* Add hwmon support (mainly known from lm-sensors)
This commit adds initial support for linux hardware sensors, exported
through sysfs.
Details of the interface can be found at
https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface
* Add end-to-end test with some real life data
* Cleanup comments on hwmon collector
* Drop raw sensor name from hwmon output
* Let the sensor label be "sensor"
* Add hwmon short description to README.
The convention of the linux driver is nvme($device)n($namespace)p($partition). On *bsd it seems to be different, using "ns" instead of "n" as the namespace separator.
Previously the raw time difference was used which includes the network trip time
between the node and the ntp server. This makes setting alerts off the value
troublesome as it depends on the latency as well as the clock offset.
logind provides a nice interface to find out about the numbers of sessions
on a system; it is used on most Linux distributions, even those which
aren't using systemd.
The exporter exposes the total number of sessions indexed by the following
attributes:
* seat
* type ("tty", "x11", ...)
* class ("user", "greeter", ...)
* remote ("true"/"false")
This removes the requirement to run `node_exporter` as root or with read
access to `/dev/kmem` in order to get CPU usage statistics.
Once FreeBSD adds a macro for the `kern.cp_times` sysctl, the
`setupSysctlMIBs()` function should be replaced by usage of the macro.
When compiling `20ecedd0b4c983bd7b88f97cd7a21461988a6c12` with GNU make (`gmake`) on FreeBSD 10.2-RELEASE, I get the following error:
```
collector/filesystem_bsd.go:60: non-bool mnt[i].f_flags & MNT_RDONLY (type C.uint64_t) used as if condition
Makefile.COMMON:85: recipe for target 'node_exporter' failed
gmake: *** [node_exporter] Error 2
```
This problem is fixed by this patch.
Rene Treffer