Improve cache times of GCS-hosted images

[stevejalim]

Wagtail stores user media in a GCS bucket, and pages load those assets directly from the bucket.

I've just noticed that the max-age for the Cache-control header is 1hr.

It would be good to increase this. I don't think there's a downside of a high TTL: if someone uploads a file with the same filename, the settings will ensure that the new file has a different filename to an existing one.

[stevejalim]

I think we can do this via settings for django-storages, so no SRE magic needed, but just ccing you @bkochendorfer because I know how much you love cache-control :)

[stevejalim]

Heya @bkochendorfer - here's an interesting (and non-critical) one...

Looking at this, the images in GCS are coning back with cache-control: public, max-age=3600

But in theory when we upload them we are setting:

GS_OBJECT_PARAMETERS = {
    "cache_control": "max-age=2592000, public, immutable",
    # 2592000 == 30 days 1 month age
}

and the cache_control key looks right compared to the docs

Any chance there is something going on at GCS (or at the CDN layer for when the origin is GCS) please?

[bkochendorfer]

Can you provide an example URL for me to investigate?

[stevejalim]

@bkochendorfer D'oh that would have been useful for me to do, yeah.

https://storage.googleapis.com/future-prod-prod-storage/images/ai.original.svg is an example of a GCS-held image where the cache time isn't what we're expecting. No super rush to look at this. Thanks, dude!