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5.2.1.3. Software Configuration

This section describes the setup and configuration of Kubernetes components that ensure proper cluster operation.

Configuration of containerd

● Required

Component configuration steps

  • Component configuration
  • Systemd Unit setup for the component
  • Systemd Unit start
Note

This section depends on the following documents:

Component configuration

Creating working directories

mkdir -p /etc/containerd/
mkdir -p /etc/containerd/conf.d
mkdir -p /etc/containerd/certs.d

Base configuration file

cat <<"EOF" > /etc/containerd/config.toml
version = 2
imports = ["/etc/containerd/conf.d/*.toml"]
EOF

Custom configuration file template

cat <<"EOF" > /etc/containerd/conf.d/in-cloud.toml
version = 2
[plugins]
  [plugins."io.containerd.grpc.v1.cri"]
    sandbox_image = "registry.k8s.io/pause:3.9"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
    runtime_type = "io.containerd.runc.v2"
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
    SystemdCgroup = true
  [plugins."io.containerd.grpc.v1.cri".registry]
    config_path = "/etc/containerd/certs.d/"
EOF

Systemd Unit setup for the component

Delegate=yes delegates cgroup subsystem management to the container runtime (required for proper Kubernetes operation). KillMode=process ensures that when the service is stopped, only the main containerd process is terminated, not the child containers. OOMScoreAdjust=-999 protects the process from OOM Killer — without the runtime, all containers on the node become unmanageable.

cat <<EOF > /usr/lib/systemd/system/containerd.service
[Unit]
Description=containerd container runtime
Documentation=https://containerd.io
After=network.target local-fs.target containerd-install.service runc-install.service
Wants=containerd-install.service runc-install.service

[Service]
ExecStartPre=-/sbin/modprobe overlay
ExecStart=/usr/local/bin/containerd

Type=notify
Delegate=yes
KillMode=process
Restart=always
RestartSec=5
LimitNPROC=infinity
LimitCORE=infinity
LimitNOFILE=infinity
TasksMax=infinity
OOMScoreAdjust=-999

[Install]
WantedBy=multi-user.target
EOF
systemctl enable containerd
systemctl start containerd

Configuration verification

Configuration verification
tree /etc/containerd/
Command output
/etc/containerd/
├── certs.d
├── conf.d
│   └── cloud.toml
└── config.toml
systemctl status containerd
Command output
● containerd.service - containerd container runtime
      Loaded: loaded (/usr/lib/systemd/system/containerd.service; enabled; preset: enabled)
      Active: active (running) since Tue 2024-12-31 17:26:21 UTC; 2min 30s ago
        Docs: https://containerd.io
    Main PID: 839 (containerd)
      Tasks: 7 (limit: 2274)
      Memory: 62.0M (peak: 62.5M)
        CPU: 375ms
      CGroup: /system.slice/containerd.service
              └─839 /usr/local/bin/containerd

***** level=info msg="Start subscribing containerd event"
***** level=info msg="Start recovering state"
***** level=info msg="Start event monitor"
***** level=info msg="Start snapshots syncer"
***** level=info msg="Start cni network conf syncer for default"
***** level=info msg="Start streaming server"
***** level=info msg=serving... address=/run/containerd/containerd.sock.ttrpc
***** level=info msg=serving... address=/run/containerd/containerd.sock
***** level=info msg="containerd successfully booted in 0.065807s"
***** Started containerd.service - containerd container runtime.