Add webserver dockerfile

.gitignore

@@ -0,0 +1 @@
+webserver/webserver

README.md

@@ -7,3 +7,8 @@ The containers are stored on my gitea instance, so you can pull them like this:
 ```bash
 docker pull gitea.elara.ws/elara6331/golang:latest
 ```
+
+### Images
+
+- `golang`: An alpine-based image with Go installed
+- `webserver`: A very simple webserver

webserver/Dockerfile

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+FROM busybox:latest
+COPY webserver /usr/bin/webserver
+RUN mkdir /html
+ENTRYPOINT webserver

webserver/build.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+if [[ $# == 0 ]]; then
+	echo "Usage: $0 <arch>"
+	exit 1
+fi
+
+GOOS=linux GOARCH=$1 go build -o webserver ./cmd/main.go
+
+docker login gitea.elara.ws
+docker build . -t "gitea.elara.ws/elara6331/webserver:$1"
+docker push "gitea.elara.ws/elara6331/webserver:$1"

webserver/cmd/main.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+)
+
+func main() {
+	addr := os.Getenv("WEBSERVER_ADDR")
+	if addr == "" {
+		addr = ":8000"
+	}
+	log.Println("Starting HTTP server at", addr)
+
+	h := http.FileServer(http.Dir("/html"))
+	h = methodMiddleware(h)
+	h = logMiddleware(h)
+	http.ListenAndServe(addr, h)
+}
+
+func methodMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			io.WriteString(w, "Method not allowed: "+r.Method)
+		} else {
+			next.ServeHTTP(w, r)
+		}
+	})
+}
+
+func logMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		next.ServeHTTP(w, r)
+		log.Printf("[http] Request from %s; latency=%s, method=%s, path=%q\n", getRealIP(r), time.Since(start), r.Method, r.URL.Path)
+	})
+}
+
+func getRealIP(r *http.Request) string {
+	xff := r.Header.Get("X-Forwarded-For")
+	if xff != "" {
+		before, _, ok := strings.Cut(xff, ", ")
+		if ok {
+			return before
+		} else {
+			return xff
+		}
+	}
+
+	xrip := r.Header.Get("X-Real-IP")
+	if xrip != "" {
+		return xrip
+	}
+
+	return r.RemoteAddr
+}

webserver/manifest.sh

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+#!/bin/bash
+
+tag="$1"
+tag="${tag:=latest}"
+
+docker login gitea.elara.ws
+docker manifest create "gitea.elara.ws/elara6331/webserver:$tag" \
+	--amend gitea.elara.ws/elara6331/webserver:amd64 \
+	--amend gitea.elara.ws/elara6331/webserver:arm64 \
+	--amend gitea.elara.ws/elara6331/webserver:riscv64
+docker manifest push "gitea.elara.ws/elara6331/webserver:$tag"