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fix(auth): cache Clerk JWKS instead of nil-panic on fetch failure#3301

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moshloop merged 1 commit into
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fix/clerk-jwks-nil-panic
Jun 30, 2026
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fix(auth): cache Clerk JWKS instead of nil-panic on fetch failure#3301
moshloop merged 1 commit into
mainfrom
fix/clerk-jwks-nil-panic

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@adityathebe

@adityathebe adityathebe commented Jun 29, 2026 •
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Problem

A transient network blip reaching Clerk's JWKS endpoint (context deadline exceeded fetching .../.well-known/jwks.json) caused a nil-pointer panic in the auth flow, taking down request goroutines and the OIDC callback:

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Configuration used: Organization UI

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Run ID: 54f0ac7b-6ab3-4e34-bf38-7b2fa6993292

📥 Commits

Reviewing files that changed from the base of the PR and between 623d042 and e3432d4.

📒 Files selected for processing (2)
  • auth/clerk_client.go
  • auth/tokens.go

Walkthrough

getJWTKeyFunc in auth/tokens.go is renamed to newClerkKeyfunc and updated to return (jwt.Keyfunc, error) instead of using logger.Fatalf. A new jwksCache struct in auth/clerk_client.go lazily initializes and memoizes the keyfunc using a sync.Mutex, replacing the per-request call pattern in ClerkHandler.

Changes

Lazy JWKS keyfunc caching

Layer / File(s) Summary
newClerkKeyfunc helper
auth/tokens.go		 Renames getJWTKeyFunc to newClerkKeyfunc, changes return type to (jwt.Keyfunc, error), and replaces logger.Fatalf with a wrapped error return on JWKS fetch failure.
jwksCache and ClerkHandler wiring
auth/clerk_client.go		 Adds sync import, introduces jwksCache with mutex-guarded lazy initialization of the keyfunc, and updates NewClerkHandler and parseJWTToken to use h.jwks.keyfunc() instead of calling the helper per request.
🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name Status Explanation Resolution
Docstring Coverage ⚠️ Warning Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Write docstrings for the functions missing them to satisfy the coverage threshold.
✅ Passed checks (4 passed)
Check name Status Explanation
Title check ✅ Passed The title clearly matches the main fix: caching Clerk JWKS and preventing nil-pointer panics on fetch failure.
Linked Issues check ✅ Passed Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check ✅ Passed Check skipped because no linked issues were found for this pull request.
Description Check ✅ Passed Check skipped - CodeRabbit’s high-level summary is enabled.
✨ Finishing Touches
🧪 Generate unit tests (beta)
  • Create PR with unit tests
  • Commit unit tests in branch fix/clerk-jwks-nil-panic
✨ Simplify code
  • Create PR with simplified code
  • Commit simplified code in branch fix/clerk-jwks-nil-panic

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@moshloop moshloop enabled auto-merge (rebase) June 29, 2026 19:24
@adityathebe @moshloop
fix(auth): cache Clerk JWKS instead of nil-panic on fetch failure
e3432d4 
getJWTKeyFunc handled a failed JWKS fetch with logger.Fatalf, but the
slog logger's Fatalf only logs and does not os.Exit. Execution fell
through to `return jwks.Keyfunc` with a nil *keyfunc.JWKS, which later
panicked inside ParseWithClaims -> (*JWKS).getKey on a nil receiver.
So a transient network blip to Clerk crashed request goroutines and the
OIDC callback.

It was also called from parseJWTToken on every Clerk-authenticated
request, so each request did a synchronous JWKS HTTP fetch and spawned a
background-refresh goroutine that lived forever (per-request fetch +
goroutine leak).

Build the JWKS once and reuse it via a pointer-held jwksCache (shared
across ClerkHandler value-receiver copies). Failed fetches are not
cached, so a transient outage retries on the next request instead of
poisoning the handler, and degrades to the existing logged-error/401
path instead of panicking. Key rotation is still handled by keyfunc's
RefreshUnknownKID + hourly refresh against the single long-lived
instance.
@moshloop moshloop force-pushed the fix/clerk-jwks-nil-panic branch from 623d042 to e3432d4 Compare June 30, 2026 06:26
@moshloop moshloop merged commit 7afa082 into main Jun 30, 2026
12 of 13 checks passed
@moshloop moshloop deleted the fix/clerk-jwks-nil-panic branch June 30, 2026 09:14
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2 participants

@adityathebe @moshloop