GitHub webhook not refreshing ApplicationSets on branches with slashes

TL;DR

Maintainer rumstead's workaround, verified by reporter pre: in your git generator, use the fully qualified ref, refs/heads/env/dev for branches or refs/tags/v3.14.1 for tags, instead of the short name. Reporter-confirmed root cause and workaround.

Steps

1. Reporter-confirmed root cause and workaround. GitHub sends the full branch ref (refs/heads/env/dev) in the webhook payload, and the ApplicationSet webhook handler misparses refs containing a slash, so the refresh never matches. Maintainer rumstead's workaround, verified by reporter pre: in your git generator, use the fully qualified ref, refs/heads/env/dev for branches or refs/tags/v3.14.1 for tags, instead of the short name. With the qualified ref the webhook matches and refreshes correctly. The underlying parsing bug has a PR upstream, but the qualified-ref form works today.

When to use

You are seeing this: Issue argoproj/argo-cd#15427 (closed, 49 comments): GitHub webhooks stop refreshing ApplicationSets when the tracked branch or tag contains a slash, e.g. env/dev. Use this skill when you run into "GitHub webhook not refreshing ApplicationSets on branches with slashes".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: refstags v3.14.1. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

In the GitHub issue gh:argoproj/argo-cd#15427 (https://github.com/argoproj/argo-cd/issues/15427), the problem reported was: Issue argoproj/argo-cd#15427 (closed, 49 comments): GitHub webhooks stop refreshing ApplicationSets when the tracked branch or tag contains a slash, e.g. env/dev. Pushes to main refresh fine, but pushes to env/dev never trigger a refresh, even though the webhook is delivered. The verified resolution was: Reporter-confirmed root cause and workaround. GitHub sends the full branch ref (refs/heads/env/dev) in the webhook payload, and the ApplicationSet webhook handler misparses refs containing a slash, so the refresh never matches. Maintainer rumstead's workaround, verified by reporter pre: in your git generator, use the fully qualified ref, refs/heads/env/dev for branches or refs/tags/v3.14.1 for tags, instead of the short name. With the qualified ref the webhook matches and refreshes correctly. The underlying parsing bug has a PR upstream, but the qualified-ref form works today.