Cache Control headers not set when cacheControl extension is enabled

[blimmer]

Package Name & Version

The issue is present in apollo-server-express, the latest version (2.6.4).

Latest version where the problem did not occur

I believe this issue was introduced with this commit, where a test was added explicitly for this behavior.

Expected Behavior

When the cacheControl extension is enabled, the server should continue sending Cache-Control HTTP headers.

Actual Behavior

When the cacheControl extension is enabled, the server no longer sends Cache-Control HTTP headers.

Repo demonstrating the problem

https://github.com/blimmer/apollo-server-express-bug-report

[blimmer]

This issue is a result my PR attempting to document this behavior (#2880) where @abernix recommended opening an issue.

[glasser]

The cacheControl option for configuring cache control was removed from Apollo Server in v3 last year. (The feature still exists but is implemented as a standard Apollo Server plugin.)

My memory is that cacheControl: true was a weird backwards-compatible thing that added a GraphQL extension to the response (used by the engineproxy project which was discontinued in 2018) and did not set cache-control headers, so the bug reported here was "working as intended" but not a useful feature, and this legacy support is no longer part of Apollo Server.