install-a-squid-server: After following the instructions the service barely caches anything

[brlin-tw]

There are a few problems that will confuse readers, that the proxy not working as expected:

• The object cache size limit in the default configuration may be too small for most objects to be cached:

  • max_object_size
  • max_object_size_in_memory

• The default refresh_patterns don't cache generic filetypes(png|jpg|zip|tar*|...):

    > refresh_pattern ^ftp:           1440    20%     10080
    > refresh_pattern -i (/cgi-bin/|\?) 0     0%      0
    > refresh_pattern \/(Packages|Sources)(|\.bz2|\.gz|\.xz)$ 0 0% 0 refresh-ims
    > refresh_pattern \/Release(|\.gpg)$ 0 0% 0 refresh-ims
    > refresh_pattern \/InRelease$ 0 0% 0 refresh-ims
    > refresh_pattern \/(Translation-.*)(|\.bz2|\.gz|\.xz)$ 0 0% 0 refresh-im
    > #refresh_pattern (\.deb|\.udeb)$   129600 100% 129600
    > refresh_pattern .              0       20%     4320
  

• The default squid configuration doesn't cache HTTPS requests(needs an MITM configuration for that to work)

We should at least mention these potential cases, and provide instructions for readers to verify whether the cache has hit or not(e.g., via certain fields of the access log).

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Document: how-to/web-services/install-a-squid-server.md

[panlinux]

https://documentation.ubuntu.com/server/how-to/web-services/install-a-squid-server/

Very good suggestions, thanks.