Adjust imgsrv metrics

[aelkiss]

Partially reverts #13

• Use /ram/imgsrv-metrics for a consistent location for shared location for updating metrics (/tmp in Debian 13 is too transient and has caused issues)

• Remove Utils::MonitorRun -- this was pretty hacky and we haven't ended up using the metrics from it.

If this continues to cause issues, we may want to back off on metrics here entirely and instead analyze metrics from the logs until we have a better sense of what to record & a stable way to record it.

[aelkiss]

I'll want to verify this works as expected in dev before merging it. I'm not sure what the interaction will be between the persistent PSGI imgsrv and other things that might try to update the stats, and I don't remember how exactly this was working before.

If we can't get it working reliably, we can just turn it off.

[aelkiss]

Probably not super urgent as @rrotter has put another fix in place to avoid the Debian 13 behavior of trying to automatically clean out old stuff in /tmp

[moseshll]

Is "yes" saying "no" to unzip? I haven't ventured much into this corner of imgsrv, so it raises the question for me, what question is unzip prompting us to answer? And what is the resulting behavior when we say "n" to whatever question this is? (I realize the handling of the unzip call is peripheral to what we're really doing here, but since we're here...)

[aelkiss]

That's a good question...

[moseshll]

See comment-in-passing. Nothing here fills me with dread. APPROVE

[rrotter]

Continuing to use /ram is a bit redundant, since /tmp is also tmpfs:

# df -h /ram /tmp
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           4.0G  1.4G  2.7G  35% /ram
tmpfs            18G  2.0M   18G   1% /tmp

I'd like /tmp to be usable, and not something we avoid because of systemd weirdness, and personally I'd work towards deprecating /ram. Up to you of course, just my $0.02.

[aelkiss]

Continuing to use /ram is a bit redundant, since /tmp is also tmpfs:

# df -h /ram /tmp
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           4.0G  1.4G  2.7G  35% /ram
tmpfs            18G  2.0M   18G   1% /tmp

I'd like /tmp to be usable, and not something we avoid because of systemd weirdness, and personally I'd work towards deprecating /ram. Up to you of course, just my $0.02.

Since imgsrv is already using /ram quite extensively, having it all be in the same place for the time being makes sense to me, BUT in the future we could definitely try to get rid of /ram.