make static cache policy explicit, disable caching for objects >100 MiB

[syphar]

When trying to download bigger archives, I saw some errors:

curl: (92) HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR (err 1)

or

http: error: ChunkedEncodingError: ("Connection broken: InvalidChunkLength(got length b'\r\n', 0 bytes read)", InvalidChunkLength(got length b'\r\n', 0 bytes read))

After a little digging I saw that the connection between fastly & nginx is cut after streaming exactly 100 MiB,

which made me think about limits :)

Then :

• https://docs.fastly.com/products/compute-resource-limits#default-limits
• https://www.fastly.com/documentation/guides/full-site-delivery/performance/failure-modes-with-large-objects/
• https://www.fastly.com/documentation/guides/full-site-delivery/caching/segmented-caching/

For now I chose to just forbid caching when the file is too big, segmented caching would be a little more effort, with IMO limited short-term gain. These archives aren't downloaded that often.

[marcoieni]

looks good!