Support Consul Connect Envoy Command on Windows

[absolutelightning]

Description

Add support for consul connect envoy command on windows. This PR fixes the comments of PR - #15114

Testing

• Built consul.exe from this branch on windows and hosted here - AWS S3
• Updated the tutorial and changed the consul_url.default value to AWS S3
• Followed the steps in the tutorial and verified that everything is working as described.

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

[dhiaayachi]

Thank you for working on this @absolutelightning

I left few comments/suggestions. The only really blocker is the choice of mmap library.

[dhiaayachi]

If my understanding is right, this uses mmap to keep the file in memory and not write it to disk to match the behaviour of named pipe in the unix version

Maybe we can use something like this library to continue using named pipes even in windows and have an equivalent implementation on all OSes?

[absolutelightning]

please help me understand we need to use both libraries npipe and mmap or any one?

[dhiaayachi]

I think npipe is the best choice as we would like to keep both implementation similar between windows and nix, but if that's not possible we can use mmap.

[absolutelightning]

This library creates a connection from which we can read lines or can create server. I am not able to understand how we can use it here. Can you please help @dhiaayachi ?

[dhiaayachi]

	conn, err := npipe.Dial(`\\.\pipe\mypipe`)
	if err != nil {
		// handle error
	}
	if _, err := fmt.Fprintln(conn, "Hi server!"); err != nil {
		// handle error
	}
	r := bufio.NewReader(conn)
	msg, err := r.ReadString('\n')
	if err != nil {
		// handle eror
	}
	fmt.Println(msg)

Here is an example from the library. You can use it similarly to what we have in the nix implementation.

[absolutelightning]

@dhiaayachi comments addressed. please review.

[dhiaayachi]

I left few other questions, I'm not sure I understand some of the comments about not being able to clean up.

[dhiaayachi]

I'm not sure I understand the reasoning behind that, why don't we wait for it to be done and is this specific to Windows?

[absolutelightning]

Not specific to Windows. https://github.com/hashicorp/consul/blob/b0a2e33e0a6c4ec411266dfcef38a3a648fefb50/command/connect/envoy/exec_unix.go#L127C1-L129C10

[dhiaayachi]

I'm not sure I understand the reasoning here, why don't we defer the clean up to after the envoy process finish?

[absolutelightning]

This logic is not specific to windows. Please see - unix version - https://github.com/hashicorp/consul/blob/b0a2e33e0a6c4ec411266dfcef38a3a648fefb50/command/connect/envoy/exec_unix.go#L127C1-L129C10

[dhiaayachi]

Thank you for the explanation @absolutelightning 😃

LGTM!

[absolutelightning]

Thank you for the explanation @absolutelightning 😃

LGTM!

Thanks.