Support "hooks" in build tasks

[michaelsauter]

Currently there is no control over what gets executed in builder tasks (such as ods-build-go). While this is by design (to prevent customisations that are not predictable) it is probably too restrictive. For example, given we have a solution for #135, users might want to run database migrations before running the integration test suite. With the current design, this would not be possible with the official task and a custom task would be needed.

One option could be to provide more parameters that allow to run scripts before/after certain steps in the task, such as before running tests (e.g. params.script-before-tests) and after running tests (e.g. params.script-after-tests). While this would allow users to run arbitrary things in the task, it would not allow them to bypass the default behaviour without doing crazy stuff.

Thoughts?

FYI @felipecruz91 @renedupont

[felipecruz91]

That could be a good starting point. I assume it will be quite simple at the beginning, by just running an entrypoint bash script, e.g. script-before-tests.sh and script-after-tests.sh where users would put their logic in there, right?

[michaelsauter]

Correct. If we wanted to, we could even auto-detect such scripts instead of having many parameters. Not sure which option is better ... the params at least would provide clear documentation.

[felipecruz91]

I'd rather have them explicitly via parameters