API Custom error codes

[aravindavk]

REST API status code can be used to identify the request is failed or not. Granular error code should be available in error response.

General HTTP status codes

• Success: 200, 201, 204
• Resource not found: 404
• Invalid input/Bad request: 400
• Conflict/Busy: 409
• API error from server: 500

Custom error codes are required for the following(incomplete list, need to identify other failure scenarios)

• Peer add:
  • Peer already Exists
• Peer Remove
  • Peer not found(HTTP status 404)
• Volume Create
  • Volume already exists
• Volume Start
  • Volume not found
  • Volume already started
• Volume Stop
  • Volume not found
  • Volume already stopped
• Volume Delete
  • Volume not found

[aravindavk]

@sac @prashanthpai @kshlm @Madhu-1 please add if any other error codes are required.

[Madhu-1]

http.StatusUnauthorized http.StatusUnprocessableEntity

[prashanthpai]

http.StatusUnprocessableEntity is hard to get right - it's debatable what it means. We removed it a while ago. I'd simply use 400 instead.

I want StatusUnprocessableEntity to mean that JSON parsing failed but that's not what it's intended for: https://httpstatuses.com/422

[Madhu-1]

@prashanthpai AFAIK we are using http.StatusUnprocessableEntity in gd2

./glusterd2/commands/snapshot/snapshot-create.go:		restutils.SendHTTPError(ctx, w, http.StatusUnprocessableEntity, gderrors.ErrInvalidSnapName)
./glusterd2/commands/snapshot/snapshot-activate.go:		restutils.SendHTTPError(ctx, w, http.StatusUnprocessableEntity, err)
./glusterd2/commands/snapshot/snapshot-clone.go:		restutils.SendHTTPError(ctx, w, http.StatusUnprocessableEntity, errors.New("Snapshot name should not be empty"))
./glusterd2/commands/snapshot/snapshot-clone.go:		restutils.SendHTTPError(ctx, w, http.StatusUnprocessableEntity, gderrors.ErrInvalidVolName)

[prashanthpai]

@Madhu-1 Those needs to be changed

[prashanthpai]

See https://github.com/gluster/glusterd2/issues/611

[Madhu-1]

@prashanthpai agreed.

[sac]

@aravindavk looks okay to me. I'll check the library once and get back to this.

[atinmu]

@Madhu-1 What more work is pending here?

[atinmu]

Not a blocker for GCS/1.0 from the revised MVP perspective.