build: provide a flag to disable publishing in dockerx build (#31098)

This changes the `-upload` flag to just toggle the upload. The remote
image name is now configured using the `-hub` flag.

.travis.yml

@@ -25,7 +25,7 @@ jobs:
       before_install:
         - export DOCKER_CLI_EXPERIMENTAL=enabled
       script:
-        - go run build/ci.go dockerx -platform "linux/amd64,linux/arm64,linux/riscv64" -upload ethereum/client-go
+        - go run build/ci.go dockerx -platform "linux/amd64,linux/arm64,linux/riscv64" -hub ethereum/client-go -upload
 
     # This builder does the Linux Azure uploads
     - stage: build

build/ci.go

@@ -684,7 +684,8 @@ func maybeSkipArchive(env build.Environment) {
 func doDockerBuildx(cmdline []string) {
 	var (
 		platform = flag.String("platform", "", `Push a multi-arch docker image for the specified architectures (usually "linux/amd64,linux/arm64")`)
-		upload   = flag.String("upload", "", `Where to upload the docker image (usually "ethereum/client-go")`)
+		hubImage = flag.String("hub", "ethereum/client-go", `Where to upload the docker image`)
+		upload   = flag.Bool("upload", false, `Whether to trigger upload`)
 	)
 	flag.CommandLine.Parse(cmdline)
 
@@ -719,25 +720,33 @@ func doDockerBuildx(cmdline []string) {
 		tags = []string{"stable", fmt.Sprintf("release-%v", version.Family), "v" + version.Semantic}
 	}
 	// Need to create a mult-arch builder
+	check := exec.Command("docker", "buildx", "inspect", "multi-arch-builder")
+	if check.Run() != nil {
 		build.MustRunCommand("docker", "buildx", "create", "--use", "--name", "multi-arch-builder", "--platform", *platform)
+	}
 
 	for _, spec := range []struct {
 		file string
 		base string
 	}{
-		{file: "Dockerfile", base: fmt.Sprintf("%s:", *upload)},
-		{file: "Dockerfile.alltools", base: fmt.Sprintf("%s:alltools-", *upload)},
+		{file: "Dockerfile", base: fmt.Sprintf("%s:", *hubImage)},
+		{file: "Dockerfile.alltools", base: fmt.Sprintf("%s:alltools-", *hubImage)},
 	} {
 		for _, tag := range tags { // latest, stable etc
 			gethImage := fmt.Sprintf("%s%s", spec.base, tag)
-			build.MustRunCommand("docker", "buildx", "build",
+			cmd := exec.Command("docker", "buildx", "build",
 				"--build-arg", "COMMIT="+env.Commit,
 				"--build-arg", "VERSION="+version.WithMeta,
 				"--build-arg", "BUILDNUM="+env.Buildnum,
 				"--tag", gethImage,
 				"--platform", *platform,
-				"--push",
-				"--file", spec.file, ".")
+				"--file", spec.file,
+			)
+			if *upload {
+				cmd.Args = append(cmd.Args, "--push")
+			}
+			cmd.Args = append(cmd.Args, ".")
+			build.MustRun(cmd)
 		}
 	}
 }