On 23-01-2018 00:38, Tim Serong wrote:
Hi All, Right now, if you want to debug an mgr python module, you're pretty much restricted to dumping interesting stuff to log files, right? What about if you wanted to run an interactive python debugger? I had two half-formed ideas for this. One is that apparently there's something called prdb, which could theoretically be loaded in an mgr module to enable remote debugging over a socket (although https://pypi.python.org/pypi/rpdb/ says it reroutes stdout and stdin, which I assume might not work given mgr is already eating those -- not sure, haven't had a chance to try it yet).
Even without having the stdout/err it's very useful to be able to stop execution at breakpoints and do a step-by-step execution. I think it should be easy to make prdb to work with ceph-mgr plugins. Thanks for the research.
The second idea was to create a python wrapper which provides a stub implementation of the pieces that ceph-mgr exposes from C++ land (ceph_state, etc.). This would expose some fake cluster state, much as the minion sim thing did in calamari. Then you could (somehow) load/run a mgr python module completely outside mgr to experimentally poke at it. Having typed all that out now, I suspect this might be a PITA to maintain and be ultimately less useful for live debugging that the first half-formed idea, although it might be interesting for unit testing.
I think this idea is also very useful but for a different use-case like unit/functional testing without having to start a Ceph cluster. This way we could add unit tests to the ceph-mgr plugins and run them along with the already existing tests.
Any thoughts on whether any of the above is worth pursuing? Thanks, Tim
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