How to write a Telegraf Processor to change the hostname (fot GCE for instance)

I am using Telegraf to collect docker and system metrics (so far). It is deployed on a swarm on Google Cloud.

If I use the official plugins I don’t have the right hostname (as in a GCE swarm). On my custom plugins, I simply launch a request to (go code):

	req, err := http.NewRequest("GET", "", nil)
	if err != nil {
		return "", err
	req.Header.Set("Metadata-Flavor", "Google")

It works but I wish to use the official plugins (docker and system at least) as much as possible.

It seems that rewriting the hostname could be a task done by a Processor (as presented in Aggregator and Processor Plugins | InfluxData Documentation Archive).
But I can’t find any example of processors that could help me create my own.

So I have 3 questions :
1- can a processor solve my problem, ie rewrite the hostname tag (which is added by telegraf if I am not mistaken)
2- can a processor be a program (in my case in go) ?
3- is there such an example (in any language) and where ?

@Nilct I’ve done this in Kubernetes by using the Downward API to inject a HOSTNAME into the telegraf container. It looks like you could do the same with that gocode you list above. I use that env to explicitly set the the [agent]hostname = "$HOSTNAME" in the config file. Does that work for for you?

That would could work on our pods (the deployment depends on k8s config files) but we also have containers on workers deployed via docker-compose on a swarm (the container is built on the manager then deployed on any worker as needed).

I will nevertheless investigate this API, thanks !

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