Add Proxy to Sarama config

[padraicbc]

Description:
Set a Proxy URL that is picked up in Sarama to proxy Kafka connections over TCP.

Link to tracking Issue:
#21158
Testing:

Documentation:

[fatsheep9146]

Please add a changelog @padraicbc

[atoulme]

What happens if both env vars are set?

Can you include a line in README about this?

Is there a way to have a unit test to check this behavior?

[padraicbc]

I saw somewhere in the docs that any http(s)_proxy envs set would be picked up but not in the case of sarama it seem, that is why I went with this route.
It might be a better approach to have an env specific to sarama like SARAMA_PROXY as you are speaking Kafka, not http, so not a typical scenario. That or some optional arg you can set in the yaml. The latter is how I use it in a consumer I created, I have a WithProxy option which sets a proxy field on a struct. If set I do the above.

[padraicbc]

I am using something along these lines for my own purposes:

if p := os.Getenv("SARAMA_PROXY"); p != "" {

	log.Printf("using proxy: %s", p)
	httpProxyURI, err := url.Parse(p)
	if err != nil {
		return nil, err
	}

	httpDialer, err := proxy.FromURL(httpProxyURI, proxy.Direct)
	if err != nil {
		return nil, err
	}
	
	c.Net.Proxy = struct {
		Enable bool
		Dialer proxy.Dialer
	}{
		Enable: true,
		Dialer: httpDialer,
	}

}

Having an explicit env may be the cleanest way to go.

[MovieStoreGuy]

Please don't reference variables fetched from the operating environment, it complicates how to configure the exporter further and can't easily be caught in within the config validation to save time providing feedback to the user (if it is set incorrectly).

[fatsheep9146]

please fix the failed checks @padraicbc

[atoulme]

Your PR appears to be in a bad state. PTAL.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.

[padraicbc]

Hey @padraicbc ,

Do you need anymore help on this one?

Sorry, had a lot going on so this took a back seat. Can you repopen please as I am working on it now.

[pavolloffay]

@padraicbc do we need to have support directly in the config? How is this different to HTTP_PROXY env var supported by golang?

[padraicbc]

Sarama doesn't pick up envs and you won't be using a http proxy. We had squid running and tried numerous ways to make it play nice but you need to tunnel over a TCP proxy as we are talking Kafka, not HTTP.

[padraicbc]

I had used envs but it wasn't the preferred way. All this change does is alllow pointing to a TCP proxy you have registered. It is up to the end user to create and register it.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.

[padraicbc]

@MovieStoreGuy I was waiting on some feedback. Can I get this reopened and have someone take a look to see if we are on the same page please.