[Docker Plugin] add server hostname for each docker measurements

[aaronjheng]

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[sparrc]

@aaronjheng I'm not sure this is a good idea. By default docker randomizes the name of the container, which means that every launched container will have a new name and the potential series cardinality is infinite.

When talking about influxdb, the database can't handle an infinite number of possible tag/value combinations.

You will need to workaround this using docker labels or other means.

[aaronjheng]

@sparrc Thanks for replying. What I want to record is the host of docker engine, not the container.

[sparrc]

I see, maybe I'm misunderstanding something then, is that different than the built-in telegraf host tag? Can you explain exactly what info.Name is? linking to some documentation would be extra helpful

[aaronjheng]

is that different than the built-in telegraf host tag?

Yes. In my use case, the telegraf program and the target docker-engine are in different servers. So the built-in telegraf host tag is not the docker-engine's host.

Can you explain exactly what info.Name is?

I can't find any specific description about this Info struct. But after digging some source code. I find this https://github.com/docker/docker/blob/master/daemon/info.go:

hostname := ""
if hn, err := os.Hostname(); err != nil {
    logrus.Warnf("Could not get hostname: %v", err)
} else {
    hostname = hn
}
v.Name = hostname

So, I assume that info.Name means the hostname of the docker engine's host.

[aaronjheng]

Ping

[sparrc]

Looks good to me, but can you make the tag more descriptive? I'd suggest docker_engine_host but I'll leave it up to your judgement

[aaronjheng]

Sounds great! In docker context, engine_host is enough.