marathon-consul with consul-template example

[scalp42]

Any chance the repo could show an example on how to use it lets say with consul-template for example ?

I'm assuming we need to grab taskStatus in the JSON store:

{{with $t := key "marathon/TASKNAME/tasks/SUBTASKNAME" | parseJSON}}
{{if $t}}
{{$t.taskStatus}}
{{end}}
{{end}}

But how do we iterate the tasks in the KV ? marathon-consul seems to store a single key as well as a folder:

MARATHON/
  TASKNAME/
  TASKNAME

Thanks in advance for chiming in.

[stevendborrelli]

This is what we use in haproxy-consul:

https://github.com/CiscoCloud/haproxy-consul/blob/master/template/marathon.tmpl

Just as an FYI, we are moving towards replacing the marathon-> marathon-consul -> consul setup with traefik.

[scalp42]

Thanks a lot @stevendborrelli

Any chance you could give some insight related to the move to traefik ? I'm assuming less moving parts but would love to know.

[stevendborrelli]

Sure:

1. consul-template with many watches (say over 150) can take down a consul cluster
2. There were instances where consul-template put out an invalid haproxy.cfg, and it was hard to monitor those situations. (We had to update the template to fix things like missing task id's, etc.)
3. traefik has a UI and API
4. dynamic reloads without having to restart haproxy and deal with possible lost connections
5. Consul templates get complicated to write and debug as needs get more complex.
6. It was kind of hack-ish to put discovery data in consul k/v instead of consul service discovery. We had to do this because mesos didn't expose good port mapping data. (The discoveryinfo protobufs that just landed in Mesos and mesos-consul 0.3 help here)

[scalp42]

Fair enough! Greatly appreciated @stevendborrelli

[scalp42]

Digging in traefik, unfortunately only http loadbalancing is supported (vs tcp mode of haproxy).