Support customizing port numbers
Setting up multiple web UI instances on the same host can be useful for development, e.g. for implementing the round robin worker. Actually one can right now start multiple web UIs quite easily by adjusting the environment variables
OPENQA_CONFIG. The only problem is that openQA's internal clients for IPC via HTTP would still use the default port numbers. So this last detail should be fixed. I propose allowing to set an environment variable
OPENQA_BASE_PORT which defines the base port used by the main web UI. Additional services would use a fix offset added to that port.
If this kind of setup is also desired for non-development purposes we can also consider adding a
base_port field to the config file.