Escape percent character in Hiera

Question

We're automatically deploying readiness checks on our servers. The checks are defined in Hiera and deployed with Puppet. One of these checks involves a curl command that should return the HTTP status code:

curl -sSLI -o /dev/null -w '%{http_code}' "https://$(hostname -f)/"

However, Hiera interpolates %{...} expressions, so the statement is rendered as

curl -sSLI -o /dev/null -w '' "https://$(hostname -f)/"

and the check fails.

Escaping the percent character or a curly bracket with a backslash doesn't seem to work, neither does doubling the percent character:

• -w '\%{http_code}' turns into -w '\'
• -w '%\{http_code}' turns into -w '%\{http_code}'
• -w '%%{http_code}' turns into -w '%'

How do I prevent Hiera from trying to interpolate the string %{http_code}?

Answer 1

Unfortunately Hiera doesn't allow escaping interpolation expressions with an escape character. Instead you have to use the literal interpolation function:

curl -sSLI -o /dev/null -w '%{literal('%')}{http_code}' "https://$(hostname -f)/"