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

容器运行时Containerd基础_kubernetes

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:

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。

容器运行时Containerd基础_gwt_02

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
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：

容器运行时Containerd基础_docker_03容器运行时Containerd基础_gwt_04

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
[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：

容器运行时Containerd基础_docker_05容器运行时Containerd基础_trigger_06

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