[Why]
The "Feature flags" admin section had several issues:
* It was not designed for experimental feature flags. What was done for
RabbitMQ 4.0.0 was still unclear as to what a user should expect for
experimental feature flags.
* The UI uses synchronous requests from the browser main thread. It
means that for a feature flag that has a long running migration
callback, the browser tab could freeze for a very long time.
[How]
The feature flags table is reworked and now displays:
* a series of icons to highlight the following:
* a feature flag that has a migration function and thus that can
take time to be enabled
* a feature flag that is experimental
* whether this experimental feature flag is supported or not
* a toggle to quickly show if a feature flag is enabled or not and let
the user enable it at the same time.
For stable feature flags, when a user click on the toggle, the toggle
goes into an intermediate state while waiting for the response from the
broker. If the response is successful, the toggle is green. Otherwise it
goes back to red and the error is displayed in a popup as before.
For experimental feature flags, when a user click on the toggle, a popup
is displayed to let the user know of the possible constraints and
consequences, with one or two required checkboxes to tick so the user
confirms they understand the message. The feature flag is enabled only
after the user validates the popup. The displayed message and the
checkboxes depend on if the experimental feature flag is supported or
not (it is a new attribute of experimental feature flags).
The request to enable feature flags now uses the modern `fetch()` API.
Therefore it uses Javascript promises and does not block the main
thread: the UI remains responsive while a migration callback runs.
Finally, an "Enable all stable feature flags" button has been added to
the warning that tells the user some stable feature flags are still
disabled.
V2: Pause auto-refresh while a feature flag is being handled. This fixes
some display inconsistencies.
[Why]
The previous implementation was using the blocking `is_enabled/1` API.
This meant that if a feature flag was being enabled and the enable
callback took time, the CLI's `list_feature_flag` command or any use of
the management UI would block until the feature flag was enabled.
[How]
`get_state/1` now uses the non-blocking API. However it returns a now
possible value: `state_changing`.
[Why]
Durint the development of Khepri, it was difficult to communicate that
it was unsupported in RabbitMQ 3.13.x but was then supported in 4.0.x
even though it was still experimental.
[How]
The feature flag definition now exposes that support level in a now
attribute called `experiment_level`. It can be `unsupported` or
`supported`.
We can use this now attribute in the CLI or the web UI to convey the
level of support to the end user.
In the future, we could imagine that an experimental feature flag
becomes abandoned, where upgraded from a node that has it enabled to a
version that marks the feature flag as abandoned is not possible.
If a test or doc file changes, we do not need
to trigger a new alpha build, or at least
we should first see some evidence that we do.
Author: Michael Klishin <michaelklishin@icloud.com>
1. Use Elixir 1.17.x
2. Only run this suite when the management plugin
or web_dispatch source code changes
3. Target relevant branches: main and v4.0.x
Michael Klishin
Jean-Sébastien Pédron
Michael Klishin
markus812498
Diana Parra Corbacho
Michael Klishin
Lois Soto Lopez
GitHub
dependabot[bot]