VReplication: Support ignoring the source Keyspace on MoveTables cancel/complete

[mattlord]

Description

As noted in the issue you may have a MoveTables workflow running for a long time with the traffic switched so that all traffic is going to the target keyspace. Then at some point someone may delete/decommission the source keyspace as it's no longer needed — before having completed the workflow. If that happens then there's no way to complete the workflow and a number of manual steps would be needed to cleanup the Topo Server and MySQL data associated with the workflow. This PR adds a --ignore-source-keyspace flag to the MoveTables complete, MoveTables cancel, and Workflow delete commands in order to support the cleanup work in these scenarios.

Manual tests:

cd examples/local
alias vtctldclient='command vtctldclient --server=localhost:15999' 

./101_initial_cluster.sh; ./201_customer_tablets.sh; ./202_move_tables.sh; ./203_switch_reads.sh; ./204_switch_writes.sh

for i in 100 101 102; do
        CELL=zone1 KEYSPACE=commerce TABLET_UID=$i ../common/scripts/vttablet-down.sh
done

vtctldclient --action_timeout 30s MoveTables --workflow commerce2customer --target-keyspace customer complete

vtctldclient MoveTables --workflow commerce2customer --target-keyspace customer complete --ignore-source-keyspace

./101_initial_cluster.sh; ./201_customer_tablets.sh; ./202_move_tables.sh; ./203_switch_reads.sh; ./204_switch_writes.sh

for i in 100 101 102; do
        CELL=zone1 KEYSPACE=commerce TABLET_UID=$i ../common/scripts/vttablet-down.sh
done

vtctldclient DeleteKeyspace commerce --recursive --force

vtctldclient --action_timeout 30s MoveTables --workflow commerce2customer --target-keyspace customer complete

vtctldclient MoveTables --workflow commerce2customer --target-keyspace customer complete --ignore-source-keyspace

Related Issue(s)

• Fixes: Feature Request: Add --force flag for MoveTables / Workflow completion #17517

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added: Update docs for https://github.com/vitessio/vitess/pull/17729 website#1938

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 68.08511% with 45 lines in your changes missing coverage. Please review.

Project coverage is 67.47%. Comparing base (965253a) to head (cc3c46e).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtctl/workflow/server.go	75.51%	24 Missing ⚠️
...vtctldclient/command/vreplication/common/cancel.go	0.00%	7 Missing ⚠️
...ctldclient/command/vreplication/common/complete.go	0.00%	7 Missing ⚠️
...ctldclient/command/vreplication/workflow/delete.go	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17729      +/-   ##
==========================================
- Coverage   67.47%   67.47%   -0.01%     
==========================================
  Files        1594     1594              
  Lines      258978   259049      +71     
==========================================
+ Hits       174746   174785      +39     
- Misses      84232    84264      +32     

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[shlomi-noach]

Looks like a good candidate for errgroup, but fine as it is.

[mattlord]

Sure, I can switch that over. I had only moved this code in the PR which is why I left it as-is.

[shlomi-noach]

Then leave it as it is.

[mattlord]

I went ahead and migrated it since I was going to merge in origin/main anyway and thus do another CI run: 7946667

[shlomi-noach]

The suggested approach is "don't bother checking the source". I wonder if the approach should be "try the source if possible but fail gracefully"? Just a thought, not sure if that's desired.

[mattlord]

I thought about that too but opted for this approach in the end so that we don't end up with undefined behavior and unknown state on the source — that is, some things are cleaned up on some shards (whatever was available and did not error at the time).

[shlomi-noach]

That's a good point.