feat(analysis): add Apache SkyWalking as metrics provider

[kezhenxu94]

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional with a list of types and scopes found here, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234".
• I've signed my commits with DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My builds are green. Try syncing with master if they are not.
• My organization is added to USERS.md.

[github-actions]

Go Published Test Results

1 859 tests   1 859 ✔️  2m 31s ⏱️
   113 suites         0 💤
       1 files           0 ❌

Results for commit 2996abc.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

Base: 81.60% // Head: 81.52% // Decreases project coverage by -0.09% ⚠️

Coverage data is based on head (2996abc) compared to base (d7df8b3).
Patch coverage: 59.49% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2491      +/-   ##
==========================================
- Coverage   81.60%   81.52%   -0.09%     
==========================================
  Files         130      131       +1     
  Lines       19483    19562      +79     
==========================================
+ Hits        15900    15947      +47     
- Misses       2766     2795      +29     
- Partials      817      820       +3     

Impacted Files	Coverage Δ
utils/analysis/factory.go	91.12% <0.00%> (-1.30%)	⬇️
metricproviders/skywalking/skywalking.go	61.84% <61.84%> (ø)

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[kezhenxu94]

Tests seem to be flaky, it can pass in my local machine

[github-actions]

E2E Tests Published Test Results

    2 files      2 suites   1h 41m 46s ⏱️
  96 tests   86 ✔️ 3 💤 7 ❌
200 runs  187 ✔️ 6 💤 7 ❌

For more details on these failures, see this check.

Results for commit 2996abc.

♻️ This comment has been updated with latest results.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

No Coverage information
0.0% Duplication

[todaywasawesome]

LGTM

I know we want to move metrics providers out of rollouts but until we're ready to do that, I think we should be very permissive on these kinds of merges.

[harikrongali]

#2514 solves supporting additional metrics providers without adding them to rollout source. @zachaller can confirm if we need this PR?

[zachaller]

#2514 solves supporting additional metrics providers without adding them to rollout source. @zachaller can confirm if we need this PR?

Even though plugin system has just been merged it also is not 100% complete yet though it is close. I still do plan and think that merging this is the correct thing to do for a few reasons. One being that a good majority of users of this metric provider will be APISIX traffic router users the two projects are both under the apache foundation and share the same user base.

We have already merged APISIX before any plugin systems where in place and this PR was also submitted way before any plugin systems where in place as well. Therefore I do think it makes sense to allow this PR through however this will probably be the last one that goes straight into the main project.

I do think though that even with plugins having some form of graduation type system in place where plugins can gain enough traction and or meet some requirements that they move into "core" project however all that has not really been decided yet.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
3 Code Smells

No Coverage information
4.5% Duplication

[kezhenxu94]

@zachaller thank you for helping to resolve the conflicts and merging the pr!