better build

.dockerignore

@@ -1 +1,3 @@
 Dockerfile
+tmp/**/*
+dist/*

Dockerfile

@@ -0,0 +1,25 @@
+from golang:1.21.4-alpine3.18 as build
+
+workdir /src
+copy go.mod go.sum .
+run go mod download
+
+copy . .
+run go test ./...
+run go build -o /go/bin/init -trimpath .
+
+# ------------------------------------------------------------------------
+from alpine:3.18.4
+
+workdir /layer
+run wget -O- https://dl-cdn.alpinelinux.org/alpine/v3.18/releases/x86_64/alpine-minirootfs-3.18.4-x86_64.tar.gz |tar zxv
+
+run apk add --no-cache -p . musl lvm2 lvm2-dmeventd udev cryptsetup e2fsprogs btrfs-progs lsblk
+run rm -rf usr/share/apk var/cache/apk
+
+copy --from=build /go/bin/init .
+
+# check viability
+run chroot /layer /init hello
+
+entrypoint ["sh","-c","find |cpio -H newc -o |base64"]

alpine/Dockerfile

@@ -1,12 +0,0 @@
-# ------------------------------------------------------------------------
-from alpine:3.15
-
-add alpine-minirootfs-3.15.0-x86_64.tar.gz /layer/
-
-workdir /layer
-
-run apk update
-run apk add -p . musl lvm2 lvm2-dmeventd udev cryptsetup e2fsprogs btrfs-progs
-run rm -rf usr/share/apk var/cache/apk
-
-entrypoint ["sh","-c","find |cpio -H newc -o |base64"]

main.go

@@ -50,6 +50,11 @@ func main() {
 }
 
 func runInit() {
+	if len(os.Args) > 1 && os.Args[1] == "hello" {
+		fmt.Println("hello world!")
+		os.Exit(0)
+	}
+
 	runtime.LockOSThread()
 
 	if pid := os.Getpid(); pid != 1 {