容器运行时Containerd基础

清疚 2022-11-13 12:28 244阅读 0赞

本文目录：

一、安装Containerd

二、运行一个busybox镜像

三、创建CNI网络

四、使containerd容器具备网络功能

五、与宿主机共享目录

六、与其它容器共享ns

七、docker/containerd并用

## 一、安装Containerd ##

本地安装Containerd：

yum install -y yum-utils
    yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
    yum install -y containerd epel-release
    yum install -y jq

Containerd版本：

[root@containerd ~]# ctr version
    Client:
      Version:  1.4.3
      Revision: 269548fa27e0089a8b8278fc4fc781d7f65a939b
      Go version: go1.13.15
    
    
    Server:
      Version:  1.4.3
      Revision: 269548fa27e0089a8b8278fc4fc781d7f65a939b
      UUID: b7e3b0e7-8a36-4105-a198-470da2be02f2

初始化Containerd配置：

containerd config default > /etc/containerd/config.toml
    systemctl enabled containerd
    systemctl start containerd

替换 containerd 默认的sand\_box镜像，编辑`/etc/containerd/config.toml`文件：

# registry.cn-hangzhou.aliyuncs.com/google-containers/pause-amd64:3.0 可以使用阿里云镜像源
    sandbox_image = "172.16.0.4/captain/pause-amd64:3.0"

应用配置并重新运行containerd服务

systemctl daemon-reload
    systemctl restart containerd

![ed7fcb0f75eb031f7dc37bc8fb062058.png][]

## 二、运行一个busybox镜像： ##

预先准备：

[root@containerd ~]# # 拉取镜像
    [root@containerd ~]# ctr -n k8s.io i pull docker.io/library/busybox:latest
    [root@containerd ~]# # 创建一个container(此时还未运行)
    [root@containerd ~]# ctr -n k8s.io container create docker.io/library/busybox:latest busybox
    [root@containerd ~]# # 创建一个task
    [root@containerd ~]# ctr -n k8s.io task start -d busybox
    [root@containerd ~]# # 上述步骤也可以简写成如下
    [root@containerd ~]# # ctr -n k8s.io run -d docker.io/library/busybox:latest busybox

查看该容器在宿主机的PID：

[root@containerd ~]# ctr -n k8s.io task ls
    TASK       PID     STATUS    
    busybox    2356    RUNNING
    [root@containerd ~]# ps ajxf|grep "containerd-shim-runc\|2356"|grep -v grep
         1   2336   2336   1178 ?            -1 Sl       0   0:00 /usr/bin/containerd-shim-runc-v2 -namespace k8s.io -id busybox -address /run/containerd/containerd.sock
      2336   2356   2356   2356 ?            -1 Ss       0   0:00  \_ sh

进入容器：

[root@containerd ~]# ctr -n k8s.io t exec --exec-id $RANDOM -t busybox sh
    / # uname -a
    Linux containerd 3.10.0-1062.el7.x86_64 #1 SMP Wed Aug 7 18:08:02 UTC 2019 x86_64 GNU/Linux
    / # ls /etc
    group      localtime  network    passwd     shadow
    / # ip a
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
    / #

发送SIGKILL信号量杀死该容器：

[root@containerd ~]# ctr -n k8s.io t kill -s SIGKILL busybox
    [root@containerd ~]# ctr -n k8s.io t rm busybox
    WARN[0000] task busybox exit with non-zero exit code 137

## 三、创建CNI网络 ##

访问如下两个Git项目，并从release页面下载最新版本:

<table> 
 <thead> 
  <tr> 
   <th>链接</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>containernetworking/plugins</td> 
   <td>CNI插件源码（本教程版本：v0.9.0）<br>文件名：cni-plugins-linux-amd64-v0.9.0.tgz</td> 
  </tr> 
  <tr> 
   <td>containernetworking/cni</td> 
   <td>CNI源码（本教程版本：v0.8.0）<br>文件名：cni-v0.8.0.tar.gz</td> 
  </tr> 
  <tr> 
   <td>https://www.cni.dev/plugins/</td> 
   <td>CNI插件列表介绍文档</td> 
  </tr> 
 </tbody> 
</table>

下载至HOME目录并解压：

[root@containerd ~]# pwd
    /root
    [root@containerd ~]# # 解压至HOME目录的cni-plugins/文件夹中
    [root@containerd ~]# mkdir -p cni-plugins
    [root@containerd ~]# tar xvf cni-plugins-linux-amd64-v0.9.0.tgz -C cni-plugins
    [root@containerd ~]# # 解压至HOME目录的cni/文件夹中
    [root@containerd ~]# tar -zxvf cni-v0.8.0.tar.gz
    [root@containerd ~]# mv cni-0.8.0 cni

本教程我们首先使用bridge插件创建一个网卡，首先执行如下指令：

mkdir -p /etc/cni/net.d
    cat >/etc/cni/net.d/10-mynet.conf <<EOF
    {
      "cniVersion": "0.2.0",
      "name": "mynet",
      "type": "bridge",
      "bridge": "cni0",
      "isGateway": true,
      "ipMasq": true,
      "ipam": {
        "type": "host-local",
        "subnet": "10.22.0.0/16",
        "routes": [
          { "dst": "0.0.0.0/0" }
        ]
      }
    }
    EOF
    
    
    cat >/etc/cni/net.d/99-loopback.conf <<EOF
    {
      "cniVersion": "0.2.0",
      "name": "lo",
      "type": "loopback"
    }
    EOF

随后激活网卡（说明：`宿主机执行ip a命令即可看到一个cni0的网卡`）：

[root@containerd ~]# cd cni/scripts/
    [root@containerd scripts]# CNI_PATH=/root/cni-plugins ./priv-net-run.sh echo "Hello World"
    Hello World
    [root@containerd scripts]# ip a
    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: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
        link/ether 00:0c:29:ea:35:42 brd ff:ff:ff:ff:ff:ff
        inet 192.168.105.110/24 brd 192.168.105.255 scope global noprefixroute ens33
           valid_lft forever preferred_lft forever
        inet6 fe80::1c94:5385:5133:cd48/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever
    10: cni0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
        link/ether de:12:0b:ea:a4:bc brd ff:ff:ff:ff:ff:ff
        inet 10.22.0.1/24 brd 10.22.0.255 scope global cni0
           valid_lft forever preferred_lft forever
        inet6 fe80::dc12:bff:feea:a4bc/64 scope link 
           valid_lft forever preferred_lft forever

## 四、使containerd容器具备网络功能 ##

注重细节的我们在步骤二中将会发现，busybox容器此刻仅有一张本地网卡，其是无法访问任何网络的，那么我们如何使其具备各容器互通、外部网络通信功能呢？不妨执行如下指令：

[root@containerd ~]# ctr -n k8s.io t ls
    TASK       PID     STATUS    
    busybox    5111    RUNNING
    [root@containerd ~]# # pid=5111
    [root@containerd ~]# pid=$(ctr -n k8s.io t ls|grep busybox|awk '{print $2}')
    [root@containerd ~]# netnspath=/proc/$pid/ns/net
    [root@containerd ~]# CNI_PATH=/root/cni-plugins /root/cni/scripts/exec-plugins.sh add $pid $netnspath

随后进入busybox容器我们将会发现其新增了一张网卡并可以实现外部网络访问：

[root@containerd ~]# ctr -n k8s.io task exec --exec-id $RANDOM -t busybox  sh -
    / # ip a
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue 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
    3: eth0@if12: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue 
        link/ether d2:f2:8d:53:fc:95 brd ff:ff:ff:ff:ff:ff
        inet 10.22.0.13/24 brd 10.22.0.255 scope global eth0
           valid_lft forever preferred_lft forever
        inet6 fe80::d0f2:8dff:fe53:fc95/64 scope link 
           valid_lft forever preferred_lft forever
    / # ping 114.114.114.114
    PING 114.114.114.114 (114.114.114.114): 56 data bytes
    64 bytes from 114.114.114.114: seq=0 ttl=127 time=17.264 ms
    64 bytes from 114.114.114.114: seq=0 ttl=127 time=13.838 ms
    64 bytes from 114.114.114.114: seq=1 ttl=127 time=18.024 ms
    64 bytes from 114.114.114.114: seq=2 ttl=127 time=15.316 ms

小试牛刀：按照上述方法分别创建两个名为busybox-1与busybox-2容器，借助nc -l -p 8080暴露TCP服务端口进行彼此通信。

![f7d7b1d7b021081fc7530a3bb65741f0.png][]

## 五、与宿主机共享目录 ##

通过执行如下方案，我们即可实现容器与宿主机的/tmp进行共享：

[root@docker scripts]# ctr -n k8s.io c create v4ehxdz8.mirror.aliyuncs.com/library/busybox:latest busybox1 --mount type=bind,src=/tmp,dst=/host,options=rbind:rw
    [root@docker scripts]# ctr -n k8s.io t start -d busybox1 bash
    [root@docker scripts]# ctr -n k8s.io t exec -t --exec-id $RANDOM busybox1 sh
    / # echo "Hello world" > /host/1 
    / # 
    [root@docker scripts]# cat /tmp/1 
    Hello world

## 六、与其它容器共享ns ##

本节仅对pid ns共享进行举例，其它ns共享与该方案类似

首先我们对docker的ns共享进行实验：

[root@docker scripts]# docker run --rm -it -d busybox sh
    687c80243ee15e0a2171027260e249400feeeee2607f88d1f029cc270402cdd1
    [root@docker scripts]# docker run --rm -it -d --pid="container:687c80243ee15e0a2171027260e249400feeeee2607f88d1f029cc270402cdd1" busybox cat
    fa2c09bd9c042128ebb2256685ce20e265f4c06da6d9406bc357d149af7b83d2
    [root@docker scripts]# docker ps -a
    CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
    fa2c09bd9c04        busybox             "cat"               2 seconds ago       Up 1 second                             pedantic_goodall
    687c80243ee1        busybox             "sh"                22 seconds ago      Up 21 seconds                           hopeful_franklin
    [root@docker scripts]# docker exec -it 687c80243ee1 sh
    / # ps aux
    PID   USER     TIME  COMMAND
        1 root      0:00 sh
        8 root      0:00 cat
       15 root      0:00 sh
       22 root      0:00 ps aux

接下来仿照该方案我们基于containerd的方式实现pid ns共享：

[root@docker scripts]# ctr -n k8s.io t ls
    TASK        PID     STATUS    
    busybox     2255    RUNNING
    busybox1    2652    RUNNING
    [root@docker scripts]# # 这里的2652即为已有task运行时的pid号
    [root@docker scripts]# ctr -n k8s.io c create --with-ns "pid:/proc/2652/ns/pid" v4ehxdz8.mirror.aliyuncs.com/library/python:3.6-slim python
    [root@docker scripts]# ctr -n k8s.io t start -d python python  # 这里启动了一个python的命令
    [root@docker scripts]# ctr -n k8s.io t exec -t --exec-id $RANDOM busybox1 sh
    / # ps aux
    PID   USER     TIME  COMMAND
        1 root      0:00 sh
       34 root      0:00 python3
       41 root      0:00 sh
       47 root      0:00 ps aux

## 七、docker/containerd并用 ##

参考链接：https://docs.docker.com/engine/reference/commandline/dockerd/  
在完成对containerd的安装/配置启动后，我们可以在宿主机中安装docker客户端及服务。执行如下指令：

yum install -y yum-utils device-mapper-persistent-data lvm2
    yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
    yum update -y && yum install -y docker-ce-18.06.2.ce
    systemctl enable docker

编辑`/etc/systemd/system/multi-user.target.wants/docker.service`文件并为其新增`--containerd`启动项：

![7a1567f7ebdb67e6d5371d666d5d203c.png][]

保存，推出后执行如下指令：

[root@docker ~]# systemctl daemon-reload
    [root@docker ~]# systemctl start docker
    [root@docker ~]# ps aux|grep docker
    root      72570  5.0  2.9 872668 55216 ?        Ssl  01:31   0:00 /usr/bin/dockerd --containerd /run/containerd/containerd.sock --debug

进行验证：

![8b344d9bd9d2aee119b11c67c0b532ad.png][]

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