feat!: remove external dependencies

Remove the kingpin external dependency, and instead just use Go's stdlib
flag package.

BREAKING CHANGE: Long versions of command line flags are no longer supported.

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         run: make
       - name: Run and make request
         run: |
-          ./bin/casecmp --port=8080 &
+          ./bin/casecmp -p 8080 &
           curl --silent --retry 10 --retry-delay 1 --retry-connrefused \
               http://localhost:8080/
 

Makefile

@@ -4,11 +4,10 @@ VERSION ?= $(shell cat VERSION)
 SOURCES = $(shell find . -name '*.go' -o -name 'Makefile')
 
 $(BINARY): $(SOURCES)
-	CGO_ENABLED=0 go build -a -o ${BINARY} -ldflags \ "\
+	CGO_ENABLED=0 go build -o ${BINARY} -ldflags \ "\
 		-s -w \
 		-X main.version=${VERSION} \
-		-X main.commit=$(shell git show --format="%h" --no-patch) \
-		-X main.date=$(shell date +%Y-%m-%dT%T%z)"
+		-X main.commit=$(shell git show --format="%h" --no-patch)"
 
 .PHONY: build
 build: $(BINARY)

go.mod

@@ -1,11 +1,3 @@
 module github.com/jimeh/casecmp
 
 go 1.19
-
-require gopkg.in/alecthomas/kingpin.v2 v2.2.6
-
-require (
-	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
-	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 // indirect
-	github.com/stretchr/testify v1.7.0 // indirect
-)

go.sum

@@ -1,18 +0,0 @@
-github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafoB+tBA3gMyHYHrpOtNuDiK/uB5uXxq5wM=
-github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
-github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 h1:s6gZFSlWYmbqAuRjVTiNNhvNRfY2Wxp9nhfyel4rklc=
-github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
-gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -2,35 +2,35 @@ package main
 
 import (
 	"bytes"
+	"flag"
 	"fmt"
 	"log"
 	"net/http"
 	"os"
+	"strconv"
 	"strings"
 	"time"
-
-	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 var (
-	name        = "casecmp"
 	version = "dev"
 	commit  = "unknown"
-	date        = "unknown"
-	defaultPort = "8080"
+)
+
+const (
+	name        = "casecmp"
+	defaultPort = 8080
+	defaultBind = "0.0.0.0"
 )
 
 // Argument parsing setup.
 var (
-	portFlag = kingpin.Flag("port", "Port to listen to.").Short('p').
-			Default("").String()
-	bindFlag = kingpin.Flag("bind", "Bind address.").Short('b').
-			Default("0.0.0.0").String()
-	forceHTTPSFlag = kingpin.Flag(
-		"force-https", "Use https:// in example curl commands",
-	).Bool()
-	versionFlag = kingpin.Flag("version", "Print version info.").
-			Short('v').Bool()
+	portFlag       = flag.Int("p", defaultPort, "Port to listen on")
+	bindFlag       = flag.String("b", defaultBind, "Bind address")
+	forceHTTPSFlag = flag.Bool(
+		"f", false, "Use https:// in example curl commands",
+	)
+	versionFlag = flag.Bool("v", false, "Print version info")
 )
 
 func indexHandler(w http.ResponseWriter, r *http.Request) {
@@ -105,13 +105,16 @@ func printVersion() {
 	fmt.Println(buffer.String())
 }
 
-func startServer() {
-	if *portFlag == "" {
+func startServer() error {
+	if *portFlag == defaultPort {
 		envPort := os.Getenv("PORT")
 		if envPort != "" {
-			*portFlag = envPort
-		} else {
-			*portFlag = defaultPort
+			v, err := strconv.Atoi(envPort)
+			if err != nil {
+				return err
+			}
+
+			*portFlag = v
 		}
 	}
 
@@ -119,8 +122,9 @@ func startServer() {
 		*forceHTTPSFlag = true
 	}
 
-	address := *bindFlag + ":" + *portFlag
+	address := fmt.Sprintf("%s:%d", *bindFlag, *portFlag)
 	fmt.Printf("Listening on %s\n", address)
+
 	srv := &http.Server{
 		ReadTimeout:  5 * time.Second,
 		WriteTimeout: 5 * time.Second,
@@ -129,15 +133,19 @@ func startServer() {
 		Addr:         address,
 	}
 
-	log.Fatal(srv.ListenAndServe())
+	return srv.ListenAndServe()
 }
 
 func main() {
-	kingpin.Parse()
+	flag.Parse()
 
 	if *versionFlag {
 		printVersion()
-	} else {
-		startServer()
+		return
+	}
+
+	err := startServer()
+	if err != nil {
+		log.Fatal(err)
 	}
 }