Rewrite `stunnerctl` in Go

[rg0now]

This issue tracks the progress on rewriting stunnerctl in Go.

stunnerctl is a small CLI utility that simplifies the interaction with STUNner. Currently it offers a single command, stunnerctl running-config, which allows to dump a gateway hierarchy in a human readable form. In the long run, stunnerctl will obtain further features, like

• stunnerctl version/status to get current cluster-wide STUNner version and status,
• stunnerctl config as a fancier form of the current running-config functionality,
• stunnerctl install to install STUNner via the CLI,
• stunnerctl monitor/dashboard for monitoring, and
• stunnerctl connect to control multicluster STUNner (once we implement it).

In addition, stunnerctl will need to provide the standard kubectl goodies, like support for taking Kubernetes config from KUBECONFIG, --kubeconfig, or --context.

Currently stunnerctl is a Bash script that talks to Kubernetes via kubectl and parses JSON responses using jq. Understandably, this is not really future-proof.

The goal is to rewrite stunnerctl in Go using the standard Go CLI tooling (viper, cobra, etc.).

[bananu7]

As a user, stunnerctl works perfectly fine for me. turncat, OTOH, being written in Go, is a source of problems.

[levaitamas]

hi @bananu7,

Great, happy to hear that stunnerctl works well!
I am wondering whether releasing binaries for turncat would help. What do you think?

[bananu7]

@levaitamas You're actually releasing the binaries, just not advertising it :) https://hub.docker.com/r/l7mp/turncat

I was quite angry at it not working yesterday (as you can imagine), but being real for a second:

• it didn't compile on Windows because of platform specific API (I assume?)

.\uri.go:149:29: cannot use int(descriptor) (value of type int) as syscall.Handle value in argument to syscall.SetsockoptInt

• it didn't compile on Ubuntu because of...

non-pc-relative relocation address for go:info.int is too big

I'd happily build it but after two tries I kind of lost my patience. I think for most of Stunner's userbase the dockerized release is fine, if it's maintained and in the readme.

[levaitamas]

Hi @bananu7,

Wow, nice catch! 💯 We also have a net-debug image that has turncat built-in: https://hub.docker.com/r/l7mp/net-debug

Sorry about the build failures, and thank you for your feedback! TBH, we never tried to compile turncat on Windows.
On Ubuntu/Alpine this should work on amd64 and arm64 machines (taken from the net-debug Dockerfile):

CGO_ENABLED=0 GOOS=linux go build -ldflags="-w -s" -trimpath -o turncat cmd/turncat/main.go

I think for most of Stunner's userbase the dockerized release is fine, if it's maintained and in the readme.

That's a good point. We will definitely mention it in the docs. Thanks!

[rg0now]

As per the Windows compilation problem, I think it is indeed a platform issue. This is quite puzzling given that we deliberately use the syscall package that is supposed to be portable across OSes, instead of golang.org/x/sys/unix that contains the UNIX specific stuff. Maybe we could steal some ideas from go-reuse to make turncat really portable? Anyone care to submit a PR?