Summary

Connection limiter returns HTTP 429 when Redis unavailable, blocking all proxy cache requests.

Expected Behaviour

Redis failures handled gracefully:

• Allow request to proceed when Redis down (fail open), or
• Return 503 Service Unavailable instead of 429, or
• Log error and continue without rate limiting

Actual Behaviour

src/server/middleware/repoproxy/proxy.go:114 and :258

Treats any Acquire() failure as rate limit exceeded:

if !connection.Limiter.Acquire(ctx, client, key, p.MaxUpstreamConnection()) {
    log.Infof("current connection exceed max connections to upstream registry")
    return tooManyRequestsError  // returns 429
}

When Redis unavailable, all proxy cache pulls fail with 429 even though no limit was exceeded. Should differentiate between "limit exceeded" and "Redis error".