Cache-Control: no-transform

[ehmicky]

Is your feature request related to a problem? Please describe.
In @middy/http-content-encoding, if the Cache-Control: no-transform request header is set, the response should not be compressed.

Additional context
The standard.
Implementations in Cloudflare and Express.

[willfarrell]

I added in a little more. if the header exists in the request it will add to the response if the header isn't already set. then check if the response has the header set as expected before existing out early

[ehmicky]

Thanks!

Please note the current implementation does not work when the Cache-Control header contains several directives.

If the Cache-Control header in the request is no-transform, no-cache, the following condition will fail.

middy/packages/http-content-encoding/index.js

Line 50 in eaa4f21

if (eventCacheControl === 'no-transform') {

Also, if the Cache-Control header in the response is already set, for example to no-cache, the following line will be ignored, instead of appending it as no-cache, no-transform.

middy/packages/http-content-encoding/index.js

Line 51 in eaa4f21

response.headers['Cache-Control'] ??= 'no-transform'

[willfarrell]

Good catch! A task for tomorrow :).