Fix HOST_MOUNT_PREFIX in docker with disk input (#3529)

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Daniel Nelson 2017-12-01 11:21:39 -08:00 committed by GitHub
parent e400ec2b57
commit 7f66863b87
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 38 additions and 8 deletions

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@ -1,5 +1,24 @@
# Frequently Asked Questions
### Q: How can I monitor the Docker Engine Host from within a container?
You will need to setup several volume mounts as well as some environment
variables:
```
docker run --name telegraf
-v /:/hostfs:ro
-v /etc:/hostfs/etc:ro
-v /proc:/hostfs/proc:ro
-v /sys:/hostfs/sys:ro
-v /var/run/utmp:/var/run/utmp:ro
-e HOST_ETC=/hostfs/etc
-e HOST_PROC=/hostfs/proc
-e HOST_SYS=/hostfs/sys
-e HOST_MOUNT_PREFIX=/hostfs
telegraf
```
### Q: Why do I get a "no such host" error resolving hostnames that other
programs can resolve?

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@ -20,9 +20,11 @@ Additionally, the behavior of resolving the `mount_points` can be configured by
When present, this variable is prepended to the mountpoints discovered by the plugin before retrieving stats.
The prefix is stripped from the reported `path` in the measurement.
This settings is useful when running `telegraf` inside a docker container to report host machine metrics.
In this case, the host's root volume should be mounted into the container and the `HOST_MOUNT_PREFIX` and `HOST_ETC` environment variables set.
In this case, the host's root volume should be mounted into the container and the `HOST_MOUNT_PREFIX` and `HOST_PROC` environment variables set.
`docker run -v /:/hostfs:ro -e HOST_MOUNT_PREFIX=/hostfs -e HOST_ETC=/hostfs/etc telegraf`
```
docker run -v /:/hostfs:ro -e HOST_MOUNT_PREFIX=/hostfs -e HOST_PROC=/hostfs/proc telegraf
```
### Measurements & Fields:

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@ -62,8 +62,6 @@ func TestDiskUsage(t *testing.T) {
mps.On("Partitions", true).Return(psAll, nil)
mps.On("OSGetenv", "HOST_MOUNT_PREFIX").Return("")
mps.On("OSStat", "/").Return(MockFileInfo{}, nil)
mps.On("OSStat", "/home").Return(MockFileInfo{}, nil)
mps.On("PSDiskUsage", "/").Return(&duAll[0], nil)
mps.On("PSDiskUsage", "/home").Return(&duAll[1], nil)

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@ -2,6 +2,7 @@ package system
import (
"os"
"strings"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
@ -84,6 +85,10 @@ func (s *systemPS) DiskUsage(
for _, filter := range fstypeExclude {
fstypeExcludeSet[filter] = true
}
paths := make(map[string]bool)
for _, part := range parts {
paths[part.Mountpoint] = true
}
// Autofs mounts indicate a potential mount, the partition will also be
// listed with the actual filesystem when mounted. Ignore the autofs
@ -92,6 +97,7 @@ func (s *systemPS) DiskUsage(
var usage []*disk.UsageStat
var partitions []*disk.PartitionStat
hostMountPrefix := s.OSGetenv("HOST_MOUNT_PREFIX")
for i := range parts {
p := parts[i]
@ -110,15 +116,20 @@ func (s *systemPS) DiskUsage(
continue
}
mountpoint := s.OSGetenv("HOST_MOUNT_PREFIX") + p.Mountpoint
if _, err := s.OSStat(mountpoint); err != nil {
// If there's a host mount prefix, exclude any paths which conflict
// with the prefix.
if len(hostMountPrefix) > 0 &&
!strings.HasPrefix(p.Mountpoint, hostMountPrefix) &&
paths[hostMountPrefix+p.Mountpoint] {
continue
}
du, err := s.PSDiskUsage(mountpoint)
du, err := s.PSDiskUsage(p.Mountpoint)
if err != nil {
continue
}
du.Path = p.Mountpoint
du.Path = strings.TrimPrefix(p.Mountpoint, hostMountPrefix)
du.Fstype = p.Fstype
usage = append(usage, du)
partitions = append(partitions, &p)