Docker基本用法

什么是docker

docker中的容器：

lxc --> libcontainer --> runC

OCI和OCF

OCI

Open Container-initiative

• 由Linux基金会主导于2015年6月创立
• 旨在围绕容器格式和运行时制定一个开放的工业化标准
• 包含两个规范
  • the Runtime Specification（runtime-spec）（运行规范）
  • the Image Specification（image-spec）（镜像规范）

OCF

Open Container Format（打开容器格式）

runC是一个CLI工具，用于根据OCI规范生成和运行容器

• 容器作为runC的子进程启动，可以嵌入到各种其他系统中，而不需要运行守护进程
• runC是基于libcontainer构建的，同样的容器技术为数百万的Docker引擎安装提供了动力

docker提供了一个专门容纳容器镜像的站点：https://hub.docker.com

Docker架构

现实工作中Client客户端和Docker_HOST服务端是在一台主机上的，是不会使用本地docker管理其他主机上的容器的。

Registry：这个是容器仓库，里面放着各种软件的容器仓库，软件容器仓库中又放着各种版本的镜像文件

镜像是静态的，而容器是动态的，容器有其生命周期，镜像与容器的关系类似于程序与进程的关系。镜像类似于文件系统中的程序文件，而容器则类似于将一个程序运行起来的状态，也即进程。所以容器是可以删除的，容器被删除后其镜像是不会被删除的。

docker对象

当你使用Docker容器时，你可以创建和使用图像、容器、网络、卷、插件和其他对象

• IMAGES(镜像)

  • 镜像是一个只读的，用来创建容器的模板
  • 通常，一个镜像是基于另外一个镜像的做的，加上一些自定义的操作
  • 您可以创建自己的映像，也可以只使用其他人创建并在注册表中发布在官网仓库中的镜像

• CONTAINERS(容器)

  • 一个容器时一个镜像运行起来生成的
  • 您可以通过docker AP(一种接口)I或CLI(命令行功能)创建、运行、停止、移动或删除容器
  • 你可以将容器连接到一个或多个网络，附加存储到里面，就是将容器的数据挂载到那个存储中不放在本地。基于当前的状态创建一个新镜像，这里的状态是指安装了某一个服务的情况

Docker的安装和使用

//下载docker源
[root@localhost yum.repos.d]# curl -o docker-ce.repo https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/docker-ce.repo
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1919  100  1919    0     0   1626      0  0:00:01  0:00:01 --:--:--  1626

//修改repo文件，把地址改为国内
[root@localhost yum.repos.d]# sed -i 's@https://download.docker.com@https://mirrors.tuna.tsinghua.edu.cn/docker-ce@g' docker-ce.repo

//安装docker
[root@localhost ~]# yum -y install docker-ce

docker加速

docker-ce的配置文件是/etc/docker/daemon.json，此文件默认不存在，需要我们手动创建并进行配置，而docker的加速就是通过配置此文件来实现的。

//启动docker
//启动docker后会自动生成/etc/docker目录
[root@localhost ~]# systemctl enable --now docker
Created symlink /etc/systemd/system/multi-user.target.wants/docker.service → /usr/lib/systemd/system/docker.service.
[root@localhost ~]# ll /etc/docker/
总用量 4
-rw-------. 1 root root 244 12月  2 12:14 key.json

//配置阿里云加速器
[root@localhost ~]# tee /etc/docker/daemon.json <<-'EOF'
> {
>   "registry-mirrors": ["https://j7nfsalu.mirror.aliyuncs.com"]
> }
> EOF
{
  "registry-mirrors": ["https://j7nfsalu.mirror.aliyuncs.com"]
}
[root@localhost ~]# systemctl daemon-reload
[root@localhost ~]# systemctl restart docker

//查看docker信息
[root@localhost ~]# docker info
Client:
 Context:    default
 Debug Mode: false		//开发模式
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Build with BuildKit (Docker Inc., v0.6.3-docker)
  scan: Docker Scan (Docker Inc., v0.9.0)

Server:
 Containers: 0
  Running: 0		//运行的容器
  Paused: 0		//暂停的容器
  Stopped: 0		//停止的容器
 Images: 0		//已有的镜像
 Server Version: 20.10.11
 Storage Driver: overlay2
  Backing Filesystem: xfs		//储存文件类型
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 1
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runtime.v1.linux runc io.containerd.runc.v2
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7b11cfaabd73bb80907dd23182b9347b4245eb5d
 runc version: v1.0.2-0-g52b36a2
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 4.18.0-305.3.1.el8.x86_64
 Operating System: CentOS Linux 8
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 1.748GiB
 Name: localhost
 ID: 6ZZS:6J2I:UR4R:BD3B:UIRQ:GYNP:TPKN:VFQI:NBJ5:U6EV:TNBK:O45Y
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Registry Mirrors:			//加速地址
  https://j7nfsalu.mirror.aliyuncs.com/
 Live Restore Enabled: false

Docker常用操作

命令	功能
docker search	Search the Docker Hub for images（在docker hub官网上搜索镜像）
docker pull	Pull an image or a repository from a registry(从registry也就是官网拉取一个镜像到本地来)
docker images	List images (列出本地镜像)
docker create	Create a new conntainer (创建一个容器，镜像可以是本地的也可以是网络上的)
docker start	Start one or more stopped containers(启动容器)
docker run	Run a command in a new container(创建一个容器，并且创建后就自动启动)
docker attach	Attach to a runninng container (附加到容器，并让容器在前台运行，但是不能做任何操作)
docker ps	List containers(查看此时正在运行的容器)
docker logs	Fetch the logs of a container (查看容器的日志)
docker restart	Restart a container(重启容器)
docker stop	Stop one or more running containers (停止容器 -15)
docker kill	Kill one or more running containers(强制杀死容器) -9
docker rm	Remove onne or more containers (删除容器)
docker exec	Run a command in a running container (进入到容器，)
docker info	Display system-wide information(查看docker的信息)
docker inspect	Return low-level information on Docker objects(显示容器的详细信息)

• docker search

[root@localhost ~]# docker search nginx
NAME                              DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
nginx                             Official build of Nginx.                        15899     [OK]       
jwilder/nginx-proxy               Automated Nginx reverse proxy for docker con…   2098                 [OK]
richarvey/nginx-php-fpm           Container running Nginx + PHP-FPM capable of…   820                  [OK]
jc21/nginx-proxy-manager          Docker container for managing Nginx proxy ho…   285                  
linuxserver/nginx                 An Nginx container, brought to you by LinuxS…   160                  

#STARS受欢迎程度   OFFICIAL官方提供

• docker pull
  从官网拉取一个镜像，如果不指定版本号，那么就拉取最新版本的

[root@localhost ~]# docker pull nginx
Using default tag: latest
latest: Pulling from library/nginx
eff15d958d66: Pull complete 
1e5351450a59: Pull complete 
2df63e6ce2be: Pull complete 
9171c7ae368c: Pull complete 
020f975acd28: Pull complete 
266f639b35ad: Pull complete 
Digest: sha256:097c3a0913d7e3a5b01b6c685a60c03632fc7a2b50bc8e35bcaa3691d788226e
Status: Downloaded newer image for nginx:latest
docker.io/library/nginx:latest

• docker images
  列出本地的镜像

[root@localhost ~]# docker images
REPOSITORY   TAG       IMAGE ID       CREATED       SIZE
nginx        latest    ea335eea17ab   2 weeks ago   141MB

• docker create
  创建一个容器，如果本地没有镜像就从网上拉取

//本地镜像创建容器
[root@localhost ~]# docker create nginx
c34e7daf645fda6ff440ae9d9dd2b8ed78f4d7756b473ca5226d12e79350a24a

//从网络上拉取镜像创建容器
[root@localhost ~]# docker create busybox
Unable to find image 'busybox:latest' locally
latest: Pulling from library/busybox
3aab638df1a9: Pull complete 
Digest: sha256:52817dece4cfe26f581c834d27a8e1bcc82194f914afe6d50afad5a101234ef1
Status: Downloaded newer image for busybox:latest
a85316c6c0f9adb5102230be80fb2df12869c6d495523d39098a1d342c050457

• docker start
  启动容器

//列出所有容器
[root@localhost ~]# docker ps -a
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS    PORTS     NAMES
a85316c6c0f9   busybox   "sh"                     2 minutes ago   Created             relaxed_hamilton
c34e7daf645f   nginx     "/docker-entrypoint.…"   3 minutes ago   Created             wonderful_stonebraker

[root@localhost ~]# docker start c34e7daf645f
c34e7daf645f

[root@localhost ~]# docker ps 		//列出正在运行的容器
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS     NAMES
c34e7daf645f   nginx     "/docker-entrypoint.…"   3 minutes ago   Up 4 seconds   80/tcp    wonderful_stonebraker

• docker restart
  重新启动容器

[root@localhost ~]# docker restart c34e7daf645f
c34e7daf645f
[root@localhost ~]# docker ps 
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS     NAMES
c34e7daf645f   nginx     "/docker-entrypoint.…"   5 minutes ago   Up 2 seconds   80/tcp    wonderful_stonebraker

• docker attach
  让容器在前台运行，此时是不能做任何操作的，如果这个时候退出则服务也会退出停止

[root@localhost ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS              PORTS     NAMES
c34e7daf645f   nginx     "/docker-entrypoint.…"   6 minutes ago   Up About a minute   80/tcp    wonderful_stonebraker

[root@localhost ~]# docker attach c34e7daf645f
^C2021/12/02 05:37:21 [notice] 1#1: signal 2 (SIGINT) received, exiting
Ctrl+c退出

• docker run

[root@localhost ~]# docker run -it busybox /bin/sh
/ # ls
bin   dev   etc   home  proc  root  sys   tmp   usr   var
/ # exit

• docker rm
  删除容器，需要注意的是删除容器只能删除不在运行的，如果容器在运行需要先停止再删除，或者docker rm -f 强制删除

[root@localhost ~]# docker ps -a
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS                     PORTS     NAMES
6a0576257504   busybox   "/bin/sh"                2 minutes ago    Exited (0) 2 minutes ago             confident_spence
a85316c6c0f9   busybox   "sh"                     9 minutes ago    Created                              relaxed_hamilton
c34e7daf645f   nginx     "/docker-entrypoint.…"   10 minutes ago   Exited (0) 3 minutes ago             wonderful_stonebraker

[root@localhost ~]# docker rm 6a0576257504
6a0576257504
[root@localhost ~]# docker ps -a
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS                     PORTS     NAMES
a85316c6c0f9   busybox   "sh"                     9 minutes ago    Created                              relaxed_hamilton
c34e7daf645f   nginx     "/docker-entrypoint.…"   10 minutes ago   Exited (0) 3 minutes ago             wonderful_stonebraker

• docker inspect
  查看容器详细信息

[root@localhost ~]# docker inspect c34e7daf645f
[
    {
        "Id": "c34e7daf645fda6ff440ae9d9dd2b8ed78f4d7756b473ca5226d12e79350a24a",
        "Created": "2021-12-02T05:30:16.469655359Z",
        "Path": "/docker-entrypoint.sh",
        "Args": [
            "nginx",
            "-g",
            "daemon off;"
        ],
......
"Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:02",
                    "DriverOpts": null
                }
            }

• docker logs
  查看容器的日志文件

[root@localhost ~]# docker logs c34e7daf645f
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2021/12/02 05:33:42 [notice] 1#1: using the "epoll" event method
2021/12/02 05:33:42 [notice] 1#1: nginx/1.21.4
2021/12/02 05:33:42 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 
2021/12/02 05:33:42 [notice] 1#1: OS: Linux 4.18.0-305.3.1.el8.x86_64
2021/12/02 05:33:42 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576

• exec
  进入到容器中（最常用），退出也不会停止运行

[root@localhost ~]# docker exec -it c34e7daf645f /bin/bash
root@c34e7daf645f:/# ls
bin   dev                  docker-entrypoint.sh  home  lib64  mnt  proc  run   srv  tmp  var
boot  docker-entrypoint.d  etc                   lib   media  opt  root  sbin  sys  usr
root@c34e7daf645f:/# exit
exit