fix(kuma-cp): graceful components #4277
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Signed-off-by: Jakub Dyszkiewicz <jakub.dyszkiewicz@gmail.com>
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Codecov Report
@@ Coverage Diff @@
## master #4277 +/- ##
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Coverage 55.68% 55.69%
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Files 935 935
Lines 56402 56421 +19
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+ Hits 31410 31424 +14
- Misses 22513 22518 +5
Partials 2479 2479
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michaelbeaumont
approved these changes
May 13, 2022
lobkovilya
reviewed
May 16, 2022
Signed-off-by: Jakub Dyszkiewicz <jakub.dyszkiewicz@gmail.com>
lobkovilya
approved these changes
May 16, 2022
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Summary
To implement a graceful shutdown, I had to disable signal propagation from Kuma DP to Envoy. That means that we need to take care of sending the signal ourselves. This has a disadvantage that if we won't do this, Envoy (and other subprocesses) will still be running. This is not a problem on Kubernetes since the whole Pod will go down, but it is a problem on VMs.
There was a race that we were not waiting until all components are stopped. This could result in stopping Kuma DP process without closing context that is passed to Envoy command which results in not sending SIGTERM.
I implemented
GracefulComponentthat adds additional optional logic of waiting until the component is finished. The logic is specific to every component. In the case of Envoy and CoreDNS, the main process waits until the command finish.I considered adding
WaitForDonetoComponent, but this would result in empty implementations for tens of components, which is also not that relevant if they are not manage external resources. I expect that moving this toComponentwill be done in #1001Issues resolved
Not reported, I noticed it while testing.
Documentation
No extra docs.
Testing
Backwards compatibility
- [ ] UpdateUPGRADE.mdwith any steps users will need to take when upgrading.