docker change cgroup driver to systemd - linux

Question

I want Docker to start with systemd cgroup driver. For some reason it is using only cgroupfs on my CentOS 7 server.
Here is startup config file.
# systemctl cat docker
# /usr/lib/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.com
After=network.target
Wants=docker-storage-setup.service
Requires=docker-cleanup.timer
[Service]
Type=notify
NotifyAccess=all
EnvironmentFile=-/etc/sysconfig/docker
EnvironmentFile=-/etc/sysconfig/docker-storage
EnvironmentFile=-/etc/sysconfig/docker-network
Environment=GOTRACEBACK=crash
Environment=DOCKER_HTTP_HOST_COMPAT=1
Environment=PATH=/usr/libexec/docker:/usr/bin:/usr/sbin
ExecStart=/usr/bin/dockerd-current \
--add-runtime docker-runc=/usr/libexec/docker/docker-runc-current \
--default-runtime=docker-runc \
--exec-opt native.cgroupdriver=systemd \
--userland-proxy-path=/usr/libexec/docker/docker-proxy-current \
$OPTIONS \
$DOCKER_STORAGE_OPTIONS \
$DOCKER_NETWORK_OPTIONS \
$ADD_REGISTRY \
$BLOCK_REGISTRY \
$INSECURE_REGISTRY
ExecReload=/bin/kill -s HUP $MAINPID
LimitNOFILE=1048576
LimitNPROC=1048576
LimitCORE=infinity
TimeoutStartSec=0
Restart=on-abnormal
MountFlags=slave
[Install]
WantedBy=multi-user.target
# /etc/systemd/system/docker.service.d/docker-thinpool.conf
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd --storage-driver=devicemapper --storage-opt=dm.thinpooldev=/dev/mapper/docker-thinpool \
--storage-opt=dm.use_deferred_removal=true --storage-opt=dm.use_deferred_deletion=true
EOF
When I start Docker, it's running like this:
# ps -fed | grep docker
root 8436 1 0 19:13 ? 00:00:00 /usr/bin/dockerd-current --storage-driver=devicemapper --storage-opt=dm.thinpooldev=/dev/mapper/docker-thinpool --storage-opt=dm.use_deferred_removal=true --storage-opt=dm.use_deferred_deletion=true
root 8439 8436 0 19:13 ? 00:00:00 /usr/bin/docker-containerd-current -l unix:///var/run/docker/libcontainerd/docker-containerd.sock --shim docker-containerd-shim --metrics-interval=0 --start-timeout 2m --state-dir /var/run/docker/libcontainerd/containerd --runtime docker-runc
Here is the output of docker info:
# docker info
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 1
Server Version: 1.12.6
Storage Driver: devicemapper
Pool Name: docker-thinpool
Pool Blocksize: 524.3 kB
Base Device Size: 10.74 GB
Backing Filesystem: xfs
Data file:
Metadata file:
Data Space Used: 185.6 MB
Data Space Total: 1.015 GB
Data Space Available: 829.4 MB
Metadata Space Used: 77.82 kB
Metadata Space Total: 8.389 MB
Metadata Space Available: 8.311 MB
Thin Pool Minimum Free Space: 101.2 MB
Udev Sync Supported: true
Deferred Removal Enabled: true
Deferred Deletion Enabled: true
Deferred Deleted Device Count: 0
Library Version: 1.02.135-RHEL7 (2016-11-16)
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: null bridge overlay host
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 3.10.0-514.16.1.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
Number of Docker Hooks: 2
CPUs: 1
Total Memory: 992.7 MiB
Name: master
ID: 6CFR:H7SN:MEU7:PNJH:UMSO:6MNE:43Q5:SF4K:Z25I:BKHP:53U4:63SO
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Insecure Registries:
127.0.0.0/8
Registries: docker.io (secure)
How can I make it run with systemd?
Thanks
SR

Answer 1

A solution that does not involve editing systemd units or drop-ins would be to create (or edit) the /etc/docker/daemon.json configuration file and to include the following:
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
After saving it, restart your docker service.
sudo systemctl restart docker
This solution obviously is only feasible if you would want to apply this system-wide.

Answer 2

Since I have two configuration file I need to add the entry in the second config file also -- /etc/systemd/system/docker.service.d/docker-thinpool.conf:
--exec-opt native.cgroupdriver=systemd \

Answer 3

Just to add, cgroupfs is dockers own control group manager. However, for the majority of Linux distributions ssytemd is the default init system now and systemd has tight integration with Linux control groups and In Kubernetes site, they recommend using systemd (see below) as using cgroupfs along with systemd seems to be non-optimal
So it is better to use systemd then for cgroup managment. kubelet is configured by default to use systemd. So it is easier and better to change Docker to use the systemd Cgroup driver
A history of this overlap is here https://lwn.net/Articles/676831/
In Kubernetes site, they recommend using systemd https://kubernetes.io/docs/setup/production-environment/container-runtimes/
Cgroup drivers When systemd is chosen as the init system for a Linux
distribution, the init process generates and consumes a root control
group (cgroup) and acts as a cgroup manager. Systemd has a tight
integration with cgroups and will allocate cgroups per process. It’s
possible to configure your container runtime and the kubelet to use
cgroupfs. Using cgroupfs alongside systemd means that there will then
be two different cgroup managers.
Control groups are used to constrain resources that are allocated to
processes. A single cgroup manager will simplify the view of what
resources are being allocated and will by default have a more
consistent view of the available and in-use resources. When we have
two managers we end up with two views of those resources. We have seen
cases in the field where nodes that are configured to use cgroupfs for
the kubelet and Docker, and systemd for the rest of the processes
running on the node becomes unstable under resource pressure.

Answer 4

OS: Centos 7.4 As kubernetes 1.23.1 recommend to use cgroup systemd, and docker 20.10.20 use cgroup cgroupfs. So, you have to change docker service file.
step1: Stop docker service
systemctl stop docker
step2: change on files /etc/systemd/system/multi-user.target.wants/docker.service and /usr/lib/systemd/system/docker.service
From :
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
TO:
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock --exec-opt native.cgroupdriver=systemd
step3: start docker service and kubelet
systemctl start docker
kubeadm init phase kubelet-start

Answer 5

Make sure you are logged in as root and execute the below two commands :
echo '{"exec-opts": ["native.cgroupdriver=systemd"]}' >> /etc/docker/daemon.json
systemctl restart docker

Answer 6

Try to restart the docker service:
systemctl daemon-reload
systemctl restart docker.service