Webhook Retries: Best Practices for Reliable Communication

When a webhook call fails, the sending application needs to decide whether to try again. Without a retry strategy, you risk losing critical data. For example, if a payment gateway fails to notify your e-commerce store about a successful transaction, you might not fulfill the order, leading to a poor customer experience.

A well-implemented retry strategy increases the reliability of your webhooks, making your application more resilient to temporary failures.

When a webhook fails, you shouldn't immediately retry. If the receiving server is down, bombarding it with requests will only make things worse. Instead, use an exponential backoff strategy.

Exponential backoff involves increasing the delay between retries exponentially. For example, you might wait 2 seconds before the first retry, 4 seconds before the second, 8 seconds before the third, and so on. This gives the receiving server time to recover.

const waitTime = initialDelay * Math.pow(2, retryCount);

If many webhooks fail at the same time, an exponential backoff strategy could lead to a "thundering herd" problem, where all the retries happen at the same time. To avoid this, add a small, random delay to each retry. This is known as jitter.

const jitter = Math.random() * 1000; // random delay up to 1 second
const waitTime = initialDelay * Math.pow(2, retryCount) + jitter;

While retries are useful for transient failures, they can't solve permanent problems. If a webhook continues to fail after several retries, it's likely that there's a more serious issue.

Set a maximum number of retries to avoid wasting resources on a failing endpoint. After the maximum number of retries is reached, you should log the failure and move the webhook to a dead-letter queue for manual inspection.

Detailed logging is crucial for debugging webhook failures. For each retry attempt, you should log:

• The timestamp of the attempt.
• The HTTP status code of the response.
• The response body, if any.

Monitoring your webhook failure rate can help you detect problems before they impact your users. Set up alerts to notify you when the failure rate exceeds a certain threshold.

Sometimes, you might successfully process a webhook but fail to send a success response to the sender. This can cause the sender to retry the webhook, leading to duplicate processing.

To prevent this, your webhook handler should be idempotent. This means that processing the same webhook multiple times has the same effect as processing it once. You can achieve idempotency by checking for a unique identifier in the webhook payload before processing it.