Retry ALB CreateRule on PriorityInUse race condition

[Copilot]

Concurrent Lambda invocations for different ACME domains each call GetNextAvailablePriority independently, causing both to claim the same priority. The second CreateRule call fails with PriorityInUse.

Changes

• aws/alb/updatealb.go: Added createRuleWithRetry — on PriorityInUse, waits 1s, re-fetches the next available priority (which now correctly skips the priority claimed by the competing invocation), and retries up to 10 times
• Refactored AddListenerStaticRule and AddListenerTriggerTargetGroupRule to use createRuleWithRetry

func createRuleWithRetry(ctx context.Context, svc *elbv2.Client, listenerArn string, input *elbv2.CreateRuleInput) error {
    for i := 0; ; i++ {
        if _, err := svc.CreateRule(ctx, input); err != nil {
            var apiErr smithy.APIError
            if errors.As(err, &apiErr) && apiErr.ErrorCode() == "PriorityInUse" {
                if i >= maxPriorityRetries {
                    return fmt.Errorf("failed to create rule after %d retries: %w", maxPriorityRetries, err)
                }
                log.Printf("Priority %d is in use, retrying (%d/%d)...", *input.Priority, i+1, maxPriorityRetries)
                time.Sleep(time.Second)
                priority, err := GetNextAvailablePriority(ctx, listenerArn)
                // ...
                input.Priority = ptr.Int32(priority)
                continue
            }
            return err
        }
        return nil
    }
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Race: multiple lambda invocations try to create rule with priority 1</issue_title>
<issue_description>Two ACME domains result in two separate lambda invocations (until we do #5), each creating a rule starting from priority 1, causing one lambda to fail. We could handle the priority failure and retry.

2026-03-16T21:13:25.506Z cd ** error: sdk-v2/provider2.go:572: sdk.helper_schema: invoking Lambda Function (acme-lambda-0d3a9fa): {"errorMessage":"failed to create listener static rule: operation error Elastic Load Balancing v2: CreateRule, https response error StatusCode: 400, RequestID: 24b62462-04f5-4e6b-ba9c-f954daf18fdd, PriorityInUse: Priority '1' is currently in use","errorType":"wrapError"}: provider=aws@6.83.2

Workaround: rerunning the deployment should fix it.
</issue_description>

<agent_instructions>Handle the PriorityInUse error message and retry creation of ListenerRule</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Race: multiple lambda invocations try to create rule with priority 1 #6

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