Consul Service Data in Nomad Job

[dma...@istreamplanet.com]

Sorry if this is obvious.  I thought it would be but I haven't been able to find the answer yet.

I've got two services in docker, kafka & zookeeper,  and one (kafka) needs to know the IP address & port number of the other (zookeeper).  The kafka container expects the zookeeper details as environment variables.  I figure the zookeeper details are already in consul, so I should be able to feed that into the env vars in the job file.  Something like

env {

  KAFKA_ZK_HOST = "$consul.service.zookeeper.host"

  KAFKA_ZK_PORT = "$consul.service.zookeeper.port"

  ...

}

Am I totally barking up the wrong tree?

How do I get details about one job/task/allocation into the definition of another job/task?

Thanks!

-Dylan

[Justin DynamicD]

What you want here is a template.  This basically leverages consul-template to create your variables for you ... and as consul-template can do consul lookups ... you're golden.  Try a stanza like this:

template {

data = <<EOH

KAFKA_ZK_HOST="{{range service "zookeeper"}}{{.Address}}{{end}}"

KAFKA_ZK_PORT="{{range service "zookeeper"}}{{.Port}}{{end}}"

EOH

destination = "secrets/file.env"

env = true

}

[dma...@istreamplanet.com]

Cool!  Thanks!

Are you saying I use consul-template to build my job file?  And consul-template kicks the job if it detects a change?  Or are you saying if I put your example in my job file, nomad will know what it means?  If the latter, where can I find reference documentation to help me learn how that works?

Thanks again!

-Dylan

[Justin DynamicD]

I'm saying the later:  nomad will know what that means.  It basically leverages consul-template to get the work done.  Basics can be found here:

https://www.nomadproject.io/docs/job-specification/template.html

Thing to keep in mind is this is basically using the consul-template code to generate the template data.  Because of that I've found reading the consul-template details to be useful:

https://github.com/hashicorp/consul-template

Hope this helps.

[dma...@istreamplanet.com]

Awesome!  Thanks!