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本系列文章将介绍Docker的有关知识:

(1)Docker 安装及基本用法

(2)Docker 镜像

(3)Docker 容器的隔离性 - 使用 Linux namespace 隔离容器的运行环境

(4)Docker 容器的隔离性 - 使用 cgroups 限制容器使用的资源

(5)Docker 网络

1. 安装

1.1 在 Ubuntu 14.04 上安装 Docker

前提要求:

内核版本必须是3.10或者以上

依次执行下面的步骤:

sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates
sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
编辑 /etc/apt/sources.list.d/docker.list 文件,添加 deb https://apt.dockerproject.org/repo ubuntu-trusty main
sudo apt-get update
sudo apt-get purge lxc-docker
apt-cache policy docker-engine
apt-get upgrade
sudo apt-get install linux-image-extra-$(uname -r) linux-image-extra-virtual
sudo apt-get install docker-engine

至此,安装过程完成。

运行 sudo service docker start 启动 Docker 守护进程。
运行 docker version 查看 Docker 版本

root@devstack:/home/sammy# docker --version
Docker version 1.12.1, build 23cf638


启动第一个容器:

1.启动第一个Docker 容器 docker run hello-world
root@devstack:/home/sammy# docker run hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.
它的运行成功也表明前面的安装步骤都运行正确了。

以上内容参考自 Docker 官网:https://docs.docker.com/engine/installation/linux/ubuntulinux/

1.2 Docker 到目前(2016/09/16)为止的版本历史

版本号              发布日期      发布经理
Docker 1.12.1  08/18/2016 
Docker 1.12.0  07/28/2016 
Docker 1.11.0  04/12/2016 @mlaventure
Docker 1.10.0  02/04/2016 @thaJeztah
Docker 1.9.0   10/29/2015  @tiborvass
Docker 1.8.0    08/11/2015 @calavera 

2. Docker 的基本操作

2.1 Docker 容器的状态机

Docker安装和基础用法 Docker入门教程第二篇

一个容器在某个时刻可能处于以下几种状态之一:

created:已经被创建 (使用 docker ps -a 命令可以列出)但是还没有被启动 (使用 docker ps 命令还无法列出)
running:运行中
paused:容器的进程被暂停了
restarting:容器的进程正在重启过程中
exited:上图中的 stopped 状态,表示容器之前运行过但是现在处于停止状态(要区别于 created 状态,它是指一个新创出的尚未运行过的容器)。可以通过 start 命令使其重新进入 running 状态
destroyed:容器被删除了,再也不存在了

你可以在 docker inspect 命令的输出中查看其详细状态:

"State": {
      "Status": "running",
      "Running": true,
      "Paused": false,
      "Restarting": false,
      "OOMKilled": false,
      "Dead": false,
      "Pid": 4597,
      "ExitCode": 0,
      "Error": "",
      "StartedAt": "2016-09-16T08:09:34.53403504Z",
      "FinishedAt": "2016-09-16T08:06:44.365106765Z"
    }

2.2 Docker 命令概述

我们可以把Docker 的命令大概地分类如下:

镜像操作:

    build     Build an image from a Dockerfile
    commit    Create a new image from a container's changes
    images    List images
    load      Load an image from a tar archive or STDIN
    pull      Pull an image or a repository from a registry
    push      Push an image or a repository to a registry
    rmi       Remove one or more images
    search    Search the Docker Hub for images
    tag       Tag an image into a repository
    save      Save one or more images to a tar archive (streamed to STDOUT by default)
    history   显示某镜像的历史
    inspect   获取镜像的详细信息

容器及其中应用的生命周期操作:

    create    Create a new container (创建一个容器)       
    kill      Kill one or more running containers
    inspect   Return low-level information on a container, image or task
    pause     Pause all processes within one or more containers
    ps        List containers
    rm        Remove one or more containers (删除一个或者多个容器)
    rename    Rename a container
    restart   Restart a container
    run       Run a command in a new container (创建并启动一个容器)
    start     Start one or more stopped containers (启动一个处于停止状态的容器)
    stats     Display a live stream of container(s) resource usage statistics (显示容器实时的资源消耗信息)
    stop      Stop one or more running containers (停止一个处于运行状态的容器)
    top       Display the running processes of a container
    unpause   Unpause all processes within one or more containers
    update    Update configuration of one or more containers
    wait      Block until a container stops, then print its exit code
    attach    Attach to a running container
    exec      Run a command in a running container
    port      List port mappings or a specific mapping for the container
    logs      获取容器的日志    

容器文件系统操作:

    cp        Copy files/folders between a container and the local filesystem
    diff      Inspect changes on a container's filesystem
    export    Export a container's filesystem as a tar archive
    import    Import the contents from a tarball to create a filesystem image

 Docker registry 操作:

    login     Log in to a Docker registry.
    logout    Log out from a Docker registry.

 Volume 操作

    volume    Manage Docker volumes    

网络操作

    network   Manage Docker networks

Swarm 相关操作

    swarm     Manage Docker Swarm
    service   Manage Docker services
    node      Manage Docker Swarm nodes       

系统操作:    

    version   Show the Docker version information
    events    Get real time events from the server  (持续返回docker 事件)
    info      Display system-wide information (显示Docker 主机系统范围内的信息)

比较有意思的几个命令:

(1)容器从生到死整个生命周期

root@devstack:/home/sammy# docker create --name web31 training/webapp python app.py #创建名字为 web31 的容器
7465f4cb7c49555af32929bd1bc4213f5e72643c0116450e495b71c7ec128502
root@devstack:/home/sammy# docker inspect --format='{{.State.Status}}' web31 #其状态为 created
created
root@devstack:/home/sammy# docker start web31 #启动容器
web31
root@devstack:/home/sammy# docker inspect --format='{{.State.Status}}' web31 #其状态为 running
running
root@devstack:/home/sammy# docker pause web31 #暂停容器
web31
root@devstack:/home/sammy# docker inspect --format='{{.State.Status}}' web31
paused
root@devstack:/home/sammy# docker unpause web31 #继续容器
web31
root@devstack:/home/sammy# docker inspect --format='{{.State.Status}}' web31
running
root@devstack:/home/sammy# docker rename web31 newweb31 #重命名
root@devstack:/home/sammy# docker inspect --format='{{.State.Status}}' newweb31
running
root@devstack:/home/sammy# docker top newweb31 #在容器中运行 top 命令
UID         PID         PPID        C          STIME        TTY         TIME        CMD
root        5009        4979        0          16:28        "htmlcode">
2016-09-16T16:01:18.206540853+08:00 container kill b3256ef1400a7f6a6f242e377a77af5e25d3b12237c4ee7c2e9b31a5f6437868 (image=training/webapp, name=web5, signal=15)
2016-09-16T16:01:38.212352224+08:00 container kill b3256ef1400a7f6a6f242e377a77af5e25d3b12237c4ee7c2e9b31a5f6437868 (image=training/webapp, name=web5, signal=9)
2016-09-16T16:01:38.235021315+08:00 container die b3256ef1400a7f6a6f242e377a77af5e25d3b12237c4ee7c2e9b31a5f6437868 (exitCode=137, image=training/webapp, name=web5)

能看到:

1.首先 docker 向容器发出 SIGTERM 信号(signal=15)
2.等待20秒 (01:18 到 01:38)
3.再发送 SIGKILL 系统信号 (signal = 9)
4.然后容器被杀掉了 (die)

docker kill 命令会直接发出SIGKILL的系统信号,以强行终止容器中程序的运行。运行 docker kill web5 命令后:

2016-09-16T16:06:44.351086471+08:00 container kill b3256ef1400a7f6a6f242e377a77af5e25d3b12237c4ee7c2e9b31a5f6437868 (image=training/webapp, name=web5, signal=9)
2016-09-16T16:06:44.365116100+08:00 container die b3256ef1400a7f6a6f242e377a77af5e25d3b12237c4ee7c2e9b31a5f6437868 (exitCode=137, image=training/webapp, name=web5)
可见直接发出的是 SIGKILL 信号,容器立马就被杀掉了。

(3)使用 docker cp 在 host 和 container 之间拷贝文件或者目录

root@devstack:/home/sammy# docker cp /home/sammy/mydockerbuild/Dockerfile web5:/webapp #从 host 拷贝文件到 container 里面
root@devstack:/home/sammy#
root@devstack:/home/sammy# docker cp web5:/webapp/Dockerfile /home/sammy/Dockerfile #从 container 里面拷贝文件到 host 上
root@devstack:/home/sammy# ls /home/sammy
chroot devstack Dockerfile mongodbdocker mydockerbuild webapp

(4)docker export 和 import

docker export:将一个容器的文件系统打包为一个压缩文件

root@devstack:/home/sammy# docker export web5 -o ./web5
root@devstack:/home/sammy# ls
chroot devstack Dockerfile mongodbdocker mydockerbuild web5 webapp

docker import:从一个压缩文件创建一个镜像

root@devstack:/home/sammy# docker import web5 web5img -m "imported on 0916"
sha256:745bb258be0a69a517367667646148bb2f662565bb3d222b50c0c22e5274a926
root@devstack:/home/sammy# docker history web5img
IMAGE        CREATED       CREATED BY     SIZE        COMMENT
745bb258be0a    6 seconds ago              324 MB       imported on 0916

 2.3 docker run 命令

docker run 命令会创建一个容器并启动它,它也是包含很多的参数,按照用途将它们分类如下:
   cgroups 和 namespace 相关:

   --blkio-weight value     Block IO (relative weight), between 10 and 1000
   --blkio-weight-device value  Block IO weight (relative device weight) (default [])
   --cgroup-parent string    Optional parent cgroup for the container
   --cpu-percent int       CPU percent (Windows only)
   --cpu-period int       Limit CPU CFS (Completely Fair Scheduler) period
   --cpu-quota int        Limit CPU CFS (Completely Fair Scheduler) quota
 -c, --cpu-shares int       CPU shares (relative weight)
   --cpuset-cpus string     CPUs in which to allow execution (0-3, 0,1)
   --cpuset-mems string     MEMs in which to allow execution (0-3, 0,1)
   --device-read-bps value    Limit read rate (bytes per second) from a device (default [])
   --device-read-iops value   Limit read rate (IO per second) from a device (default [])
   --device-write-bps value   Limit write rate (bytes per second) to a device (default [])
   --device-write-iops value   Limit write rate (IO per second) to a device (default [])
   --ipc string         IPC namespace to use
 -m, --memory string        Memory limit
   --memory-reservation string  Memory soft limit
   --memory-swap string     Swap limit equal to memory plus swap: '-1' to enable unlimited swap
   --memory-swappiness int    Tune container memory swappiness (0 to 100) (default -1)
   --kernel-memory string    Kernel memory limit
 -u, --user string         Username or UID (format: <name|uid>[:<group|gid>])
   --userns string        User namespace to use
   --uts string         UTS namespace to use
 -h, --hostname string       Container host name
   --pid string         PID namespace to use
   --pids-limit int       Tune container pids limit (set -1 for unlimited)
   --isolation string      Container isolation technology
   --io-maxbandwidth string   Maximum IO bandwidth limit for the system drive (Windows only)
   --io-maxiops uint       Maximum IOps limit for the system drive (Windows only)

linux process capabilities 相关参数:

   --cap-add value        Add Linux capabilities (default [])
   --cap-drop value       Drop Linux capabilities (default [])  

容器运行模式和环境相关:

 -d, --detach           Run container in background and print container ID
 -e, --env value          Set environment variables (default [])
 --env-file value       Read in a file of environment variables (default [])

DNS 相关:

   --dns value          Set custom DNS servers (default [])
   --dns-opt value        Set DNS options (default [])
   --dns-search value      Set custom DNS search domains (default [])


健康检查相关:

   --health-cmd string      Command to run to check health
   --health-interval duration  Time between running the check
   --health-retries int     Consecutive failures needed to report unhealthy
   --health-timeout duration   Maximum time to allow one check to run
   --no-healthcheck       Disable any container-specified HEALTHCHECK

IP 和端口:

   --ip string          Container IPv4 address (e.g. 172.30.100.104)
   --ip6 string         Container IPv6 address (e.g. 2001:db8::33)
 -p, --publish value        Publish a container's port(s) to the host (default [])
 -P, --publish-all         Publish all exposed ports to random ports
   --expose value        Expose a port or a range of ports (default [])
   --mac-address string     Container MAC address (e.g. 92:d0:c6:0a:29:33)
   --add-host value       Add a custom host-to-IP mapping (host:ip) (default [])

Volume 相关:

 -v, --volume value        Bind mount a volume (default [])
   --volume-driver string    Optional volume driver for the container
   --volumes-from value     Mount volumes from the specified container(s) (default [])
   --storage-opt value      Storage driver options for the container (default [])

Network 有关:

   --network string       Connect a container to a network (default "default")
   --network-alias value     Add network-scoped alias for the container (default [])
   --link value         Add link to another container (default [])
   --link-local-ip value     Container IPv4/IPv6 link-local addresses (default [])

日志有关:

   --log-driver string      Logging driver for the container
   --log-opt value        Log driver options (default [])
交互性有关:
 -a, --attach value        Attach to STDIN, STDOUT or STDERR (default [])
 -i, --interactive         Keep STDIN open even if not attached
  
  OOM 有关:  
   --oom-kill-disable      Disable OOM Killer
   --oom-score-adj int      Tune host's OOM preferences (-1000 to 1000)
  
  其它(待更进一步分类):
   --cidfile string       Write the container ID to the file
   --detach-keys string     Override the key sequence for detaching a container
   --device value        Add a host device to the container (default [])
   --disable-content-trust    Skip image verification (default true)
   --entrypoint string      Overwrite the default ENTRYPOINT of the image
   --group-add value       Add additional groups to join (default [])
   --help            Print usage
 -l, --label value         Set meta data on a container (default [])
   --label-file value      Read in a line delimited file of labels (default [])
   --name string         Assign a name to the container
   --privileged         Give extended privileges to this container
   --read-only          Mount the container's root filesystem as read only
   --restart string       Restart policy to apply when a container exits (default "no")
   --rm             Automatically remove the container when it exits
   --runtime string       Runtime to use for this container
   --security-opt value     Security Options (default [])
   --shm-size string       Size of /dev/shm, default value is 64MB
   --sig-proxy          Proxy received signals to the process (default true)
   --stop-signal string     Signal to stop a container, SIGTERM by default (default "SIGTERM")
   --sysctl value        Sysctl options (default map[])
   --tmpfs value         Mount a tmpfs directory (default [])
 -t, --tty             Allocate a pseudo-TTY
   --ulimit value        Ulimit options (default [])
 -w, --workdir string       Working directory inside the container

具体的内容以后会有专门文件分析。

3. Doker 平台的基本构成

Docker安装和基础用法 Docker入门教程第二篇

Docker 平台基本上由三部分组成:

客户端:用户使用 Docker 提供的工具(CLI 以及 API 等)来构建,上传镜像并发布命令来创建和启动容器
Docker 主机:从 Docker registry 上下载镜像并启动容器
Docker registry:Docker 镜像仓库,用于保存镜像,并提供镜像上传和下载
后面的文章会具体分析。

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。

标签:
Docker安装,Docker基础用法,Docker安装方法,Docker入门教程

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