Traefik 502 Bad Gateway

Traefik is unable to connect to the backend service.

Understanding Traefik

Traefik is a modern HTTP reverse proxy and load balancer that makes deploying microservices easy. It is designed to integrate with your existing infrastructure components and provides dynamic configuration capabilities. Traefik is widely used for routing traffic to various backend services, making it a popular choice for cloud-native applications.

Identifying the Symptom: 502 Bad Gateway

When using Traefik, encountering a 502 Bad Gateway error indicates that Traefik is unable to successfully connect to the backend service. This error is typically observed when a request is made, and Traefik cannot establish a connection to the intended service, resulting in an unsuccessful response.

Understanding the 502 Bad Gateway Error

The 502 Bad Gateway error is an HTTP status code that signifies a communication problem between the proxy server (Traefik) and the backend server. This error can occur due to various reasons, such as the backend service being down, network issues, or misconfigurations in the Traefik setup.

Common Causes of 502 Errors

The backend service is not running or has crashed.
Network connectivity issues between Traefik and the backend.
Incorrect configuration in Traefik's routing rules.

Steps to Resolve the 502 Bad Gateway Error

To resolve the 502 Bad Gateway error, follow these steps:

Step 1: Verify Backend Service Status

Ensure that the backend service is running and accessible. You can check the status of the service using the following command:

systemctl status your-backend-service

If the service is not running, start it with:

systemctl start your-backend-service

Step 2: Check Network Connectivity

Ensure that Traefik can reach the backend service. Use tools like curl or ping to test connectivity:

curl http://backend-service-url

If there are connectivity issues, check your network settings and firewall rules.

Step 3: Review Traefik Configuration

Inspect Traefik's configuration files to ensure that the routing rules are correctly set up. Verify that the service URL and port are correctly specified in the configuration. For more information on configuring Traefik, refer to the Traefik Documentation.

Step 4: Check Logs for Errors

Examine Traefik's logs for any error messages that might provide additional insights. Use the following command to view logs:

docker logs traefik-container-name

Look for any error messages related to connectivity or configuration issues.

Conclusion

By following these steps, you should be able to diagnose and resolve the 502 Bad Gateway error in Traefik. Ensuring that your backend services are running and properly configured is crucial for maintaining a healthy microservices environment. For further reading, visit the official Traefik documentation.

Traefik

Cheatsheet

(Perfect for DevOps & SREs)

Most-used commands

Thankyou for your submission

We have sent the cheatsheet on your email!

Oops! Something went wrong while submitting the form.

MORE ISSUES

Traefik Traefik not respecting authentication rules

Authentication rules are not being applied.

Traefik Traefik not respecting authorization rules

Authorization rules are not being applied.

Traefik Traefik not respecting security rules

Security rules are not being applied.

Traefik Traefik not respecting plugin rules

Plugin rules are not being applied.

Traefik Traefik not respecting middleware rules

Middleware rules are not being applied.

Traefik Traefik not respecting custom rules

Custom routing rules are not being applied.

Traefik Traefik not respecting regex rules

Regex-based routing rules are not being applied.

Traefik Traefik not respecting query rules

Query parameter-based routing rules are not being applied.

Traefik Traefik not respecting IP rules

IP-based routing rules are not being applied.

Traefik Traefik not respecting SNI rules

SNI-based routing rules are not being applied.

Traefik Traefik not respecting path rules

Path-based routing rules are not being applied.

Traefik Traefik not respecting cookie rules

Cookie-based routing rules are not being applied.

Traefik Traefik not respecting host rules

Host-based routing rules are not being applied.

Traefik Traefik not respecting header rules

Header-based routing rules are not being applied.

Traefik Traefik not respecting method rules

HTTP method-based routing rules are not being applied.

Traefik Traefik not respecting entry points

Entry point configuration is not being applied.

Traefik Traefik not updating configuration

Dynamic configuration changes are not being applied.

Traefik Traefik not respecting priority

Routing priority rules are not being applied.

Traefik Metrics not exposed

Metrics endpoint is not configured or exposed.

Traefik Service weight configuration is not being respected.

Service weight configuration is not being correctly set or applied.

Traefik Traefik high memory usage

Traefik is consuming more memory than expected.

Traefik Traefik high CPU usage

Traefik is under heavy load or misconfigured.

Traefik Traefik logs not available

Logging is not correctly configured.

Traefik UDP routing issues

UDP routes are not correctly configured.

Traefik TCP routing issues

TCP routes are not correctly configured.

Traefik IngressRoute not working

IngressRoute is not correctly configured.

Traefik Sticky sessions not working

Session affinity is not correctly configured.

Traefik Middleware not applied

Middleware rules are not being executed.

Traefik Traefik is unable to discover services.

Service discovery configuration is incorrect or services are not registered.

Traefik Traefik not starting

Configuration errors or missing dependencies.

Traefik Circuit breaker not triggering

Circuit breaker rules are not being applied.

Traefik Header manipulation not applied

Traefik is not applying header rules as expected.

Traefik Rate limiting not enforced

Rate limiting rules are not being applied.

Traefik Path-based routing issues in Traefik.

Incorrect path rules causing routing errors.

Traefik Invalid configuration file

There is a syntax error in the Traefik configuration file.

Traefik DNS resolution failure

Traefik cannot resolve the domain name.

Traefik Health check failures

Backend services are failing health checks.

Traefik Redirect loop

Improper redirection rules causing infinite loops.

Traefik CORS issues

Cross-Origin Resource Sharing (CORS) is not properly configured.

Traefik Traefik dashboard inaccessible

The Traefik dashboard is not exposed or misconfigured.

Traefik Load balancing not working

Traefik is not distributing traffic among backend services.

Traefik Service not registered

The service is not registered with Traefik.

Traefik Backend connection refused

Traefik cannot connect to the backend service.

Traefik Rate limit exceeded

Too many requests are being sent to Let's Encrypt.

Traefik 502 Bad Gateway

Traefik is unable to connect to the backend service.

Traefik ACME certificate renewal failure

Traefik is unable to renew the Let's Encrypt certificate.

Traefik TLS handshake error

There is a problem with the SSL/TLS configuration.

Traefik 503 Service Unavailable

The backend service is overloaded or down.

Traefik 504 Gateway Timeout

The backend service did not respond in a timely manner.

Traefik 404 Not Found

The requested resource could not be found on the server.

Backed by

Resources

Contact

Platform

Connect

Made with ❤️ in & 🏢

Doctor Droid

Join and start debugging.

Log in or create a free account to start debugging your production application