Tracking issue for the HTTP SDK

[JmPotato]

Development Task

As pingcap/tidb#35319 mentioned, providing a unified PD HTTP API SDK has become an urgent need. With this means, it could be easier for us to control and observe the use of the PD HTTP API in general.

• Basic implementation. client: introduce the HTTP client #7304
• Fulfill supported interfaces.
  • client/http: implement more HTTP APIs #7371
  • client/http: encapsulate rule-related PD HTTP interfaces #7397
  • client/http: pass res interface into respHandler #7404
  • client/http: implement more rule and batch related interfaces #7430
  • client/http: use KeyRange to differentiate the encoding format of the key #7449
  • client/http: add GetHistoryHotRegions interface and more tests #7453
  • client/http: implement the marshaler interfaces for Rule/RuleOp #7462
• Backoff mechanism.
  • client/http, retry: support backoffer in HTTP client #7680
  • http/client, retry: copy a new Backoffer for each request #7684
• Integrate with other components.
  • Support to integrate with the PD HTTP client client-go#1049
  • *: integrate PD HTTP client to the store helper pingcap/tidb#48276
  • *: further adaptation to PD HTTP client pingcap/tidb#48606
  • infosync: integrate PD HTTP client into the label manager pingcap/tidb#48738
  • infosync: integrate PD HTTP client into the placement manager pingcap/tidb#48858
  • infosync: fully integrated PD HTTP client into InfoSyncer pingcap/tidb#49006
• Integration tests.
  • http: init NewDefaultPDServiceDiscovery and refine http client tests #7744
• pd ctl
  • ctl: replace cluster info with HTTP SDK #7605
  • pd-ctl: avoid initializing a new PD client for each cmd execution #7804
  • ctl: replace config with HTTP SDK #7834
  • ctl: replace doRequest with HTTP client to get health status #8212
  • ctl: replace gc_safepoint call with PD HTTP SDK #8504
• tools
  • tools/api: replace client to pd http client #7574
  • tools/simulator: add store api and replace simulator http with SDK #8245