Скачать или смотреть Resolving java.net.UnknownHostException While Connecting Eureka and Zuul in Microservices

Learn how to troubleshoot the error `java.net.UnknownHostException: eureka-service` when connecting Eureka and Zuul in your microservices architecture.
---
This video is based on the question https://stackoverflow.com/q/63204811/ asked by the user 'Avartiai' ( https://stackoverflow.com/u/9484759/ ) and on the answer https://stackoverflow.com/a/63205426/ provided by the user 'adarsh' ( https://stackoverflow.com/u/8746228/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Trying to connect Eureka and Zuul and I have error

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting Connection Errors in Microservices: Eureka and Zuul

In the world of microservices architecture, service discovery and routing are essential components. Services like Eureka and Zuul from Netflix assist in these areas. However, developers might encounter connection issues when integrating these services, such as the error java.net.UnknownHostException: eureka-service. In this guide, we'll explore what this error means and how to resolve it effectively.

Understanding the Problem

When you're trying to connect your Zuul service to your Eureka service, you might see an error indicating that the host eureka-service cannot be resolved. This issue arises from the configuration in your Zuul application that references the Eureka service using a hostname instead of an IP address.

What Causes the Error?

The root cause of the UnknownHostException usually stems from the following:

Eureka Service Hostname: The Zuul service is trying to connect to eureka-service. This is a hostname that isn’t recognized by the system or the network.

Here's the relevant line from the application.properties of your Zuul service that causes the issue:

[[See Video to Reveal this Text or Code Snippet]]

In many environments, especially during local testing, the hostname eureka-service may not be defined, leading to the connection failure.

Solution Steps

Step 1: Use the Correct Hostname or IP Address

To resolve the UnknownHostException, you need to replace eureka-service with the IP address or the correct hostname where your Eureka service is running. Here’s how you can do that:

If your Eureka service is running locally (on the same machine), simply use localhost as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Validate Your Configuration

Eureka Application Properties: Ensure that your Eureka service application.properties is correctly configured and that it’s running on port 9000:

[[See Video to Reveal this Text or Code Snippet]]

Zuul Application Properties: After changing the eureka.client.service-url.defaultZone, your Zuul service configuration should look like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Restart Your Services

After making the necessary changes to the configuration files, restart both your Eureka and Zuul services. This ensures that the new configurations are loaded properly.

Step 4: Test the Connection

Once both services are restarted, you can verify that Zuul can successfully connect to Eureka. Check the logs of your Zuul service for any errors. If everything is configured correctly, the error should no longer appear.

Conclusion

Integrating Eureka and Zuul in your microservices architecture is a powerful way to manage service discovery and routing. However, issues like the UnknownHostException can hinder your progress. By ensuring you’re using the correct hostname or IP address, you can resolve such errors quickly.

For further help with microservices in Docker, feel free to drop your questions in the comments section below!