JoshRodstein / consul-template-by-example

consul-template-by-example

Consul template: By Example

This is a very simple example shows how to use consul and consul-template to get data in and out, and how to handle missing and default values. The consul setup is only for development purposes.

Download this repository here

Set-up the tools

Run both shell scripts (setup.sh and setup-consul.sh) to get the tools consul and consul-template. The install examples assume linux but this could be any supported platform as long as the tools are installed in your path.

Start/Spawn Consul

consul agent -dev &

There's an example template file called miss.tpl. This looks like:

Key:Foo:{{key "foo"}}
MissingKey:{{if keyExists "MissingKey"}}{{key "MissingKey"}}{{else}}nothing{{end}}
DefaultValue:{{keyOrDefault "Duffer" ""}}

Consul-template uses the Go templating format- curly brackets the rest of the file is treated as text. The first line is a regular KV retrieval, the second line shows how to cope with missing values and the last line for default values.

First we'll add some data to Consul.

consul kv put foo bar

Then when we run consul-template:

consul-template -template miss.tpl:miss.out -once

The -once option "Do not run the process as a daemon".

Check the contents of the miss.out file.

Key:Foo:bar
MissingKey:nothing
DefaultValue:

Then we'll add a value for MissingKey variable.

consul kv put MissingKey Time

and retry: consul-template -template miss.tpl:miss.out -once

miss.out now becomes:

Key:Foo:bar
MissingKey:Time
DefaultValue:

So there you have it a pretty basic example for using some of the basics behind consul and consul-template as a KV store.