Monitor Cgroups (cgroups.plugin)

You can monitor containers and virtual machines using cgroups.

cgroups (or control groups), are a Linux kernel feature that provides accounting and resource usage limiting for processes. When cgroups are bundled with namespaces (i.e. isolation), they form what we usually call containers.

cgroups are hierarchical, meaning that cgroups can contain child cgroups, which can contain more cgroups, etc. All accounting is reported (and resource usage limits are applied) also in a hierarchical way.

To visualize cgroup metrics Netdata provides configuration for cherry-picking the cgroups of interest. By default, Netdata should pick systemd services, all kinds of containers (lxc, docker, etc.) and virtual machines spawn by managers that register them with cgroups (qemu, libvirt, etc.).

The collector also exposes cachestat charts for both regular cgroups and systemd services, mirroring the legacy ebpf.plugin contexts.

Supported Technologies

cgroups.plugin monitors any process that creates Linux cgroups. For the following technologies, Netdata also resolves friendly names (e.g., showing "my-web-app" instead of a raw cgroup path like /sys/fs/cgroup/system.slice/docker-abc123.scope).

The Naming column below indicates whether Netdata can resolve the cgroup path to a human-readable name (e.g., the container name, VM name, or service name):

Technology	Naming
Docker	Yes
Podman	Yes
Kubernetes pods/containers	Yes
Nomad (via Docker)	Yes
AWS ECS (via Docker)	Yes
containerd (via Docker)	Yes
Proxmox QEMU/KVM VMs	Yes
Proxmox LXC containers	Yes
libvirt QEMU/KVM VMs	Yes
libvirt LXC containers	Yes
LXC 4.0+ (including Incus)	Yes
systemd-nspawn	Yes
Systemd services	Yes
KubeVirt VMs (in K8s)	Partial

Technologies that use the above as their underlying infrastructure are also covered. For example:

• OpenShift and other Kubernetes distributions (k3s, RKE, RKE2, MicroK8s, EKS, GKE, AKS) — via Kubernetes cgroup paths
• OpenStack Nova — via libvirt/QEMU cgroup paths
• oVirt / RHV — via libvirt/QEMU cgroup paths

Any other technology creating Linux cgroups is monitored (CPU, memory, disk I/O, network), but will show its raw cgroup path as the name.

Configuring Netdata for cgroups

In general, no additional settings are required. Netdata discovers all available cgroups on the host system and collects their metrics.

How Netdata finds the available cgroups

Linux exposes resource usage reporting and provides dynamic configuration for cgroups, using virtual files (usually) under /sys/fs/cgroup. Netdata reads /proc/self/mountinfo to detect the exact mount point of cgroups.

Netdata rescans directories inside /sys/fs/cgroup for added or removed cgroups every check for new cgroups every seconds (default: 10 seconds).

Hierarchical search for cgroups

Since cgroups are hierarchical, for each of the directories shown above, Netdata walks through the subdirectories recursively searching for cgroups (each subdirectory is another cgroup).

To provide a sensible default for this setting, Netdata uses the following pattern list (patterns starting with ! give a negative match and their order is important: the first matching a path will be used):

[plugin:cgroups]
 search for cgroups in subpaths matching =  !*/init.scope  !*-qemu  !*.libvirt-qemu  !/init.scope  !/system  !/systemd  !/user  !/lxc/*/*  !/lxc.monitor  !/lxc.payload/*/*  !/lxc.payload.*  *

So, we disable checking for child cgroups in systemd internal cgroups (systemd services are monitored by Netdata), user cgroups (normally used for desktop and remote user sessions), qemu virtual machines (child cgroups of virtual machines) and init.scope. All others are enabled.

Enabled cgroups

To provide a sensible default, Netdata uses the following pattern list:

• Checks the pattern against the path of the cgroup

  [plugin:cgroups]
   enable by default cgroups matching =  !*/init.scope  !/system.slice/run-*.scope  *user.slice/docker-*  !*user.slice*  *.scope  !/machine.slice/*/.control  !/machine.slice/*/payload*  !/machine.slice/*/supervisor  /machine.slice/*.service  */kubepods/pod*/*  */kubepods/*/pod*/*  */*-kubepods-pod*/*  */*-kubepods-*-pod*/*  !*kubepods*  !*kubelet*  !*/vcpu*  !*/emulator  !*.mount  !*.partition  !*.service  !*.service/udev  !*.socket  !*.slice  !*.swap  !*.user  !/  !/docker  !*/libvirt  !/lxc  !/lxc/*/*  !/lxc.monitor*  !/lxc.pivot  !/lxc.payload  !*lxcfs.service/.control  !/machine  !/qemu  !/system  !/systemd  !/user  *

• Checks the pattern against the name of the cgroup (as you see it on the dashboard)

  [plugin:cgroups]
   enable by default cgroups names matching = *

Renaming is configured with the following options:

[plugin:cgroups]
 run script to rename cgroups matching =  !/  !*.mount  !*.socket  !*.partition  /machine.slice/*.service  !*.service  !*.slice  !*.swap  !*.user  !init.scope  !*.scope/vcpu*  !*.scope/emulator  *.scope  *docker*  *lxc*  *qemu*  */kubepods/pod*/*  */kubepods/*/pod*/*  */*-kubepods-pod*/*  */*-kubepods-*-pod*/*  !*kubepods*  !*kubelet*  *.libvirt-qemu  *
 script to get cgroup names = /usr/libexec/netdata/plugins.d/cgroup-name.sh

The additional pattern list serves to limit the number of times the script will be called. Without it, the script might be called thousands of times, depending on the number of cgroups available in the system.

The above pattern list is matched against the path of the cgroup. For matched cgroups, Netdata calls the script cgroup-name.sh.in to get its name. This script queries docker, kubectl, podman, or applies heuristics to find a name for the cgroup.

Note on Podman container names

Podman's security model is a lot more restrictive than Docker's, so Netdata will not be able to detect container names out of the box unless they were started by the same user as Netdata itself.

If Podman is used in "rootful" mode, it's also possible to use podman system service to grant Netdata access to container names. To do this, ensure podman system service is running and Netdata has access to /run/podman/podman.sock (the default permissions as specified by upstream are 0600, with owner root, so you will have to adjust the configuration).

Docker Socket Proxy (HAProxy) or CetusGuard can also be used to give Netdata restricted access to the socket. Note that PODMAN_HOST in Netdata's environment should be set to the proxy's URL in this case.

Customizing cgroup names

When Netdata resolves a cgroup to a friendly name (a Docker container name, a Kubernetes pod name, and so on), you can override the resolved name with your own value by setting a label or annotation with the key netdata.cloud/cgroup.name. The value becomes the cgroup's display name, and Netdata derives the chart identifier from it.

This is useful when the auto-resolved name is a raw container ID, a long auto-generated string, or simply not the name you want to see on the dashboard — for example, to turn a chart name like cgroup_twxae02wzkyy2d19gz4dsj6a-storefront-green-1.cpu into cgroup_storefront-green.cpu.

The override changes only the cgroup-name segment of a chart name such as cgroup_<name>.cpu. It does not affect the chart-type prefix (cgroup_), the metric suffix (e.g. .cpu), or the @<node> identifier shown when metrics come from a different node.

Docker and Podman containers

Add a container label named netdata.cloud/cgroup.name:

docker run --label netdata.cloud/cgroup.name=my-web-app ...

With Docker Compose, set it under the service labels:

services:
  web:
    image: nginx
    labels:
      - "netdata.cloud/cgroup.name=my-web-app"

Netdata reads the label from the same docker inspect / podman inspect output it already uses for name resolution and applies the override. Podman works the same way (see the Podman note for the socket access requirement).

Kubernetes pods

For controller-managed pods (Deployments, StatefulSets, and similar), add the annotation in the pod template so it persists across pod restarts:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: storefront
spec:
  template:
    metadata:
      annotations:
        netdata.cloud/cgroup.name: "storefront-green"

To annotate a running pod directly (does not persist when the pod is replaced by a controller):

kubectl annotate pods <pod-name> netdata.cloud/cgroup.name=<desired-name>

Netdata extracts netdata.cloud/* annotations from pod metadata and uses netdata.cloud/cgroup.name to override the resolved name.

Verifying the result and troubleshooting

You can check the chart names Netdata created through the Agent's /api/v3/contexts endpoint and filter for the cgroup_ prefix to confirm the override took effect. Use the chart name shown by that endpoint when referencing the chart in API queries.

note

If you see a long alphanumeric string such as twxae02wzkyy2d19gz4dsj6a- at the start of a cgroup's chart name, that string is part of the resolved name itself (typically a container ID or Kubernetes UID from the cgroup path), not a prefix added by Netdata. Setting netdata.cloud/cgroup.name replaces it with your own value.

If no override is set and Netdata cannot resolve a friendly name via Docker, Kubernetes, or Podman, the raw cgroup path is used as the display name.

Alerts

CPU and memory limits are watched and used to raise alerts. Memory usage for every cgroup is checked against ram and ram+swap limits. CPU usage for every cgroup is checked against cpuset.cpus and cpu.cfs_period_us + cpu.cfs_quota_us pair assigned for the cgroup. Configuration for the alerts is available in health.d/cgroups.conf file.

Monitoring systemd services

Netdata monitors systemd services.

Monitored systemd service metrics

• CPU utilization
• Memory
• Writeback Memory
• Memory Paging I/O
• Memory Page Faults
• Memory Limit Failures
• Used Memory
• Disk Read/Write Bandwidth
• Disk Read/Write Operations
• Throttle Disk Read/Write Bandwidth
• Throttle Disk Read/Write Operations
• Queued Disk Read/Write Operations
• Merged Disk Read/Write Operations
• Number of Processes

How to enable cgroup accounting on systemd systems that is by default disabled

note

On systems using cgroup v2 (the default on Ubuntu 22.04+, Fedora 31+, RHEL 9+, and other modern distributions), memory accounting is always enabled — no kernel boot parameters or systemd changes are needed. To check which cgroup version is active: stat -fc %T /sys/fs/cgroup returns cgroup2fs for cgroup v2 or tmpfs for cgroup v1.

You can verify there is no accounting enabled, by running systemd-cgtop. The program will show only resources for cgroup /, but all services will show nothing.

To enable cgroup accounting, execute this:

sed -e 's|^#Default\(.*\)Accounting=.*$|Default\1Accounting=yes|g' /etc/systemd/system.conf >/tmp/system.conf

To see the changes it made, run this:

# diff /etc/systemd/system.conf /tmp/system.conf
40,44c40,44
< #DefaultCPUAccounting=no
< #DefaultIOAccounting=no
< #DefaultBlockIOAccounting=no
< #DefaultMemoryAccounting=no
< #DefaultTasksAccounting=yes
---
> DefaultCPUAccounting=yes
> DefaultIOAccounting=yes
> DefaultBlockIOAccounting=yes
> DefaultMemoryAccounting=yes
> DefaultTasksAccounting=yes

If you are happy with the changes, run:

# copy the file to the right location
sudo cp /tmp/system.conf /etc/systemd/system.conf

# restart systemd to take it into account
sudo systemctl daemon-reexec

Note: systemctl daemon-reload does not reload systemd's own configuration — use systemctl daemon-reexec instead.

Now, when you run systemd-cgtop, services will start reporting usage (if it does not, restart any service to wake it up). Refresh your Netdata dashboard, and you will have the charts too.

In case memory accounting is missing (cgroup v1 systems), you will need to enable it at your kernel, by appending the following kernel boot options and rebooting:

cgroup_enable=memory swapaccount=1

You can add the above, directly at the linux line in your /boot/grub/grub.cfg or appending them to the GRUB_CMDLINE_LINUX in /etc/default/grub (in which case you will have to run update-grub before rebooting). On DigitalOcean debian images you may have to set it at /etc/default/grub.d/50-cloudimg-settings.cfg.

Which systemd services are monitored by Netdata is determined by the following pattern list:

[plugin:cgroups]
 cgroups to match as systemd services =  !/system.slice/*.service/*.service  /system.slice/*.service

Monitoring ephemeral containers

Netdata monitors containers automatically when it is installed at the host, or when it is installed in a container that has access to the /proc and /sys filesystems of the host.

Network interfaces and cgroups (containers) are self-cleaned. When a network interface or container stops, Netdata might log a few errors in error.log complaining about files it cannot find, but immediately:

1. It will detect this is a removed container or network interface
2. It will freeze/pause all alerts for them
3. It will mark their charts as obsolete
4. Obsolete charts are not be offered on new dashboard sessions (so hit F5 and the charts are gone)
5. Existing dashboard sessions will continue to see them, but of course they will not refresh
6. Obsolete charts will be removed from memory, 1 hour after the last user viewed them (configurable) with [db].cleanup obsolete charts after = 3600 (at netdata.conf).

Monitored container metrics

• CPU Usage
• CPU Usage within the limits
• CPU Throttled Runnable Periods
• CPU Throttled Time Duration
• CPU Time Relative Share
• CPU Usage Per Core
• Memory Usage
• Writeback Memory
• Memory Activity
• Memory Page Faults
• Used RAM within the limits
• Memory Utilization
• Memory Limit Failures
• Used Memory
• I/O Bandwidth (all disks)
• Serviced I/O Operations (all disks)
• Throttle I/O Bandwidth (all disks)
• Throttle Serviced I/O Operations (all disks)
• Queued I/O Operations (all disks)
• Merged I/O Operations (all disks)
• CPU some pressure
• CPU some pressure stall time
• CPU full pressure
• CPU full pressure stall time
• Memory some pressure
• Memory some pressure stall time
• Memory full pressure
• Memory full pressure stall time
• IRQ some pressure
• IRQ some pressure stall time
• IRQ full pressure
• IRQ full pressure stall time
• I/O some pressure
• I/O some pressure stall time
• I/O full pressure
• I/O full pressure stall time
• Number of processes

Network interfaces inside containers are discovered and monitored by the cgroups plugin using cgroup-network-helper.sh.