Troubleshooting Azure Event Grid: Event delivery failures and misconfigurations

Azure Event Grid is a powerful tool for building scalable, event-driven architecture. It provides a centralized event-routing system to manage events from multiple components. You can use it to easily build reactive applications that can respond to events in almost real time.

However, Event Grid can cause errors within your architecture. Misconfigurations and event delivery errors in your setup can significantly impact your application’s overall performance and reliability. These issues are challenging to resolve, leading to additional work and delays in development. Fortunately, implementing efficient troubleshooting and preventive practices can help you ensure a robust and performant event-driven infrastructure.

This article will help you troubleshoot common issues with your Event Grid setup, including failures and misconfigurations with event publishers, subscribers, and event delivery. You’ll also learn some best practices to employ more consistent and effective troubleshooting.

Solving Azure Event Grid failures and misconfigurations

Monitoring Event Grid’s performance is crucial for detecting e service disruptions or downtime, latency, and potential security risks. For example, an unusually large number of events sent to your Event Grid topic could indicate a poor client configuration or potential security threat, such as a distributed denial-of-service (DDoS) attack.

Microsoft Azure provides various tools to help you monitor and diagnose such issues within your environments. Using these tools helps maximize your application’s availability, reliability, and performance.

Event Grid Metrics is Event Grid’s built-in monitoring feature. It provides logs and metrics that allow you to track the number of sent and received events as well as rates of latency, delivery, and errors.

You can also use Site24x7 to monitor your Azure resources, a unified solution that collects telemetry data from various sources across Azure and on-premises environments. It then displays that data in a centralized dashboard so you can easily view and analyze performance metrics, logs, and alerts. Key metrics that will let you know there are issues related to Azure Event Grid include:

• DeliveryAttemptFailCount
• PublishFailCount
• DeliveryAttemptFailCount
• PublishFailCount
• FailedPublishedEvents
• FailedReceivedEvents
• FailedReleasedEvents
• FailedPublishedMessages
• PublishFailCount

One of Site24x7's most powerful tools is APM. While Site24x7 Azure Monitoring focuses on infrastructure and resources, application performance monitoring (APM), provides detailed insights into your app’s performance and user behavior throughout all stages of development.

Common issues with event publishers

Event publishers often encounter issues that can impact the reliability and accuracy of event data. These issues can include authentication errors, rate limiting, and incorrect event schemas.

Authentication errors

Authentication errors occur when the event publisher isn’t authorized to send data to the event collection system. Unauthorized access attempts can result from invalid credentials, expired tokens, or misconfigured access controls. In the Azure Portal logs, you can check for messages that indicate:

• Authentication Errors
• Authorization Errors
• Token Validation Failures
• Invalid Signatures
• Token Expiration Errors

There are several best practices to mitigate authentication errors:

• Ensure you have the correct authentication credentials and permissions.
• Double-check the API key or access token and confirm you have the required privileges to write to the event collection system.
• Verify that your authentication token has not expired. Many authentication tokens have a limited lifespan, so refresh them periodically.
• Implement secure communication protocols, including HTTPS and TLS, to prevent unauthorized access and data interception.
• Review authentication logs regularly to detect and respond to unauthorized access attempts.

Rate limiting errors

Rate limiting errors occur when the event publisher exceeds the maximum event rate that the event collection system can handle. This type of error will result in dropped events, delayed processing times, and degraded performance. There may be rate limiting errors if the logs contain:

• HTTP 429 Response Codes
• Backoff Durations
• Event Delivery Latencies

Some best practices to address rate limiting errors include the following:

• Implement retries with exponential backoff to allow the system time to recover and handle incoming events more effectively.
• Implement batching and compression techniques to reduce the number of sent requests.
• Monitor system performance and adjust the rate limit based on system capacity.
• Use a load balancer to distribute event traffic and prevent overload on individual systems.

Incorrect event schemas

Incorrect event schemas occur when the publisher sends event data that doesn’t conform to the expected data model. This occurrence can result in data loss or errors in downstream processing. To help you identify the presence of incorrect schemas, check your logs for messages suggesting:

• Invalid Event Payloads
• Event Schema Mismatches
• Event Validation Errors

Here are some best practices to prevent incorrect event schemas:

• Define and adhere to a standard event schema.
• Use data validation techniques to ensure the event data conforms to the defined schema.
• Provide clear documentation and error messages to help publishers identify and correct schema issues.
• Implement automated testing and monitoring to detect schema issues before they impact downstream systems.

Common issues with event subscribers

Event subscribers can also encounter issues that impact their ability to receive and process events, including webhook configuration errors and handling event validation codes.

Webhook configuration errors

Webhook configuration errors occur when the subscriber’s webhook URL is incorrect or misconfigured, preventing events from reaching their intended endpoint. When checking for webhook configuration errors in Azure logs, be sure to check messages containing:

• Non-200 level HTTP status codes
• Delivery Timeouts
• Delivery Retry attempts

Best practices to address webhook configuration errors:

• Ensure the webhook URL is correct and points to the intended endpoint.
• Confirm that the subscriber’s server is internet-accessible and that the ports are open to receive incoming traffic.
• Implement a webhook testing tool or use a third-party testing service to confirm that the subscriber can receive and process events successfully.

Handling event validation codes

Handling event validation codes ensures that the subscriber will only process valid events. These codes are typically included in the event payload and used to verify the authenticity of the event source. You may want to check your logs for event validation error messages.

Below are some best practices to address event validation code issues:

• Verify the event validation code to ensure that it matches the expected value. You can verify the event signature with a shared secret or cryptographic key.
• Implement event filtering to avoid processing events from unauthorized sources.
• Monitor event validation logs to detect and respond to suspicious or unauthorized activity.
• Implement rate limiting or throttling techniques to prevent overload and ensure timely event processing.

Common event delivery issues

Event delivery issues can occur when events aren’t delivered to the intended endpoint for processing and analysis. These issues can include network errors, resource throttling, and event filtering misconfigurations.

Network errors

Network errors can occur when the connection between the event publisher and the subscriber is disrupted or unstable. Such errors might result in dropped events, delayed processing times, and degraded performance. Check for log messages indicating prolonged network latencies, connection timeouts, DNS Resolution, and delivery retries.

Best practices to resolve network issues include the following:

• Use a reliable network protocol like TCP to ensure secure and reliable event transmission.
• Implement retries with exponential backoff to ensure the events retransmit if their initial delivery attempts are unsuccessful.
• Monitor network performance regularly to detect and respond to any network issues that may impact event delivery.

Resource throttling

Resource throttling occurs when the event collection system or subscriber limits the amount of data it can send or process, resulting in dropped events or processing delays. Your logs may indicate that your subscription has exceeded its Resource Quotas and Limits.

Best practices to manage resource throttling include the following:

• Implement batching and compression techniques to reduce the amount of data that needs to be transmitted and processed.
• Monitor system performance and adjust event sending and processing rates based on system capacity.
• Consider using a load balancer or other distributed systems to manage event traffic and prevent overload on individual systems.

Event filtering misconfigurations

Event filtering misconfigurations can occur when the subscriber misconfigures the event filtering rules, preventing events from being routed to the intended endpoint.

Best practices to resolve event filtering misconfigurations include the following:

• Regularly review and update event filtering rules to ensure accuracy and relevance.
• Provide clear documentation and error messages to help subscribers identify and correct event filtering misconfigurations.
• Implement automated testing and monitoring to detect misconfigurations before they impact downstream systems.
• Consider using a dedicated event routing tool or service to simplify event routing and ensure reliable delivery.

Conclusion

Azure Event Grid is essential for creating a robust event-driven architecture. However, to make the most of its services, you must be able to prevent or mitigate any potential issues. Errors with your event subscribers, publishers, or event delivery can cause significant problems, especially as your application grows in complexity.

You can quickly troubleshoot and avoid these errors by following the right strategies and best practices. Azure also provides various tools to help you monitor your application’s performance and detect potential issues early on.