Directly build restic binary in release Docker container

.dockerignore

@@ -4,7 +4,6 @@
 changelog/
 doc/
 docker/
-helpers/
 
 # Files
 .gitignore

docker/Dockerfile.release

@@ -1,20 +1,18 @@
-FROM --platform=$BUILDPLATFORM alpine:latest as helper
+# the official binaries are cross-built from Linux running on an AMD64 host
+# other architectures also seem to generate identical binaries but stay on the safe side
+FROM --platform=linux/amd64 restic/builder:latest as helper
 
-ARG VERSION
 ARG TARGETOS
 ARG TARGETARCH
 
-# add release binary for the appropriate platform
-COPY restic_${VERSION}_${TARGETOS}_${TARGETARCH}.bz2 /
-RUN apk add --update --no-cache bzip2
-RUN set -e && \
-        bzcat restic_${VERSION}_${TARGETOS}_${TARGETARCH}.bz2 > restic && \
-        chmod +x restic
+COPY . /restic
+RUN go run helpers/build-release-binaries/main.go --platform $TARGETOS/$TARGETARCH --skip-compress
+RUN mv /output/restic_${TARGETOS}_${TARGETARCH} /output/restic
 
 
 FROM alpine:latest
 
-COPY --from=helper /restic /usr/bin
+COPY --from=helper /output/restic /usr/bin
 RUN apk add --update --no-cache ca-certificates fuse openssh-client tzdata jq
 
 ENTRYPOINT ["/usr/bin/restic"]

helpers/build-release-binaries/main.go

@@ -22,6 +22,8 @@ var opts = struct {
 	OutputDir      string
 	Tags           string
 	PlatformSubset string
+	Platform       string
+	SkipCompress   bool
 	Version        string
 }{}
 
@@ -31,6 +33,8 @@ func init() {
 	pflag.StringVarP(&opts.OutputDir, "output", "o", "/output", "path to the output `directory`")
 	pflag.StringVar(&opts.Tags, "tags", "", "additional build `tags`")
 	pflag.StringVar(&opts.PlatformSubset, "platform-subset", "", "specify `n/t` to only build this subset")
+	pflag.StringVarP(&opts.Platform, "platform", "p", "", "specify `os/arch` to only build this specific platform")
+	pflag.BoolVar(&opts.SkipCompress, "skip-compress", false, "skip binary compression step")
 	pflag.StringVar(&opts.Version, "version", "", "use `x.y.z` as the version for output files")
 	pflag.Parse()
 }
@@ -188,7 +192,9 @@ func buildForTarget(sourceDir, outputDir, goos, goarch string) (filename string)
 	filename = build(sourceDir, outputDir, goos, goarch)
 	touch(filepath.Join(outputDir, filename), mtime)
 	chmod(filepath.Join(outputDir, filename), 0755)
-	filename = compress(goos, outputDir, filename)
+	if !opts.SkipCompress {
+		filename = compress(goos, outputDir, filename)
+	}
 	return filename
 }
 
@@ -311,6 +317,8 @@ func main() {
 		if err != nil {
 			die("%s", err)
 		}
+	} else if opts.Platform != "" {
+		targets = buildPlatformList([]string{opts.Platform})
 	}
 
 	sourceDir := abs(opts.SourceDir)

helpers/prepare-release/main.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
+	"math/rand"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -409,19 +410,19 @@ func signFiles(filenames ...string) {
 	}
 }
 
-func updateDocker(outputDir, version string) string {
-	run("docker", "buildx", "create", "--name", "restic-release-builder", "--driver", "docker-container", "--bootstrap")
+func updateDocker(sourceDir, version string) string {
+	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	builderName := fmt.Sprintf("restic-release-builder-%d", r.Int())
+	run("docker", "buildx", "create", "--name", builderName, "--driver", "docker-container", "--bootstrap")
 
-	cmds := ""
+	buildCmd := fmt.Sprintf("docker buildx build --builder %s --platform linux/386,linux/amd64,linux/arm,linux/arm64 --pull -f docker/Dockerfile.release %q", builderName, sourceDir)
+	run("sh", "-c", buildCmd+" --no-cache")
 
+	publishCmds := ""
 	for _, tag := range []string{"restic/restic:latest", "restic/restic:" + version} {
-		cmd := fmt.Sprintf("docker buildx build --builder restic-release-builder --platform linux/386,linux/amd64,linux/arm,linux/arm64 --pull --tag %q -f docker/Dockerfile.release --build-arg VERSION=%q %q", tag, version, outputDir)
-		run("sh", "-c", cmd)
-
-		cmds += cmd + " --push\n"
+		publishCmds += buildCmd + fmt.Sprintf(" --tag %q --push\n", tag)
 	}
-
-	return cmds + "\ndocker buildx rm restic-release-builder"
+	return publishCmds + "\ndocker buildx rm " + builderName
 }
 
 func tempdir(prefix string) string {
@@ -470,15 +471,14 @@ func main() {
 
 	extractTar(tarFilename, sourceDir)
 	runBuild(sourceDir, opts.OutputDir, opts.Version)
-	rmdir(sourceDir)
 
 	sha256sums(opts.OutputDir, filepath.Join(opts.OutputDir, "SHA256SUMS"))
 
 	signFiles(filepath.Join(opts.OutputDir, "SHA256SUMS"), tarFilename)
 
-	dockerCmds := updateDocker(opts.OutputDir, opts.Version)
+	dockerCmds := updateDocker(sourceDir, opts.Version)
 
 	msg("done, output dir is %v", opts.OutputDir)
 
-	msg("now run:\n\ngit push --tags origin master\n%s\n", dockerCmds)
+	msg("now run:\n\ngit push --tags origin master\n%s\n\nrm -rf %q", dockerCmds, sourceDir)
 }