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Last pushed: 5 days ago
Short Description
Real-time performance monitoring
Full Description

netdata

Dockerfile for building and running a netdata deamon for your host instance.

Netdata monitors your server with thoughts of performance and memory usage, providing detailed insight into
very recent server metrics. It's nice, and now it's also dockerized.

More info about project: https://github.com/firehol/netdata

Using

docker run -d --cap-add SYS_PTRACE \
           -v /proc:/host/proc:ro \
           -v /sys:/host/sys:ro \
           -p 19999:19999 titpetric/netdata

Open a browser on http://server:19999/ and watch how your server is doing.

Monitoring docker container metrics

Netdata supports fetching container data from docker.sock. You can forward it to the netdata container with:

-v /var/run/docker.sock:/var/run/docker.sock

This will allow netdata to resolve container names.

Note: forwarding docker.sock exposes the administrative docker API. If due to some security issue access has been obtained to the container, it will expose full docker API, allowing to stop, create or delete containers, as well as download new images in the host.

TL;DR If you care about security, consider forwarding a secure docker socket with docker-proxy-acl

Monitoring docker notes on some systems (Debian jessie)

On debian jessie only 'cpu' and 'disk' metrics show up under individual docker containers. To get the memory metric, you will have to add cgroup_enable=memory swapaccount=1 to /etc/default/grub, appending the GRUB_CMDLINE_LINUX_DEFAULT variable:

$ cat /etc/default/grub  | grep GRUB_CMDLINE_LINUX_DEFAULT
GRUB_CMDLINE_LINUX_DEFAULT="quiet cgroup_enable=memory swapaccount=1"

After rebooting your linux instance, the memory accounting subsystem of the kernel will be enabled. Netdata will pick up additional metrics for the containers when it starts.

Environment variables

It's possible to pass a NETDATA_PORT environment variable with -e, to start up netdata on a different port.

docker run -e NETDATA_PORT=80 [...]

Some explanation is in order

Docker needs to run with the SYS_PTRACE capability. Without it, the mapped host/proc filesystem
is not fully readable to the netdata deamon, more specifically the "apps" plugin:

16-01-12 07:58:16: ERROR: apps.plugin: Cannot process /host/proc/1/io (errno 13, Permission denied)

See the following link for more details: /proc/1/environ is unavailable in a container that is not priviledged

Limitations

In addition to the above requirements and limitations, monitoring the complete network interface list of
the host is not possible from within the Docker container. If you're running netdata and want to graph
all the interfaces available on the host, you will have to use --net=host mode.

See the following link for more details: network interfaces missing when mounting proc inside a container

Additional notes

Netdata provides monitoring via a plugin architecture. This plugin supports many projects that don't
provide data over the /proc filesystem. When you're running netdata in the container, you will have
difficulty providing many of these paths to the netdata container.

What you do get (even with the docker version) is:

  • Host CPU statististics
  • Host Network I/O, QoS
  • Host Disk I/O
  • Applications monitoring
  • Container surface metrics (cpu/disk per name)

You will not get detailed application metrics (mysql, etc.) from other containers or from the host if running netdata in a container. It may be possible to get some of those metrics, but it might not be easy, and most likely not worth it. For most detailed metrics, netdata needs to share the same environment as the application server it monitors. This means it would need to run either in the same container (not even remotely practical), or in the same virtual machine (no containers).

What I can tell you is that it's very stable, and snappy. Godspeed!

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we87
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