GUACAMOLE-2114: Custom base for CATALINA_BASE and GUACAMOLE_HOME

[tiborauer]

Allowing a custom base, rather than the ones randomly created in /tmp, would enable storing the program's data in a user-defined location. This feature would be particularly useful on Kubernetes, where the lifecycle of the program's data independent from that of the program would improve robustness. Also, the program's data could be shared with sidecar containers to extend functionality.

[mike-jumper]

Allowing a custom base, rather than the ones randomly created in /tmp, would enable storing the program's data in a user-defined location. This feature would be particularly useful on Kubernetes, where the lifecycle of the program's data independent from that of the program would improve robustness. Also, the program's data could be shared with sidecar containers to extend functionality.

@tiborauer Can you clarify what sort of use case requires storing CATALINA_HOME and GUACAMOLE_HOME data in a user-defined location? My original thinking behind the randomized bases beneath /tmp was to:

• Ensure the container entrypoint always has control over the contents of these locations (ie: avoid breaking the expectations of the entrypoint).
• Avoid downstream reliance on storing anything in these locations (ie: the container shouldn't rely on state persisting within the container itself).

[tiborauer]

@mike-jumper Thank you for clarifying your motivation! I believe it works very well for isolated Docker-only cases. I am using it in a K8s cluster; however, with somewhat different challenges. Having application data on a pre-specified location (on a persistent volume):

• minimises the downtime when recovering or scaling up
• ensures the availability of application data for diagnostics and debugging
• allows attaching an rsyslog container to collect and process logfiles in a centralised manner

[necouchman]

@tiborauer : Please clean up the commits - you have several Merge commits along with ones from different issues (GUACAMOLE-1746). The only commits present should be ones specifically for the GUACAMOLE-2114 issue.