Non-Cached Data Being Served as Cached Data in Front Door

The behavior you're observing with Front Door caching content that you've explicitly set to "cache-control: no-cache" is unexpected and could be due to various factors. While there aren't known issues specifically related to the propagation of changes from API Management to Front Door, there are several potential reasons for this behavior and some mitigations you can consider:

Propagation Delay: Even though you made changes to the cache-control headers in API Management, there can be some delay in the propagation of these changes to all Front Door instances or edge nodes. CDNs like Azure Front Door have distributed points of presence (PoPs), and it may take some time for the updated configurations to propagate to all of them.

• Mitigation: Allow some time for the changes to propagate. This can sometimes take several minutes to an hour or more, depending on the CDN and its configuration.

Cache Invalidation: Even with "no-cache" directives, CDNs may still serve cached content until the cache is invalidated or expired. This could be due to the CDN not immediately honoring the "no-cache" directive.

• Mitigation: To ensure that content is not cached, you can implement cache invalidation mechanisms. In Azure Front Door, you can use the "Purge" operation to force cache invalidation for specific URLs or content.

Front Door Configuration: There could be an issue with the Front Door configuration that is causing it to cache content when it shouldn't. Make sure that your Front Door configuration is correctly set up to respect cache-control headers from the API Management service.

• Mitigation: Double-check your Front Door configuration and verify that caching settings are correctly configured to honor cache-control headers. Ensure that there are no conflicting rules or policies.

HTTP Headers: Verify that the "cache-control" headers are being correctly set in the responses from your API Management service. Ensure that there are no intermediary components (such as Azure Application Gateway or other proxies) modifying these headers.

• Mitigation: Review the response headers generated by your API Management service and make sure they include the "cache-control" directives as intended.

Debugging and Monitoring: Utilize logging and monitoring tools to track the behavior of your API Management service and Azure Front Door. Look for any anomalies or unexpected behavior in the logs.

• Mitigation: Use Azure Monitor or other monitoring tools to track the request/response headers and cache behavior. This can help you identify any issues in real-time.

Azure Support: If the issue persists and you can't identify the root cause, consider reaching out to Azure support for assistance. They can provide in-depth investigation and troubleshooting.

It's important to thoroughly investigate and test your configuration and monitoring setup to ensure that cache-control directives are being honored correctly. Depending on your specific use case and configuration, you may need to implement additional mechanisms to ensure that content is not cached when it shouldn't be.

@Glenn Darrin

May I know if you got a chance to review my previous comment?

Please let me know if you are facing any challenges or if there are any follow-up questions, I shall be glad to address them.

Thanks,

Kapil

@Glenn Darrin

Can you please update us if the action plan provided was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.

Thanks,

Kapil