Скачать или смотреть Troubleshooting 404 Errors in Istio: A Guide to URL Regex Match for VirtualService

Discover how to resolve `404 errors` in Istio when using URL regex matches in VirtualService for your Kubernetes Gateway.
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This video is based on the question https://stackoverflow.com/q/63102235/ asked by the user 'Jim' ( https://stackoverflow.com/u/3715861/ ) and on the answer https://stackoverflow.com/a/63104683/ provided by the user 'Jim' ( https://stackoverflow.com/u/3715861/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting 404 Errors in Istio: A Guide to URL Regex Match for VirtualService

When working with Istio in a Kubernetes setup, you may encounter unexpected HTTP 404 errors when trying to access specific routes configured in your VirtualService. In this guide, we'll explore a common scenario where a gateway and a virtual service are configured but lead to a 404 response. We’ll identify the potential issue and provide a clear solution to ensure your routes work correctly.

Understanding the Problem

A user recently configured a Gateway and a VirtualService for a sample BookInfo application. The user expected it to route requests as defined but received a 404 error when trying to access an endpoint.

The configuration looks a little something like this:

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

The corresponding VirtualService is configured to match a specific URI:

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

When attempting to access http://External-IP/api/v1/products, the request failed with a 404 error, indicating that the routing was not correctly configured to match the URI.

Identifying the Issue

The root of the problem lies in the misunderstandings regarding how regex patterns work in the Istio configuration:

The original regex pattern v1 used in the match configuration does not perform a partial match. Instead, it only matches the exact string v1 and would not consider the URI api/v1/products.

Solution

To resolve the 404 error, you need to adjust the regex pattern for more flexible matching. The correct approach would be to utilize a regex that captures any occurrences of v1 within a broader range of URIs.

Revised Regex Configuration

Change the regex pattern in your VirtualService configuration from:

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

To:

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

This adjustment allows the routing to identify any URLs that contain v1 anywhere in the path, including your target endpoint /api/v1/products.

Finalized Example Configuration

Here’s how your updated VirtualService configuration should look:

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

Conclusion

By updating the regex pattern to .*v1.*, you're able to allow for more flexible URL handling within your Istio VirtualService. This small change can make a significant difference in routing your requests correctly and eliminating unwanted 404 errors.

If you're encountering similar issues or have questions, feel free to leave a comment below. Happy coding!