envsubst won't substitute secrets about cloud-builders-community

[kevinblanco]

@jrean based on this documentation you must use _ underscore:

You can also define your own substitutions. User-defined substitutions must conform to the following rules:

Substitutions must begin with an underscore (_) and use only uppercase-letters and numbers (respecting the regular expression _[A-Z0-9_]+). This prevents conflicts with built-in substitutions. To use an expression starting with $ you must use $$. Thus:
$FOO is invalid since it is not a built-in substitution.
$$FOO evaluates to the literal string $FOO.
The number of parameters is limited to 100 parameters. The length of a parameter key is limited to 100 bytes and the length of a parameter value is limited to 4000 bytes.
You can specify variables in one of two ways: $_FOO or ${_FOO}:

Both $_FOO and ${_FOO} evaluate to the value of _FOO. However, ${} lets the substitution work without surrounding spaces, which allows for substitutions like ${_FOO}BAR.
$$ allows you to include a literal $ in the template. Thus:
$_FOO evaluates to the value of _FOO.
$$_FOO evaluates to the literal string $_FOO.
$$$_FOO evaluates to the literal string $ followed by the value of _FOO.

[jrean]

@kevinblanco Thanks! Helpful. Do you mind to update my example ; I can't get it to work right now.