v1.11.0: VOMS AA should check the configuration is valid at startup

[jouvin]

I spent several hours trying to understand why voms-proxy-init was unable to check the VOMS AC for the VO. It turned out to be caused by a typo in the VOMS AA configuration with the variable used to defined the VO (VOMS_AA_VO) being mispelled as VOMS_AA_V0 (ending character being a zero instead of 0 ) in the environment file. As a result the vo-name property was "undefined" (defined as ${VOMS_AA_VO} in our case).

IMO, it makes no sense to try to run the service without the vo-name property defined to a sensible value. It would be much easier to spot a misconfiguration if the service was refusing to start when it is not the case. Trivial checks for the vo-name value validity may include:

• the value is not empty
• the value is not starting with a $
• the value is not the default value defined in the default application.yml. If MR Update default VOMS AA application.yml #919 is accepted, the default value would be undefined.

Similarly, if MR #919 is accepted, it would be good to do the same check for host property (unless it has an undocumented default in the code). For the port property, the default value is a string instead of a number and raises an explicit exception so the check is less needed but may be good too.