fix(outputs.influxdb*): Support setting Host header

[slai]

Summary

The outputs.influxdb and outputs.influxdb_v2 plugins currently do not support setting the Host header in the http_headers config parameter. If set, it is silently dropped by Go's HTTP client.

The Go HTTP client requires the Host header to be set on the http.Request struct instead. This is already done in other plugins, e.g. inputs.http, outputs.http and secretstores.http.

telegraf/plugins/inputs/http/http.go

Lines 143 to 149 in 448260a

	for k, v := range h.Headers {
	if strings.EqualFold(k, "host") {
	request.Host = v
	} else {
	request.Header.Add(k, v)
	}
	}

This PR updates the outputs.influxdb and outputs.influxdb_v2 plugins to bring it inline with the other plugins, i.e. allow setting the Host header using the http_headers config parameter.

Checklist

• No AI generated code was used in this PR

Related issues

resolves #14482

[powersj]

Hi,

Can you please file an issue and detail why a user would want to set the headers please?

Thanks

edit: if you could just file an issue so we have something to track this with, I would appreciate it.

[slai]

@powersj thanks for looking at this so quickly! I've filed #14482 to describe the use case.

[powersj]

Thank you for taking the time to put this up!