAULT_GOAL : build
 
-.DEFAULT_GOAL : help
-
-help: ## Show this help
-	@printf "\033[33m%s:\033[0m\n" 'Available commands'
-	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {printf "  \033[32m%-11s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)
-
-.PHONY: up
-up: ## Start the application in watch mode
-	docker compose kill web --remove-orphans 2>/dev/null || true
-	docker compose up --detach --wait web
-	$$SHELL -c "\
-		trap 'docker compose down --remove-orphans --timeout 30' EXIT; \
-		docker compose watch --no-up web \
-	"
-
-.PHONY: down
-down: ## Stop the application
-	docker compose down --remove-orphans
+gen: ## Generate code
+	go generate ./...
 
-.PHONY: shell
-shell: ## Start shell into development environment
-	docker compose run -ti $(DC_RUN_ARGS) develop bash
+build: gen ## Build the application
+	CGO_ENABLED=0 go build -trimpath -ldflags "-s -w" -o ./error-pages ./cmd/error-pages/
 
-.PHONY: test
 test: ## Run tests
-	docker compose run $(DC_RUN_ARGS) develop gotestsum --format pkgname -- -race -timeout 2m ./...
+	go test -race ./...
 
-.PHONY: lint
-lint: ## Run linters
-	docker compose run $(DC_RUN_ARGS) develop golangci-lint run
+lint: ## Run linters (requires https://github.com/golangci/golangci-lint installed)
+	golangci-lint run
 
-.PHONY: gen
-gen: ## Generate code
-	docker compose run $(DC_RUN_ARGS) develop go generate ./...
+up: build ## Start the application at http://localhost:8080
+	./error-pages --log-level debug serve --show-details --proxy-headers=X-Foo,Bar,Baz_blah

Makefile

@@ -6,18 +6,19 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"runtime"
 	"syscall"
 
 	"go.uber.org/automaxprocs/maxprocs"
 
 	"gh.tarampamp.am/error-pages/internal/cli"
 )
 
+// set GOMAXPROCS to match Linux container CPU quota.
+var _, _ = maxprocs.Set(maxprocs.Min(1), maxprocs.Logger(func(string, ...any) {}))
+
 // main CLI application entrypoint.
 func main() {
-	// automatically set GOMAXPROCS to match Linux container CPU quota
-	_, _ = maxprocs.Set(maxprocs.Min(1), maxprocs.Logger(func(_ string, _ ...any) {}))
-
 	if err := run(); err != nil {
 		_, _ = fmt.Fprintln(os.Stderr, err.Error())
 
@@ -27,9 +28,11 @@ func main() {
 
 // run this CLI application.
 func run() error {
+	defer runtime.Gosched() // increase the chance of running deferred functions before exiting
+
 	// create a context that is canceled when the user interrupts the program
 	var ctx, cancel = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer cancel()
 
-	return (cli.NewApp(filepath.Base(os.Args[0]))).Run(ctx, os.Args)
+	return cli.NewApp(filepath.Base(os.Args[0])).Run(ctx, os.Args)
 }

cmd/error-pages/main.go

@@ -16,7 +16,7 @@ import (
 	"gh.tarampamp.am/error-pages/internal/logger"
 )
 
-//go:generate go run app_generate.go
+//go:generate go run update_readme.go
 
 // NewApp creates a new console application.
 func NewApp(appName string) *cli.Command {

compose.yml

@@ -220,7 +220,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 					m[http.CanonicalHeaderKey(strings.TrimSpace(header))] = struct{}{}
 				}
 
-				clear(cfg.ProxyHeaders) // clear the list before adding new headers
+				cfg.ProxyHeaders = make([]string, 0, len(m)) // clear the list before adding new headers
 
 				for header := range m {
 					cfg.ProxyHeaders = append(cfg.ProxyHeaders, header)