initial release

.github/workflows/release.yml

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+name: Docker Image CI
+
+on:
+  release:
+    types: [created]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Save version
+      run: basename $GITHUB_REF >version.txt
+
+    - name: Docker meta
+      id: meta
+      uses: docker/metadata-action@v4
+      with:
+        images: |
+          lindex/melp
+        tags: |
+          type=semver,pattern=v{{version}}
+          type=semver,pattern=v{{major}}.{{minor}}
+        labels: |
+          org.opencontainers.image.title=melp
+          org.opencontainers.image.description=Simple service to test TCP-connections
+          org.opencontainers.image.source=https://github.com/AB-Lindex/tcpecho
+          org.opencontainers.image.url=https://github.com/AB-Lindex/tcpecho
+          org.opencontainers.image.licenses=apache2.0
+
+    - name: Login to DockerHub
+      uses: docker/login-action@v2
+      with:
+        username: ${{ secrets.DOCKERHUB_USER }}
+        password: ${{ secrets.DOCKERHUB_SECRET }}
+
+    - name: Build and push Docker images
+      uses: docker/build-push-action@v3
+      with:
+        context: .
+        push: true
+        tags: ${{ steps.meta.outputs.tags }}

.gitignore

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+version.txt

Dockerfile

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+# syntax=docker/dockerfile:1
+
+##
+## STEP 1 - BUILD
+##
+
+# specify the base image to  be used for the application, alpine or ubuntu
+FROM golang:1.21-alpine AS build
+
+# create a working directory inside the image
+WORKDIR /app
+
+# copy Go modules and dependencies to image
+COPY *go* version.txt ./
+
+# compile application (static linked)
+RUN CGO_ENABLED=0 go build -ldflags="-extldflags=-static" -o /tcpecho
+
+##
+## STEP 2 - DEPLOY
+##
+FROM scratch
+
+ENV PATH=/
+
+WORKDIR /
+
+COPY --from=build /tcpecho /
+
+CMD ["/tcpecho"]

Makefile

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+SOURCES=*.go
+
+build: bin/tcpecho
+
+bin/tcpecho: $(SOURCES) Makefile go.mod
+	@mkdir -p bin
+	go build -o bin/tcpecho .
+
+run: bin/tcpecho
+	bin/tcpecho
+
+runc:
+	docker run --rm -it tcpecho:docker
+
+docker:
+	-docker rmi tcpecho:docker
+	docker build -t tcpecho:docker .
+
+nerdctl:
+	-docker rmi tcpecho:nerdctl
+	nerdctl build -t tcpecho:nerdctl .
+
+check:
+	@echo "Checking...\n"
+	gocyclo -over 15 . || echo -n ""
+	@echo ""
+	golint -min_confidence 0.21 -set_exit_status ./...
+	@echo ""
+	go mod verify
+	@echo "\nAll ok!"
+
+check2:
+	@echo ""
+	golangci-lint run -E misspell -E depguard -E dupl -E goconst -E gocyclo -E ifshort -E predeclared -E tagliatelle -E errorlint -E godox -D structcheck
+
+release:
+	gh release create `cat version.txt`

go.mod

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+module github.com/AB-Lindex/tcpecho
+
+go 1.21.4

main.go

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+package main
+
+import (
+	"bufio"
+	_ "embed"
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+//go:embed version.txt
+var version string
+
+var (
+	port     int = 43210
+	workerID int
+	hostname string
+)
+
+func main() {
+	if len(os.Args) > 1 {
+		v, err := strconv.Atoi(os.Args[1])
+		if err != nil {
+			log.Fatal(err)
+		}
+		port = v
+	}
+
+	hostname, _ = os.Hostname()
+	l, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("%s Listening on port %d...", version, port)
+	defer l.Close()
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			log.Fatal(err)
+		}
+		workerID++
+		go handle(conn, workerID)
+	}
+}
+
+func handle(c net.Conn, id int) {
+	log.Printf("%d: starting connection with %v", id, c.RemoteAddr().String())
+	defer func() {
+		log.Printf("%d: closing connection with %v", id, c.RemoteAddr().String())
+		c.Close()
+	}()
+	fmt.Fprintf(c, "Welcome to tcpecho on %s:%d\nThis is handler #%d, type '.' to quit\n", hostname, port, id)
+	rd := bufio.NewScanner(c)
+	for {
+		if rd.Scan() {
+			txt := rd.Text()
+			if txt == "." {
+				fmt.Fprintln(c, "Goodbye.")
+				return
+			}
+			do(id, c, txt)
+		}
+	}
+}
+
+type dooer func(id int, c net.Conn, cmd, args string)
+
+var commands = map[string]dooer{
+	"date": dateCmd,
+	"time": timeCmd,
+	"info": infoCmd,
+}
+
+func do(id int, c net.Conn, txt string) {
+	parts := strings.SplitN(txt, " ", 2)
+	var args string
+	if len(parts) > 1 {
+		args = strings.TrimSpace(parts[1])
+	}
+	for cmd, fn := range commands {
+		if strings.EqualFold(cmd, parts[0]) {
+			log.Printf("%d: doing '%s'", id, cmd)
+			fn(id, c, cmd, args)
+			return
+		}
+	}
+	fmt.Fprintf(c, "unknown command: '%s'\n", parts[0])
+}
+
+func dateCmd(id int, c net.Conn, cmd, args string) {
+	fmt.Fprintf(c, "The date is %s\n", time.Now().Format(time.DateOnly))
+}
+
+func timeCmd(id int, c net.Conn, cmd, args string) {
+	fmt.Fprintf(c, "The time is %s\n", time.Now().Format(time.TimeOnly))
+}
+
+func infoCmd(id int, c net.Conn, cmd, args string) {
+	fmt.Fprintf(c, "You are connecting from %s\n", c.RemoteAddr().String())
+}