Obsolete archane functionality

[oliver-sanders]

It would make sense to remove cruft and cut down the codebase before we spin up major work on Cylc 8 to make things simpler:

• Part 1 - Remove obsolete commands and modules
• Part 2 - Remove obsolete Cylc configuration & documentation
• Part 3 - Remove outdated back-compat code branches - future work

As the communication protocols are changing we can now drop all back-compat on the network side.

@cylc/core anything controversial, anything missed?

[matthewrmshin]

You can remove the 5to6 tests?

[matthewrmshin]

I'll add most of the suite run database restart upgrade logic.

[kinow]

Great idea @oliver-sanders !!! 🎉

[matthewrmshin]

(Just a few failed tests to sort out. You are almost there.)

[oliver-sanders]

Honestly surprised we had tests for the cylc documentation command.

A few tests left to fix.

[hjoliver]

There's also a "Cylc 6 Migration" section in the User Guide.

[oliver-sanders]

I think it's probably safer to remove functional configurations rather than obsoleting them so that suites refuse to run rather than run with potentially important bits (e.g. script) missing.

@cylc/core With the exception of the renamed metadata entries all the newly obsoleted configurations are functional so should we just remove them instead?

[matthewrmshin]

Agreed. Fail is better than warning in this case. Warnings are just ignored and can cause downstream issues. With the time scale of Cylc 8, we should really aim to provide back compat only for modern Cylc 7 suites. I'd like to draw a line at 7.7 - but happy to stretch it to 7.5.

[oliver-sanders]

There's some old syntax in etc/dev-bin. Are these files used any more?

[matthewrmshin]

Test failing on style.

[hjoliver]

There's some old syntax in etc/dev-bin. Are these files used any more?

I guess you mean defn-order-test.py; that could be removed.