Overview

containerd is designed to built with a larger system like kubernetes. To see the overview, it’s better to check something like

As the above video shows, it depends on plugins or runtime outside of its core by gRPC or the light weight gRPC (ttRPC), like

runc for container runtime
- runc is a tool to manage containers on Linux following the OCI specification

Install

Following the official document, install a containerd from the official binaries.

curl -sLO https://github.com/containerd/containerd/releases/download/v1.6.14/containerd-1.6.14-linux-amd64.tar.gz
sudo tar Cxzvf /usr/local containerd-1.6.14-linux-amd64.tar.gz

Setup the systemd for the containerd

curl -sLO https://raw.githubusercontent.com/containerd/containerd/main/containerd.service
sudo mkdir -p /usr/local/lib/systemd/system/
sudo mv containerd.service /usr/local/lib/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now containerd

Install runc

curl -sLO https://github.com/opencontainers/runc/releases/download/v1.1.4/runc.amd64
sudo install -m 755 runc.amd64 /usr/local/sbin/runc

Install cni plugins

curl -sLO https://github.com/containernetworking/plugins/releases/download/v1.1.1/cni-plugins-linux-amd64-v1.1.1.tgz
sudo mkdir -p /opt/cni/bin
sudo tar Cxzvf /opt/cni/bin cni-plugins-linux-amd64-v1.1.1.tgz

Run a container by CLI

ctr CLI

Use a ctr CLI to confirm followings:

Pull an image by ctr images pull [image ref]
Confirm the list of local images by ctr images list
Run a container by ctr run [image ref] [container name]
See namespaces by ctr namespaces list. Output result is like
```
sudo ctr namespaces list
NAME    LABELS
default
k8s.io
```
See containers or images on the namespace, add an option --namespace [namespace]

There are other subcommands for

plugins
tasks
snapshots
events
content
leases

nerdctr

nerdctl is a CLI for user friendly CLI compatible with Docker.

To install the version 1.1 of it,

curl -sLO https://github.com/containerd/nerdctl/releases/download/v1.1.0/nerdctl-1.1.0-linux-amd64.tar.gz
tar xzvf nerdctl-1.1.0-linux-amd64.tar.gz
sudo mv nerdctl /usr/local/bin
sudo nerdctl --version

See the list of running containers: nerdctl container list

For example, to show the running containers with some information like its ip address, run following command

nerdctl --namespace k8s.io container list | awk '{ print $1 }' | tail -n +2 | xargs nerdctl --namespace k8s.io container inspect | jq -r '.[] | [.Id,.Path,.Image,.NetworkSettings.IPAddress] | @tsv'

Network configuration

There is an example configuration of CNI for k8s.

sudo su -
cat << EOF | tee /etc/cni/net.d/10-containerd-net.conflist
{
 "cniVersion": "1.0.0",
 "name": "containerd-net",
 "plugins": [
   {
     "type": "bridge",
     "bridge": "cni0",
     "isGateway": true,
     "ipMasq": true,
     "promiscMode": true,
     "ipam": {
       "type": "host-local",
       "ranges": [
         [{
           "subnet": "10.88.0.0/16"
         }]
       ],
       "routes": [
         { "dst": "0.0.0.0/0" },
         { "dst": "::/0" }
       ]
     }
   },
   {
     "type": "portmap",
     "capabilities": {"portMappings": true},
     "externalSetMarkChain": "KUBE-MARK-MASQ"
   }
 ]
}
EOF

After adding the above configuration, it can be checked on a nerdctl network ls command.

$ nerdctl network ls
NETWORK ID    NAME              FILE
              containerd-net    /etc/cni/net.d/10-containerd-net.conflist
              host
              none

$ nerdctl network inspect containerd-net
nerdctl network inspect containerd-net
[
    {
        "Name": "containerd-net",
        "IPAM": {
            "Config": [
                {
                    "Subnet": "<IP ADDRESS>"
                }
            ]
        },
        "Labels": null
    }
]

I couldn’t confirm how to confirm port mapping was configured correctly.

The configuration of the CNI is described in these documents:

Start a container

ctr images pull docker.io/library/redis :alpine
ctr run docker.io/library/redis:alpine redis

With nerdctl, we can run a container like

nerdctl run -d docker.io/library/redis:alpine redis

To deploy a container into a network,

nerdctl run -d --network containerd-net --ip 10.128.128.16 docker.io/library/redis:alpine redis

But I got errors

$ sudo nerdctl run -d --network containerd-net docker.io/library/redis:alpine redis
FATA[0000] failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error running hook #0: error running hook: exit status 1, stdout: , stderr: time="2023-01-02T05:39:33Z" level=fatal msg="failed to call cni.Setup: plugin type=\"bridge\" failed (add): failed to set bridge addr: \"cni0\" already has an IP address different from 10.128.128.1/24"
Failed to write to log, write /var/lib/nerdctl/1935db59/containers/default/8dd436c2b4bfe5f3312aa872e00f61c6253801f25fcd1dfb313858fd625cdc57/oci-hook.createRuntime.log: file already closed: unknown


$ sudo nerdctl run -d --net containerd-net docker.io/library/redis:alpine redis
FATA[0000] failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error running hook #0: error running hook: exit status 1, stdout: , stderr: time="2023-01-02T05:39:43Z" level=fatal msg="failed to call cni.Setup: plugin type=\"bridge\" failed (add): failed to set bridge addr: \"cni0\" already has an IP address different from 10.128.128.1/24"
Failed to write to log, write /var/lib/nerdctl/1935db59/containers/default/8c454b3e839413472a3bdde5351b3772eba644ceb4adfcb6e8871d3837e941e2/oci-hook.createRuntime.log: file already closed: unknown

$ sudo nerdctl run -d --network containerd-net --ip 10.128.128.16 docker.io/library/redis:alpine redis
FATA[0000] failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error running hook #0: error running hook: exit status 1, stdout: , stderr: time="2023-01-02T05:35:48Z" level=fatal msg="failed to call cni.Setup: plugin type=\"bridge\" failed (add): failed to set bridge addr: \"cni0\" already has an IP address different from 10.128.128.1/24"
Failed to write to log, write /var/lib/nerdctl/1935db59/containers/default/77211e02cb8fed8eba40e3922cae75341da2018c219bbc18d5a292561e36fa88/oci-hook.createRuntime.log: file already closed: unknown
plugin type=\"bridge\" failed (add): failed to set bridge addr: \"cni0\" already has an IP address different from 10.128.128.1/24

The cni0 is assigned to NIC.

ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1460 qdisc mq state UP group default qlen 1000
    inet 10.128.15.225/32 brd 10.128.15.225 scope global dynamic ens4
       valid_lft 65941sec preferred_lft 65941sec
3: cni0: <NO-CARRIER,BROADCAST,MULTICAST,PROMISC,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 5e:e7:6c:72:30:eb brd ff:ff:ff:ff:ff:ff
    inet 10.128.0.1/20 brd 10.128.15.255 scope global cni0
       valid_lft forever preferred_lft forever

Last updated on January 25, 2025

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