telegraf/plugins/inputs/disk/README.md

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# Disk Input Plugin
The disk input plugin gathers metrics about disk usage.
Note that `used_percent` is calculated by doing `used / (used + free)`, _not_
`used / total`, which is how the unix `df` command does it. See
https://en.wikipedia.org/wiki/Df_(Unix) for more details.
### Configuration:
```toml
[[inputs.disk]]
## By default stats will be gathered for all mount points.
## Set mount_points will restrict the stats to only the specified mount points.
# mount_points = ["/"]
## Ignore mount points by filesystem type.
ignore_fs = ["tmpfs", "devtmpfs", "devfs", "overlay", "aufs", "squashfs"]
```
#### Docker container
To monitor the Docker engine host from within a container you will need to
mount the host's filesystem into the container and set the `HOST_PROC`
environment variable to the location of the `/proc` filesystem. If desired, you can
also set the `HOST_MOUNT_PREFIX` environment variable to the prefix containing
the `/proc` directory, when present this variable is stripped from the
reported `path` tag.
```
docker run -v /:/hostfs:ro -e HOST_MOUNT_PREFIX=/hostfs -e HOST_PROC=/hostfs/proc telegraf
```
### Metrics:
- disk
- tags:
- fstype (filesystem type)
- device (device file)
- path (mount point path)
- mode (whether the mount is rw or ro)
- fields:
- free (integer, bytes)
- total (integer, bytes)
- used (integer, bytes)
- used_percent (float, percent)
- inodes_free (integer, files)
- inodes_total (integer, files)
- inodes_used (integer, files)
### Troubleshooting
On Linux, the list of disks is taken from the `/proc/self/mounts` file and a
[statfs] call is made on the second column. If any expected filesystems are
missing ensure that the `telegraf` user can read these files:
```
$ sudo -u telegraf cat /proc/self/mounts | grep sda2
/dev/sda2 /home ext4 rw,relatime,data=ordered 0 0
$ sudo -u telegraf stat /home
```
It may be desired to use POSIX ACLs to provide additional access:
```
sudo setfacl -R -m u:telegraf:X /var/lib/docker/volumes/
```
### Example Output:
```
disk,fstype=hfs,mode=ro,path=/ free=398407520256i,inodes_free=97267461i,inodes_total=121847806i,inodes_used=24580345i,total=499088621568i,used=100418957312i,used_percent=20.131039916242397 1453832006274071563
disk,fstype=devfs,mode=rw,path=/dev free=0i,inodes_free=0i,inodes_total=628i,inodes_used=628i,total=185856i,used=185856i,used_percent=100 1453832006274137913
disk,fstype=autofs,mode=rw,path=/net free=0i,inodes_free=0i,inodes_total=0i,inodes_used=0i,total=0i,used=0i,used_percent=0 1453832006274157077
disk,fstype=autofs,mode=rw,path=/home free=0i,inodes_free=0i,inodes_total=0i,inodes_used=0i,total=0i,used=0i,used_percent=0 1453832006274169688
```
[statfs]: http://man7.org/linux/man-pages/man2/statfs.2.html