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Khepri: Mark khepri_db feature flag as stable #12682

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@dumbbell dumbbell commented Nov 7, 2024

Why

The intent is to have it stable and enabled by default for new deployment in RabbitMQ 4.1.x.

To prepare for this goal, it is time to mark the feature flag as stable to let us iron out the library and its integration into RabbitMQ.

This is not a commitment at this stage: we will revisit this near the beginning of the release cycle and commit to it or revert to experimental.

@dumbbell dumbbell self-assigned this Nov 7, 2024
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch 3 times, most recently from 0ae5831 to dffcf0c Compare November 11, 2024 11:31
@mergify mergify bot added the make label Nov 11, 2024
@michaelklishin michaelklishin changed the title Khepri: Mark khepri_db as stable 4.1: Khepri: Mark khepri_db feature flag as stable Nov 13, 2024
@michaelklishin michaelklishin added this to the 4.1.0 milestone Nov 13, 2024
@dumbbell dumbbell changed the title 4.1: Khepri: Mark khepri_db feature flag as stable Khepri: Mark khepri_db feature flag as stable Nov 13, 2024
@mergify mergify bot added the bazel label Nov 14, 2024
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch from 65d2040 to cd02f61 Compare November 14, 2024 10:36
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch from 63988af to 36a8cc8 Compare December 2, 2024 13:38
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch from 36a8cc8 to 473bf7f Compare December 18, 2024 13:52
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch 4 times, most recently from 247a8f0 to e490378 Compare January 15, 2025 20:26
dumbbell and others added 4 commits January 21, 2025 15:51
[Why]
When running mixed-version tests, nodes 1/3/5/... are using the primary
umbrella, so usually the newest version. Nodes 2/4/6/... are using the
secondary umbrella, thus the old version.

When clustering, we used to use node 1 (running a new version) as the
seed node, meaning other nodes would join it.

This complicates things with feature flags because we have to make sure
that we start node 1 with new stable feature flags disabled to allow old
nodes to join.

This is also a problem with Khepri machine versions because the cluster
would start with the latest version, which old nodes might not have.

[How]
This patch changes the logic to use a node running the secondary
umbrella as the seed node instead. If there is no node running it, we
pick the first node as before.

V2: Revert part of "rabbitmq_ct_helpers: Fix how we set
    `$RABBITMQ_FEATURE_FLAGS` in tests" (commit
    57ed962). These changes are no
    longer needed with the new logic.

V3: The check that verifies that the correct metadata store is used has
    a special case for nodes that use the secondary umbrella: if Khepri
    is supposed to be used but it's not, the feature flag is enabled.
    The reason is that the `v4.0.x` branch doesn't know about the `rel`
    configuration of `forced_feature_flags_on_init`. The nodes will
    have ignored thies parameter and booted with the stable feature
    flags only.

    Many testsuites are adapted to the new clustering order. If they
    manage which node joins which node, either the order is changed in
    the testcases, or nodes are started with only required feature
    flags. For testsuites that rely on peer discovery where the order is
    unknown, nodes are started with only required feature flags.
[Why]
The intent is to have it stable and enabled by default for new
deployment in RabbitMQ 4.1.x.

To prepare for this goal, it is time to mark the feature flag as stable
to let us iron out the library and its integration into RabbitMQ.

This is not a commitment at this stage: we will revisit this near the
beginning of the release cycle and commit to it or revert to
experimental.
@dumbbell dumbbell force-pushed the mark-khepri_db-as-stable branch from e490378 to 5fa1293 Compare January 21, 2025 15:03
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3 participants