Consul-template: Generating a comma-separated list of node names from a service

Created on 29 Jul 2015 · 3Comments · Source: hashicorp/consul-template

I'm trying to generate a config file for Icinga, and at one point I need a comma-separated list of nodes, without a trailing comma.

It feels as though something like this should work;

{{define "NODES"}}{{range service "loadbalancer" "any"}} {{.Node}}{{end}}{{end}}
{{template "NODES" | split " " | join "," }}

But, that gives the error: unexpected "|"

Is there a way to do this without writing a plugin?

Source

digitalronin

Most helpful comment

Thanks so much, that's just what I needed. This works;

{{range $index, $service := service "loadbalancer" "any"}}{{if ne $index 0}},{{end}}{{.Node}}{{end}}

It's pretty fugly though.

digitalronin on 29 Jul 2015

👍3

All 3 comments

Hi @digitalronin

There is no concept of a map function in go's template language (which is what you're trying to do here). Users have found success with the following in other tickets: https://github.com/hashicorp/consul-template/issues/263#issuecomment-97074185.

I'm going to close this issue since there really isn't a good solution (but there are good workarounds), but I'm more than willing to continue discussion.

sethvargo on 29 Jul 2015

Thanks so much, that's just what I needed. This works;

{{range $index, $service := service "loadbalancer" "any"}}{{if ne $index 0}},{{end}}{{.Node}}{{end}}

It's pretty fugly though.

digitalronin on 29 Jul 2015

👍3

https://groups.google.com/forum/#!topic/consul-tool/j8O9UPOqfMA
Looks like they allow conditional comma placement. Would this be a good solution? Separating the data flow and control flow is always preferred. So python will have service lookup and json load, while json file dumps everything from consul.