Add Cache-Control header to static resources to help caching

[nzmsv]

Changes

Prior to this change putting the dashboard behind ALB broke static resource caching. ALB seems to remove the Date header from the response it proxies, however it will obey explicit Cache-Control headers.

Static resources coming from webpack already have a content hash as part of their name so they are already immutable.

Note: the first draft of this PR used the Etag header instead. See the discussion below.

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[tekton-robot]

Hi @nzmsv. Thanks for your PR.

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[a-roberts]

/ok-to-test
@AlanGreene FYI

[a-roberts]

/test tekton-dashboard-unit-tests

[AlanGreene]

@nzmsv thanks for the PR, adding caching support would be very useful for a lot of use cases.

Since the URLs for the static resources already contain a content-based hash we know that content can be cached long-term without requiring periodic revalidation as in the case of using entity tags or similar approaches. Instead of sending the Etag header in the response, we could set a long max-age on the Cache-Control header and eliminate the conditional requests from the browser.

Something like Cache-Control: public, max-age=31536000, immutable

Would this work for your use case?

[nzmsv]

@nzmsv thanks for the PR, adding caching support would be very useful for a lot of use cases.

Since the URLs for the static resources already contain a content-based hash we know that content can be cached long-term without requiring periodic revalidation as in the case of using entity tags or similar approaches. Instead of sending the Etag header in the response, we could set a long max-age on the Cache-Control header and eliminate the conditional requests from the browser.

Something like Cache-Control: public, max-age=31536000, immutable

Would this work for your use case?

Thanks, this is a great idea! I tested the Cache-Control header behind ALB and it works correctly. I updated the PR accordingly.

[AlanGreene]

/test tekton-dashboard-unit-tests

[AlanGreene]

/lgtm
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[AlanGreene]

/test tekton-dashboard-unit-tests