Question: How to debug buildah bud with "unshare.MaybeReexecUsingUserNamespace(false)" ?

[cmoulliard]

Question

Is there a way to avoid that when we remote debug using dlv, the following line of code, which launches under the hood a sub-command will cause an exit of the debugger ?

func main() {
	if _, ok := os.LookupEnv("DEBUG"); ok && (len(os.Args) <= 1 || os.Args[1] != "from-debugger") {
		args := []string {
			"--listen=:2345",
			"--headless=true",
			"--api-version=2",
			"--accept-multiclient",
			"exec",
			"/buildah-app", "from-debugger",
		}
		err := syscall.Exec("/usr/local/bin/dlv", append([]string{"/usr/local/bin/dlv"}, args...), os.Environ())
		if err != nil {
			fmt.Fprintf(os.Stderr, "error: %v\n", err)
			os.Exit(1)
		}
	}

	ctx := context.TODO()

	if buildah.InitReexec() {
		return
	}

	// TODO: Check how we could continue to use the debugger as the following code exec a sub-command and by consequence it exits
	unshare.MaybeReexecUsingUserNamespace(false)

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[rhatdan]

Any ideas on this @giuseppe ?

[giuseppe]

It is better to start the debugging session from a buildah unshare session so buildah won't need to re-exec itself

[cmoulliard]

debugging session from a buildah unshare session

Can you elaborate please as this is not clear for me when we use go programming + dlv how we could achieve that ? @giuseppe

[giuseppe]

please run buildah unshare. It will run a new shell, and from that environment you can use dlv in the same way as you'd do as root on the host, since buildah won't re-exec again, so you can easily attach to the same process that will run the build

[cmoulliard]

please run buildah unshare

Macos users cannot natively use buildah on their machine. So, that won't work. @giuseppe

[giuseppe]

How on MacOS do you even hit the issue of buildah re-execing itself?

[cmoulliard]

When I debug the go lang application - https://github.com/redhat-buildpacks/poc/blob/9a9687ba2f89b8e39e0747c7e8cd41980b4f8255/buildah/code/main.go#L129