Rudder

So, after some discussion on the suject:

- variables were defined with a "variable from command". So likely something changed in that command output,
- undefined variables are silently not expanded by cfengine.

We need to address these two problems.

For the first one, we can add a check in all "variable from ..." to validate that after variable definition, the variable is ACTUALLY defined. CFEngine doesn't help for that, but we could exploit some trick (predefined variable to some string like "the variable 'XXXX' is not correctly defined" (also usable as an understandable error message for human where the variable will be used), check that it's not that anymore after method exec)

For the second, we need a definitive solution to avoid that class of bug. I don't see any other solution than "rudder lang" (long term) and "finding a way to change that behavior in cfengine" (short term, but perhaps out of reach).