Add HTTP health check handler for server health monitoring

taeng0204 commented 1 month ago

Added a handler to allow health checks to be performed with plain HTTP GET requests, rather than health checks using rpc.

What this PR does / why we need it: In issue #832 , we needed a health check via HTTP GET or HEAD method because of NCP's load balancer. The existing grpchealth could not satisfy this, so we implemented a separate handler. This allows us to check the health of a specific service via the path /healthz/ and the health of a specific service via the query service=<serviceName>. Which issue(s) this PR fixes:

Fixes #832

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Additional documentation:

Checklist:

[x] Added relevant tests or not required
[x] Didn't break anything

Summary by CodeRabbit

New Features
- Introduced health check functionality, allowing clients to verify the server's status via HTTP GET requests.
- Added an HTTP handler for health checks, enhancing service reliability and monitoring.
Bug Fixes
- Improved error handling for unsupported request methods.
Tests
- Renamed existing health check test for clarity.
- Added multiple new tests for both gRPC and HTTP health checks to ensure comprehensive coverage.

CLAassistant commented 1 month ago

All committers have signed the CLA.

coderabbitai[bot] commented 1 month ago

Walkthrough

The recent changes introduce a straightforward HTTP health check endpoint to the server, enhancing service observability. A new handler responds to GET requests, providing an accessible way for uptime checkers to monitor service health. This feature complements existing gRPC health checks, ensuring a versatile and user-friendly monitoring solution.

Changes

File(s)	Change Summary
`server/rpc/health/health.go`, `server/rpc/httphealth/httphealth.go`	Introduced HTTP health check handlers and response structs for health status.
`server/rpc/server.go`	Refactored health check handling to improve code clarity and modularity.
`test/integration/health_test.go`	Renamed gRPC health check test and added new HTTP health check tests for comprehensive coverage.

Assessment against linked issues

Objective	Addressed	Explanation
Add Plain HTTP Health Check Endpoint (#832)	✅

🐰 In the meadow, we hop with glee,
A health check now waits, as easy as can be!
With GET requests, our status is clear,
Uptime checkers smile, their worries disappear!
So bounce along, in code we trust,
For healthy servers, we must adjust! 🌱

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krapie commented 1 month ago

@taeng0204 Could you please sign the CLA? Also you need to lint the code to pass the CI.

taeng0204 commented 1 month ago

@krapie There are a lot of lint errors that are not related to the file I'm dealing with, so I didn't find it, sorry. ~For clean commits, I modified the pushed commits with amend and force since it's just me working on the branch, is that okay?~ I didn't realize you were using squash merge...!

taeng0204 commented 1 month ago

My real email address and the email info in the commit didn't match, which is why the CLA wasn't working... I'm so sorry😭

krapie commented 1 month ago

@taeng0204 If you finish your work, please re-request review.

taeng0204 commented 1 month ago

@krapie I've completed it to requirements. Thanks for your help. ☺️ Does Yorkie have any documentation or guidelines for writing test code?

krapie commented 1 month ago

@taeng0204 There are two things that I want to share:

I think we need to also support HTTP HEAD method to use UptimeRobot. We are currently using the free version, and it only supports HTTP HEAD method (I thought GET method was also supported on free tier)
We need to think about the path /healthz/ again in cluster condition. In yorkie-cluster, envoy proxy uses the same path for their own health check. So we have to explicitly route to our own Yorkie service, or change the path to something like /yorkie.v1/healthz.

taeng0204 commented 1 month ago

@krapie I've processed it in this branch and created a new PR as we talked about today. Please check it out 😄

yorkie-team / yorkie