tripleo-docs: 'tox -e docs' fails No such config value: mermaid_output__fmt on main branch

[John Fulton]

Unable to get green zuul of docs patches because even the master branch fails openstack-tox-docs with the following:

looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 2%] ci/baremetal_jobs
writing output... [ 4%] ci/chasing_promotions
writing output... [ 6%] ci/check_gates
writing output... [ 8%] ci/ci_primer
writing output... [ 10%] ci/content_provider_jobs
writing output... [ 12%] ci/dlrn-promoter-overview
writing output... [ 14%] ci/emit_releases_file
writing output... [ 16%] ci/index
writing output... [ 18%] ci/reproduce-ci
writing output... [ 20%] ci/ruck_rover_primer
writing output... [ 22%] ci/stages-overview

Exception occurred:
  File "/home/zuul/src/opendev.org/openstack/tripleo-docs/.tox/docs/lib/python3.8/site-packages/sphinx/config.py", line 257, in __getattr__
    raise AttributeError(__('No such config value: %s') % name)
AttributeError: No such config value: mermaid_output__fmt
The full traceback has been saved in /tmp/sphinx-err-hh745qe2.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
ERROR: InvocationError for command /home/zuul/src/opendev.org/openstack/tripleo-docs/.tox/docs/bin/sphinx-build -a -E -W -d doc/build/doctrees --keep-going -b html doc/source doc/build/html (exited with code 2)
docs finish: run-test after 4.63 seconds
docs start: run-test-post
docs finish: run-test-post after 0.00 seconds
___________________________________ summary ____________________________________
ERROR: docs: commands failed

[John Fulton (jfulton-org)]

https://review.opendev.org/c/openstack/tripleo-docs/+/776698

Reproducer ^ the above should result in a green openstack-tox-docs but it will not

[John Fulton (jfulton-org)]

https://github.com/mgaitan/sphinxcontrib-mermaid/issues/66

[John Fulton (jfulton-org)]

https://github.com/mgaitan/sphinxcontrib-mermaid/commit/42e4b0f1079cb34b90f42e2b274e338326894fbc

[John Fulton (jfulton-org)]

I made ps1 of the following to reproduce the bug:

 https://review.opendev.org/c/openstack/tripleo-docs/+/776698

It then ended up being green. I suspect it used sphinxcontrib-mermaid 0.6.2 which fixed the problem

 https://github.com/mgaitan/sphinxcontrib-mermaid/commit/42e4b0f1079cb34b90f42e2b274e338326894fbc

I ended up updating ps2 of the same patch to contain a simple fix (avoid 0.6.1).

 https://review.opendev.org/c/openstack/tripleo-docs/+/776698/2/doc/requirements.txt

[John Fulton (jfulton-org)]

another fix https://review.opendev.org/c/openstack/tripleo-docs/+/775728

[John Fulton (jfulton-org)]

We have green docs builds now. sphinxcontrib-mermaid 0.6.2 doesn't have the issue and will get pulled in automatically as it's newer.

So this bug has gone away. It was never really a TripleO bug but a tripleo-ci bug only as a result of the dependency but we don't seem to have to do anything extra about it as the fix is getting to our CI.