Validating ERB templates

Before deploying a template, validate its syntax and render its output to make sure the template is producing the results you expect. Use the Rubyerb command to check Embedded Ruby (ERB) syntax.

ERB validation

To validate your ERB template, pipe the output from the erb command into ruby:

erb -P -x -T '-' example.erb | ruby -c

The -P switch ignores lines that start with ‘%’, the -x switch outputs the template’s Ruby script, and

-T
        '-'

sets the trim mode to be consistent with Puppet’s behavior. This output gets piped into Ruby’s syntax checker (-c).

If you need to validate many templates quickly, you can implement this command as a shell function in your shell’s login script, such as .bashrc, .zshrc, or .profile:

validate_erb() {
  erb -P -x -T '-' $1 | ruby -c
}

You can then run

validate_erb
        example.erb

to validate an ERB template.