Docker安装和基础用法实例分析
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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:
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:
1.2 docker 到目前(2016/09/16)为止的版本历史
2. docker 的基本操作
2.1 docker 容器的状态机
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 ? 00:00:00 python app.py root@devstack:/home/sammy# docker logs newweb31 #获取容器的日志 * running on http://0.0.0.0:5000/ (press ctrl+c to quit) root@devstack:/home/sammy# docker stop newweb31 #停止容器 newweb31 root@devstack:/home/sammy# docker inspect --format='{{.state.status}}' newweb31 exited root@devstack:/home/sammy# docker rm newweb31 #删除容器 newweb31 root@devstack:/home/sammy# docker inspect --format='{{.state.status}}' newweb31 error: no such image, container or task: newweb31
(2) docker stop 和 docker kill
在docker stop 命令执行的时候,会先向容器中pid为1的进程发送系统信号 sigterm,然后等待容器中的应用程序终止执行,如果等待时间达到设定的超时时间(默认为 10秒,用户可以指定特定超时时长),会继续发送sigkill的系统信号强行kill掉进程。在容器中的应用程序,可以选择忽略和不处理sigterm信号,不过一旦达到超时时间,程序就会被系统强行kill掉,因为sigkill信号是直接发往系统内核的,应用程序没有机会去处理它。
比如运行 docker stop web5 -t 20 命令后:
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:
首先 docker 向容器发出 sigterm 信号(signal=15)
等待20秒 (01:18 到 01:38)
再发送 sigkill 系统信号 (signal = 9)
然后容器被杀掉了 (die)
而 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:[: ]) --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 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
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