前言

在传统的k8s集群中，我们都是使用docker engine做为底层的容器管理软件的，而docker engine因为不是k8s亲生的解决方案，所以实际使用中会有更多的分层。之前我们也讲过，k8s为了调用docker engine，专门写了一个dockershim做为CRI，而在1.20版本的时候，k8s就宣布停止更新dockershim了，也就是说再往后的版本就不推荐使用k8s+dockershim+docker engine的方案了。

而k8s官方比较推荐的解决方案中，官方比较推荐的是cri-o或者containerd，前者是基于开放容器计划(OCI)的实现，后者是基于docker的containerd，后脱离出来进行独立开发的组件，现归属于CNCF组织。

CRI-O vs containerd vs docker daemon

这三者有啥区别呢？

首先，cri-o是cri的实现，可以直接调用底层的runc

其次，containerd是CRI-Containerd的实现，可以调用底层的runc

而docker则需要先调用dockershim，然后调用docker，再调用containerd，最后调用底层的runc

三者区别如图：

k8s+crio+podman实现

podman安装

可参考我前一篇文章

docker的平替–podman - eryoung2 - 博客园

三台机都需要安装podman

k8s的安装

可参考我另一篇文章

kubernetes 搭建集群 - eryoung2 - 博客园

三台机都需要安装kubelet/kubeadm/kubectl，并启动kubelet

cri-o的安装

Ubuntu(18.04)

1 准备

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modprobe overlay  # 打开overlay
modprobe br_netfilter  # 打开netfilter
cat > /etc/sysctl.d/99-kubernetes-cri.conf <<EOF #内核处理
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF
sysctl --system
swapoff -a #kube scheduler要求关闭swap

2 安装CRI-O

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# 指定版本
OS=xUbuntu_18.04
CRIO_VERSION=1.23
# 加源
echo "deb https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/$OS/ /"|sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable.list
echo "deb http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable:/cri-o:/$CRIO_VERSION/$OS/ /"|sudo tee /etc/apt/sources.list.d/devel:kubic:libcontainers:stable:cri-o:$CRIO_VERSION.list
# 加key
curl -L https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable:cri-o:$CRIO_VERSION/$OS/Release.key | sudo apt-key add -
curl -L https://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable/$OS/Release.key | sudo apt-key add -
# 安装
sudo apt update -y
sudo apt install cri-o cri-o-runc cri-tools -y

3 检查CRI-O

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root@home:~# apt show cri-o
Package: cri-o
Version: 1.23.3~0
Priority: optional
Section: devel
Maintainer: Peter Hunt <haircommander@fedoraproject.org>
Installed-Size: 98.3 MB
Depends: libgpgme11, libseccomp2, conmon, containers-common (>= 0.1.27) | golang-github-containers-common, tzdata
Suggests: cri-o-runc | runc (>= 1.0.0), containernetworking-plugins
Replaces: cri-o-1.19, cri-o-1.20, cri-o-1.21, cri-o-1.22
Homepage: https://github.com/cri-o/cri-o
Download-Size: 19.9 MB
APT-Manual-Installed: yes
APT-Sources: http://download.opensuse.org/repositories/devel:/kubic:/libcontainers:/stable:/cri-o:/1.23/xUbuntu_18.04  Packages
Description: OCI-based implementation of Kubernetes Container Runtime Interface.

N: Ignoring file 'ystemctlqq' in directory '/etc/apt/sources.list.d/' as it has no filename extension
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systemctl enable crio.service
systemctl start crio.service
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root@home:~# systemctl status crio
● crio.service - Container Runtime Interface for OCI (CRI-O)
   Loaded: loaded (/usr/lib/systemd/system/crio.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2022-07-13 01:26:03 CST; 16h ago
     Docs: https://github.com/cri-o/cri-o
 Main PID: 5338 (crio)
    Tasks: 15
   CGroup: /system.slice/crio.service
           └─5338 /usr/bin/crio

4 使用cri-o

查看状态

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root@home:~# crictl info
{
  "status": {
    "conditions": [
      {
        "type": "RuntimeReady",
        "status": true,
        "reason": "",
        "message": ""
      },
      {
        "type": "NetworkReady",
        "status": true,
        "reason": "",
        "message": ""
      }
    ]
  }
}

查看镜像

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root@home:~# crictl images
IMAGE                                TAG                 IMAGE ID            SIZE
docker.io/calico/cni                 v3.23.2             a87d3f6f1b8fd       263MB
docker.io/calico/node                v3.23.2             a3447b26d32c7       224MB
docker.io/library/nginx              latest              41b0e86104ba6       146MB
k8s.gcr.io/coredns/coredns           v1.8.6              a4ca41631cc7a       47MB
k8s.gcr.io/etcd                      3.5.3-0             aebe758cef4cd       301MB
k8s.gcr.io/kube-apiserver            v1.24.2             d3377ffb7177c       131MB
k8s.gcr.io/kube-controller-manager   v1.24.2             34cdf99b1bb3b       121MB
k8s.gcr.io/kube-proxy                v1.24.2             a634548d10b03       112MB
k8s.gcr.io/kube-scheduler            v1.24.2             5d725196c1f47       52.3MB
k8s.gcr.io/pause                     3.6                 6270bb605e12e       690kB
k8s.gcr.io/pause                     3.7                 221177c6082a8       718kB

Centos(7)

1 准备

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VERSION=1.22
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable/CentOS_7/devel:kubic:libcontainers:stable.repo
sudo curl -L -o /etc/yum.repos.d/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo https://download.opensuse.org/repositories/devel:kubic:libcontainers:stable:cri-o:${VERSION}/CentOS_7/devel:kubic:libcontainers:stable:cri-o:${VERSION}.repo

2 安装

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yum update -y
yum install cri-o cri-tools -y

3 查看cri-o版本

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[root@node1 systemd]# rpm -qi cri-o
Name        : cri-o
Epoch       : 0
Version     : 1.22.5
Release     : 2.2.el7
Architecture: x86_64
Install Date: 2022年07月13日 星期三 01时36分47秒
Group       : Unspecified
Size        : 236845729
License     : ASL 2.0
Signature   : RSA/SHA256, 2022年07月10日 星期日 12时53分28秒, Key ID 4d64390375060aa4
Source RPM  : cri-o-1.22.5-2.2.el7.src.rpm
Build Date  : 2022年07月10日 星期日 12时53分00秒
Build Host  : sheep87
Relocations : (not relocatable)
Vendor      : obs://build.opensuse.org/devel:kubic
URL         : https://github.com/cri-o/cri-o
Summary     : Open Container Initiative-based implementation of Kubernetes Container Runtime Interface
Description :
Open Container Initiative-based implementation of Kubernetes Container Runtime
Interface.

4 启动cri-o

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systemctl enable --now cri-o

5 查看cri-o状态

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[root@node1 systemd]# systemctl status crio
● crio.service - Container Runtime Interface for OCI (CRI-O)
   Loaded: loaded (/usr/lib/systemd/system/crio.service; enabled; vendor preset: disabled)
   Active: active (running) since 三 2022-07-13 01:41:06 CST; 16h ago
     Docs: https://github.com/cri-o/cri-o
 Main PID: 24127 (crio)
    Tasks: 15
   Memory: 13.7M
   CGroup: /system.slice/crio.service
           └─24127 /usr/bin/crio

三台机都安装cri-o并启动。

K8S启动

在master上，跑下列命令：

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kubeadm init --apiserver-advertise-address 192.168.1.150 --apiserver-bind-port 6443 --kubernetes-version 1.24.2 --pod-network-cidr 10.244.0.0/16

然后等5分钟，就创建了一个k8s集群的master node。

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Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.150:6443 --token gjxt6y.0wljlhfkjz90v12m --discovery-token-ca-cert-hash sha256:d69fc5929e442210c97ab85c05a8c2906f5819a74d5b0fa3481032d6a8f3fc07

在三台机上跑这三条命令

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mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

否则会报错。

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The connection to the server localhost:8080 was refused - did you specify the right host or port?

检查集群

在以上所有内容都完成之后，我们可以看一下nodes或者pods

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root@home:~# kubectl get nodes
NAME    STATUS   ROLES           AGE    VERSION
home    Ready    control-plane   179m   v1.24.2
node1   Ready    <none>          179m   v1.24.2
node2   Ready    <none>          179m   v1.24.2
root@home:~# kubectl get pods -A
NAMESPACE     NAME                           READY   STATUS    RESTARTS   AGE
kube-system   coredns-6d4b75cb6d-4wxjh       1/1     Running   0          179m
kube-system   coredns-6d4b75cb6d-7qxpv       1/1     Running   0          179m
kube-system   etcd-home                      1/1     Running   2          3h
kube-system   kube-apiserver-home            1/1     Running   2          3h
kube-system   kube-controller-manager-home   1/1     Running   2          3h
kube-system   kube-proxy-9w7mf               1/1     Running   0          179m
kube-system   kube-proxy-hpw6c               1/1     Running   0          179m
kube-system   kube-proxy-tbpr8               1/1     Running   0          179m
kube-system   kube-scheduler-home            1/1     Running   2          3h

鸣谢

  1. Using CRI-O as container runtime for Kubernetes

  2. Ubuntu安装cri-o

  3. Install CRI-O Container Runtime on CentOS 8 / CentOS 7 | ComputingForGeeks