#18670 is a breaking change to the module API function `run_as_background_process`

[reivilibre]

#18670 slated for v1.136.0 unfortunately introduces a breaking change to the run_as_background_process function by making it require a server_name argument.

This function is exported under synapse.module_api so its signature should ideally remain stable. Modules are not expecting to have to pass this new server_name argument and so fail on startup.

This is also making us unable to update matrix.org :-)

[reivilibre]

Perhaps it'd be reasonable to store the active server_name in the logcontext? This would mean it propagates 'for free'.

[devonh]

@MadLittleMods ^

[MadLittleMods]

hmm, that's a subtle interaction 😬 Thanks for finding it early @reivilibre!

It would be nice if run_as_background_process(...) was part of the ModuleApi itself so we could just cover the difference transparently to the downstream users of the module API.

We can always shim the run_as_background_process definition in the module API to have a stub server_name value there and deprecate it in favor of the potential new ModuleApi.run_as_background_process(...)

How does this look? -> #18737

It looks like we already do this for @cached