Instead of maintaining a counter metric for device errors in memory,
this change exports a gauge and uses const metrics to avoid leaking
metrics for unmounted filesystems.
Named return variables should only be used to describe the returned type
further, e.g. `err error` doesn't add any new information and is just
stutter.
node_exporter currently triggers autofs to mount the underlying
filesystem on every scrape. This is undesirable. Better ignore autofs.
The underlying filesystem that autofs mounts will be monitored though,
when the (real) filesystem is mounted.
Current behaviour throws away all stats on any Statfs error. In practice
this is not useful. This turns such errors into debug log messages -
though silently ignoring them seems even more valid to me.
Remove all hardcoded references to `/proc`. For all collectors that do
not use `github.com/prometheus/procfs` yet, provide a wrapper to
generate the full paths.
Reformulate help strings, errors and comments to remove absolute
references to `/proc`.
This is a breaking change: the `-collector.ipvs.procfs` flag is removed
in favor of the general flag. Since it only affected that collector it
was only useful for development, so this should not cause many issues.
