Flag link creation doesn't retry on HTTP 429 (rate_limited) #257

Summary

create-flag-links: true fails silently for some flags when LaunchDarkly returns 429 rate_limited. The flag link requests in internal/ldclient/flag_links.go are not retried. #253 added retry/backoff for the flag listing requests only.

Version

launchdarkly/find-code-references-in-pull-request v2.3.0 (3d0cb58224bc446bd9fe84faab3a1c4d8134cf76). I checked the source of v2.3.3 and flag_links.go still has no retry handling.

What happens

The action emits a warning and moves on, so the job stays green and the flag link is never created:

Warning: Failed to create flag link for test-flag1
[POST https://app.launchdarkly.com/api/v2/flag-links/projects/test/flags/test-flag1] Flag link request failed [status=429]
{"code":"rate_limited","message":"You've exceeded the API rate limit. Try again later."}

Warning: Failed to create flag link for test-flag5
[POST https://app.launchdarkly.com/api/v2/flag-links/projects/test/flags/test-flag5] Flag link request failed [status=429]
{"code":"rate_limited","message":"You've exceeded the API rate limit. Try again later."}

The PR in question removed several flags ("Flag extinct, Removed 7 other flags"), so the action sends a burst of POSTs. The account's rate limit is shared with other CI jobs, so 2 of them were rejected.

Expected behaviour

Flag link requests should handle 429 the same way the flag listing does after #253: honour Retry-After / the rate-limit reset headers, fall back to exponential backoff, and give up after a bounded time. Ideally the action would also:

• space out the requests when quota is nearly exhausted;
• treat 409 (link already exists) as success;
• report a failure summary (or an optional fail-on-flag-link-error input), because the current warning is easy to miss.

Related

#253 - Retry rate-limited flag requests (listing only)