terraform-template-renderer
Provides a ruby executable which will take a path to an ERB template as it's only positional argument and render that with a json blob passed in to STDIN. The keys in the json blob will be used as instance variable names to use in the template.
The result will be returned inside a json blob with a single key, the name of which is rendered.
For example if your template is
Hello <%= @my_key %>!
And you execute the command as:
echo '{ "my_key": "dear reader" }' | template_renderer path_to_my_template
You will produce
{ "rendered": "Hello dear reader!" }
The purpose for this strange behaviour is to be a terraform external provider to render arbitrarily complex templates, terraform passes in the variables to render as a json blob to stdin as described above and expects a json blob back.