Make cvmfs_http_proxy default to DIRECT

[DrDaveD]

Since github actions are run in Azure where there is not normally a proxy defined, leaving cvmfs_http_proxy unset results in a call to WLCG Web Proxy Auto Discovery (WPAD). If there are enough of them in a short period of time (125 requests within 15 minutes) from the one organization (as defined by Maxmind) then the WPAD directs clients to backup proxies, which causes an alarm. That alarm was triggered yesterday. This PR fixes that problem by defaulting cvmfs_http_proxy to DIRECT.

After merging I would like a new tag, and I will also backport to v4 where we'll need another tag. The specific action that likely triggered the alarm was using v4.

[wdconinc]

I'm wondering, is this not shifting the burst of activity from a WPAD and the backup proxies to the primary server? Should we instead ensure that a proxy server is set in these actions so WPAD doesn't need to be contacted?

Also, possibly useful to alert the downstream workflow and encourage them to upgrade.

[DrDaveD]

I'm wondering, is this not shifting the burst of activity from a WPAD and the backup proxies to the primary server? Should we instead ensure that a proxy server is set in these actions so WPAD doesn't need to be contacted?

Setting it to DIRECT is the right thing to do, because cvmfs_use_cdn is already defaulted to yes; all the requests will go to Cloudflare, which is what we want for this case. That's better then sending them to some random squid, unless we could run one in Azure itself and make it publicly available to all clients running in Azure.

Also, possibly useful to alert the downstream workflow and encourage them to upgrade.

That would be easy enough for this case but I don't know how many other users there may be or how to contact them.

[wdconinc]

Thanks for the additional detail. Sounds like this is fine to merge then. The squid on azure can be for future consideration.

Also, possibly useful to alert the downstream workflow and encourage them to upgrade.

That would be easy enough for this case but I don't know how many other users there may be or how to contact them.

Yeah, that doesn't scale well. If it ever is useful, https://github.com/cvmfs-contrib/github-action-cvmfs/network/dependents has a full list of users of the action (but not the version).