Add Ulimit configuration option to Docker executor
What does this MR do?
This adds the option to configure Ulimit values for Docker executors, similar to "docker run --ulimit". This expands on a previous (but stale) Merge Request: !1957 (closed) Some documentation has been added.
Why was this MR needed?
I need this option to run tests with some hard limits lifted. More cases are listed in the issue #4482 (closed) including ZenDesk references.
What's the best way to test this MR?
Change the ulimit values and observe using "ulimit -a" in a linux container. Or: Have an application that steps "beyond" standard values, e.g. by using mlockall() for more than the standard 64 KB (on my system). This does not work and the application outputs an error. When adding the capability IPC_LOCK and setting the ulimit "memlock" to "-1:-1" (=no limit) the error goes away.