server/api: add an API to configure failpoints in runtime (#3488)

[sticnarf]

What is changed and how it works?

Cherry pick #3488. Some integration tests depend on setting failpoints at runtime. We need this feature on release-4.0 to do integrations tests for 4.0.x.

Check List

Tests

• Manual test (add detailed scripts or steps below)

First set GO_FAILPOINTS="github.com/tikv/pd/server/api/enableFailpointAPI=return" environment variable to enable this API.

Then, we can run HTTP requests like this to set failpoints:

curl -X PUT -d "return" http://{PD_ADDR}:2379/pd/api/v1/fail/github.com/tikv/pd/server/tso/systemTimeSlow

And we can also get the enabled failpoint list:

❯ curl http://{PD_ADDR}:2379/pd/api/v1/fail/
github.com/tikv/pd/server/api/enableFailpointAPI=return
github.com/tikv/pd/server/tso/systemTimeSlow=return

Code changes

• Has HTTP API interfaces change

Release note

NONE

[codecov]

Codecov Report

Merging #3809 (fab0dd9) into release-4.0 (85a49d5) will decrease coverage by 2.50%.
The diff coverage is 69.15%.

@@               Coverage Diff               @@
##           release-4.0    #3809      +/-   ##
===============================================
- Coverage        77.16%   74.66%   -2.51%     
===============================================
  Files              204      211       +7     
  Lines            21940    19940    -2000     
===============================================
- Hits             16931    14888    -2043     
+ Misses            3724     3715       -9     
- Partials          1285     1337      +52     

Flag	Coverage Δ
unittests	74.66% <69.15%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
client/metrics.go	100.00% <ø> (ø)
pkg/apiutil/apiutil.go	61.90% <ø> (-5.45%)	⬇️
pkg/cache/cache.go	0.00% <ø> (ø)
pkg/cache/fifo.go	100.00% <ø> (ø)
pkg/cache/lru.go	76.74% <ø> (-3.62%)	⬇️
pkg/cache/two_queue.go	61.11% <ø> (-5.56%)	⬇️
pkg/codec/codec.go	77.46% <ø> (-1.11%)	⬇️
pkg/component/manager.go	77.94% <ø> (-3.08%)	⬇️
pkg/dashboard/adapter/redirector.go	93.33% <ø> (-0.90%)	⬇️
pkg/dashboard/keyvisual/input/core.go	33.33% <ø> (ø)
... and 372 more

---

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[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 1af22a4

[ti-chi-bot]

@sticnarf: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

@sticnarf: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.