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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4 changed files with 38 additions and 8 deletions

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@ -1,5 +1,24 @@
# Frequently Asked Questions # 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 ### Q: Why do I get a "no such host" error resolving hostnames that other
programs can resolve? 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. 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. 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. 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: ### Measurements & Fields:

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

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