Docker第二回（Docker的使用）

一、使用Docker的限制

1、要想使用linux容器，內核版本要高于3.8以上，并且至少在linux內核級要支持兩種技術，namespaces和CGroups。接著借助于在用戶空間組織一些工具，利用內核級所提供的這些技術， 從而實現容器運行的目的，Docker在容器運行使用簡化的道路上又近了一步，Docker提供了鏡像，而且是分層構建聯合掛載的方式，使得容器技術的使用更加被簡化。后來在Docker的主導下，又有了OCI和OCF標準。

OCI（Open Container Initiative）：由Linux基金會主導于2015年6月創立，OCI定義了容器運行時的標準，

OCI有兩部分組成：

                        the Runtime Specification：運行時標準

                        the image Specification：鏡像格式標準

OCF（Open Container Format）：runC是Docker按照開放容器格式標準（OCF）制定的一種具體實現，runC是從Docker的libcontainer中遷移而來的，實現了容器啟停，資源隔離等功能，Docker默認提供了docker-runc實現。

二、Docker的鏡像

默認Docker的鏡像是集中放置在Docker Hub上的，docker在創建容器時，Docker會先檢查本地是否有鏡像，如果沒有會到docker hub上去下載指定的鏡像到本地，并且下載下來的鏡像在容器使用結束后不會刪除，鏡像是不可修改的，只能重構。下面是docker的整體架構

三、Docker的安裝及使用

3.1、依賴及基礎環境：

                        1、64 bits CPU

                        2、Linux Kernel 3.10+

                        3、 Linux Kernel  cgroups and namespaces

3.2、centos 7安裝方式

1、extras repository；默認centos7的yum倉庫extras就有docker，版本比較老，下載新版本的docker的yum倉庫

[root@MiWiFi-R3L-srv ~]# cd /etc/yum.repos.d/
[root@MiWiFi-R3L-srv yum.repos.d]# wget https://mirrors.tuna.tsinghua.edu.cn/docker-ce/linux/centos/docker-ce.repo
[root@MiWiFi-R3L-srv yum.repos.d]# sed -i 's#https://download.docker.com#https://mirrors.tuna.tsinghua.edu.cn/docker-ce#g' docker-ce.repo
[root@MiWiFi-R3L-srv yum.repos.d]# yum update
[root@MiWiFi-R3L-srv yum.repos.d]# yum install docker-ce

2、docker-ce的配置文件;需要手動創建

[root@MiWiFi-R3L-srv yum.repos.d]# mkdir /etc/docker/
[root@MiWiFi-R3L-srv docker]# echo -e '{\n\t"registry-mirrors": ["https://registry.docker-cn.com"]\n}' >/etc/docker/daemon.json
[root@MiWiFi-R3L-srv docker]# systemctl start docker.service
[root@MiWiFi-R3L-srv docker]# docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 18.06.1-ce
Storage Driver: overlay2                                                         # docker要實現分層構建，聯合掛載。必須使用這種文件系統來支持。在centos7.4以前用的是device mapper，這種是lvm的實現，在docker上性能極差，還不穩定，已經廢棄。
......
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在能看到上面的一系列信息，說明docker已經安裝成功并可以使用了

3、docker 倉庫格式

[root@MiWiFi-R3L-srv docker]# docker search nginx
NAME                                                   DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
nginx                                                  Official build of Nginx.                        10034               [OK]                
jwilder/nginx-proxy                                    Automated Nginx reverse proxy for docker con??  1440                                    [OK]
richarvey/nginx-php-fpm                                Container running Nginx + PHP-FPM capable of??  633                                     [OK]
jrcs/letsencrypt-nginx-proxy-companion                 LetsEncrypt container to use with nginx as p??  428                                     [OK]
kong                                                   Open-source Microservice & API Management la??  237                 [OK]                
webdevops/php-nginx                                    Nginx with PHP-FPM                              117                                     [OK]
kitematic/hello-world-nginx                            A light-weight nginx container that demonstr??  112                                     
zabbix/zabbix-web-nginx-mysql                          Zabbix frontend based on Nginx web-server wi??  74                                      [OK]
bitnami/nginx                                          Bitnami nginx Docker Image                      58                                      [OK]
1and1internet/ubuntu-16-nginx-php-phpmyadmin-mysql-5   ubuntu-16-nginx-php-phpmyadmin-mysql-5          48                                      [OK]
linuxserver/nginx                                      An Nginx container, brought to you by LinuxS??  42                                      
tobi312/rpi-nginx                                      NGINX on Raspberry Pi / armhf                   23                                      [OK]
blacklabelops/nginx                                    Dockerized Nginx Reverse Proxy Server.          12                                      [OK]
wodby/drupal-nginx                                     Nginx for Drupal container image                11                                      [OK]
centos/nginx-18-centos7                                Platform for running nginx 1.8 or building n??  8                                       
webdevops/nginx                                        Nginx container                                 8                                       [OK]
nginxdemos/hello                                       NGINX webserver that serves a simple page co??  8                                       [OK]
centos/nginx-112-centos7                               Platform for running nginx 1.12 or building ??  5                                       
1science/nginx                                         Nginx Docker images that include Consul Temp??  4                                       [OK]
travix/nginx                                           NGinx reverse proxy                             2                                       [OK]
mailu/nginx                                            Mailu nginx frontend                            2                                       [OK]
pebbletech/nginx-proxy                                 nginx-proxy sets up a container running ngin??  2                                       [OK]
toccoag/openshift-nginx                                Nginx reverse proxy for Nice running on same??  1                                       [OK]
ansibleplaybookbundle/nginx-apb                        An APB to deploy NGINX                          0                                       [OK]
wodby/nginx                                            Generic nginx                                   0                                       [OK]

上面列表中，沒有/分隔開的倉庫是頂級倉庫，一般是docker hub官方的。帶/分隔開的是個人用戶創建的鏡像

4、啟動一個docker鏡像

docker run命令啟動容器時會先在本地倉庫查找鏡像，如果沒有在去docker hub倉庫中下載鏡像并啟動

[root@MiWiFi-R3L-srv docker]# docker container run --name nginx1 -d nginx:stable
Unable to find image 'nginx:stable' locally                                             # 說明本地倉庫中沒有nginx:stable鏡像
stable: Pulling from library/nginx
f17d81b4b692: Pull complete 
3df1ab0a1750: Pull complete 
576b56a453df: Pull complete 
Digest: sha256:8b600a4d029481cc5b459f1380b30ff6cb98e27544fc02370de836e397e34030
Status: Downloaded newer image for nginx:stable                                         # 從docker hub倉庫中下載nginx:stable鏡像成功
d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1 
[root@MiWiFi-R3L-srv docker]# docker container ls                                       # 查看正在運行的容器，發現nginx:stable已經正常運行
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
d5eb28ecbc5c        nginx:stable        "nginx -g 'daemon of??   4 minutes ago       Up 4 minutes        80/tcp              nginx1

查看正在運行的容器詳細信息

[root@MiWiFi-R3L-srv docker]# docker container inspect nginx1
[
    {
        "Id": "d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1",
        "Created": "2018-10-31T13:45:39.761183953Z",
        "Path": "nginx",
        "Args": [
            "-g",
            "daemon off;"
        ],
        "State": {
            "Status": "running",
            "Running": true,
            "Paused": false,
            "Restarting": false,
            "OOMKilled": false,
            "Dead": false,
            "Pid": 30605,
            "ExitCode": 0,
            "Error": "",
            "StartedAt": "2018-10-31T13:45:40.064902138Z",
            "FinishedAt": "0001-01-01T00:00:00Z"
        },
        "Image": "sha256:ecc98fc2f376d6560311b66d6958e4350a5a485ee07aa2d1235842d0bce440da",
        "ResolvConfPath": "/var/lib/docker/containers/d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1/resolv.conf",
        "HostnamePath": "/var/lib/docker/containers/d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1/hostname",
        "HostsPath": "/var/lib/docker/containers/d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1/hosts",
        "LogPath": "/var/lib/docker/containers/d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1/d5eb28ecbc5cbe86fb430c4098361b7199c9147e79c06096868746dc638ebec1-json.log",
        "Name": "/nginx1",
        "RestartCount": 0,
        "Driver": "overlay2",
        "Platform": "linux",
        "MountLabel": "",
        "ProcessLabel": "",
        "AppArmorProfile": "",
        "ExecIDs": null,
        "HostConfig": {
            "Binds": null,
            "ContainerIDFile": "",
            "LogConfig": {
                "Type": "json-file",
                "Config": {}
            },
            "NetworkMode": "default",
            "PortBindings": {},
            "RestartPolicy": {
                "Name": "no",
                "MaximumRetryCount": 0
            },
            "AutoRemove": false,
            "VolumeDriver": "",
            "VolumesFrom": null,
            "CapAdd": null,
            "CapDrop": null,
            "Dns": [],
            "DnsOptions": [],
            "DnsSearch": [],
            "ExtraHosts": null,
            "GroupAdd": null,
            "IpcMode": "shareable",
            "Cgroup": "",
            "Links": null,
            "OomScoreAdj": 0,
            "PidMode": "",
            "Privileged": false,
            "PublishAllPorts": false,
            "ReadonlyRootfs": false,
            "SecurityOpt": null,
            "UTSMode": "",
            "UsernsMode": "",
            "ShmSize": 67108864,
            "Runtime": "runc",
            "ConsoleSize": [
                0,
                0
            ],
            "Isolation": "",
            "CpuShares": 0,
            "Memory": 0,
            "NanoCpus": 0,
            "CgroupParent": "",
            "BlkioWeight": 0,
            "BlkioWeightDevice": [],
            "BlkioDeviceReadBps": null,
            "BlkioDeviceWriteBps": null,
            "BlkioDeviceReadIOps": null,
            "BlkioDeviceWriteIOps": null,
            "CpuPeriod": 0,
            "CpuQuota": 0,
            "CpuRealtimePeriod": 0,
            "CpuRealtimeRuntime": 0,
            "CpusetCpus": "",
            "CpusetMems": "",
            "Devices": [],
            "DeviceCgroupRules": null,
            "DiskQuota": 0,
            "KernelMemory": 0,
            "MemoryReservation": 0,
            "MemorySwap": 0,
            "MemorySwappiness": null,
            "OomKillDisable": false,
            "PidsLimit": 0,
            "Ulimits": null,
            "CpuCount": 0,
            "CpuPercent": 0,
            "IOMaximumIOps": 0,
            "IOMaximumBandwidth": 0,
            "MaskedPaths": [
                "/proc/acpi",
                "/proc/kcore",
                "/proc/keys",
                "/proc/latency_stats",
                "/proc/timer_list",
                "/proc/timer_stats",
                "/proc/sched_debug",
                "/proc/scsi",
                "/sys/firmware"
            ],
            "ReadonlyPaths": [
                "/proc/asound",
                "/proc/bus",
                "/proc/fs",
                "/proc/irq",
                "/proc/sys",
                "/proc/sysrq-trigger"
            ]
        },
        "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/99e98bcb3268cca54fb9964a69452a424e9de607df50ef6ce1631da4be9f203b-init/diff:/var/lib/docker/overlay2/30039edd43cad0ec36a0fb2e546da0b33bb38336d2fa548e2cfca11a382b1ecb/diff:/var/lib/docker/overlay2/3e588e0ac8a29338bf759041cee08eff0bc955e47f7f32b0fe65c6536cb83a2b/diff:/var/lib/docker/overlay2/c80f5826b0afb09f3cd5ff12fa5a16e67aa2aaed0ae7ea0b36aeffc218559abd/diff",
                "MergedDir": "/var/lib/docker/overlay2/99e98bcb3268cca54fb9964a69452a424e9de607df50ef6ce1631da4be9f203b/merged",
                "UpperDir": "/var/lib/docker/overlay2/99e98bcb3268cca54fb9964a69452a424e9de607df50ef6ce1631da4be9f203b/diff",
                "WorkDir": "/var/lib/docker/overlay2/99e98bcb3268cca54fb9964a69452a424e9de607df50ef6ce1631da4be9f203b/work"
            },
            "Name": "overlay2"
        },
        "Mounts": [],
        "Config": {
            "Hostname": "d5eb28ecbc5c",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "ExposedPorts": {
                "80/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "NGINX_VERSION=1.14.0-1~stretch",
                "NJS_VERSION=1.14.0.0.2.0-1~stretch"
            ],
            "Cmd": [
                "nginx",
                "-g",
                "daemon off;"
            ],
            "ArgsEscaped": true,
            "Image": "nginx:stable",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "maintainer": "NGINX Docker Maintainers <docker-maint@nginx.com>"
            },
            "StopSignal": "SIGTERM"
        },
        "NetworkSettings": {
            "Bridge": "",
            "SandboxID": "045cba9e5a6f39424dfb35c57d0ca43c9e335004d76c3dda36552aac740e014f",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {
                "80/tcp": null
            },
            "SandboxKey": "/var/run/docker/netns/045cba9e5a6f",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "3c28fb379c1c2018d05ae03ff163aae9a0c5c12621282e0d98f803daadaf97a6",
            "Gateway": "172.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "172.17.0.2",
            "IPPrefixLen": 16,
            "IPv6Gateway": "",
            "MacAddress": "02:42:ac:11:00:02",
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "NetworkID": "0a0cc62c3f1fba5667917f833b002ad0f5c1342acb61ff67317e17544e7a7ea1",
                    "EndpointID": "3c28fb379c1c2018d05ae03ff163aae9a0c5c12621282e0d98f803daadaf97a6",
                    "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
                }
            }
        }
    }
]

IPAddress是當前容器監聽的網絡地址，下面嘗試訪問nginx

[root@MiWiFi-R3L-srv docker]# curl 172.17.0.2
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h2>Welcome to nginx!</h2>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

5、停止一個容器

[root@MiWiFi-R3L-srv docker]# docker container stop nginx1                   # 停止一個運行中的容器，kill相當于 kill -9 ，stop相當于kill -15
nginx1
[root@MiWiFi-R3L-srv docker]# docker container ls                            # ls 只能看到正在運行中的容器
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
[root@MiWiFi-R3L-srv docker]# docker container ls -a                         # ls -a 可以看到停止狀態的容器
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
d5eb28ecbc5c        nginx:stable        "nginx -g 'daemon of??   11 minutes ago      Exited (0) 10 seconds ago                       nginx1

6、啟動一個停止的容器

[root@MiWiFi-R3L-srv docker]# docker container start nginx1
nginx1
[root@MiWiFi-R3L-srv docker]# docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
d5eb28ecbc5c        nginx:stable        "nginx -g 'daemon of??   14 minutes ago      Up 3 seconds        80/tcp              nginx1

7、暫停/取消暫停一個運行中的容器

[root@MiWiFi-R3L-srv docker]# docker container pause nginx1            # 暫停一個nginx容器
nginx1

[root@MiWiFi-R3L-srv docker]# docker container ls                      # 可以看到nginx的容器現在處于Paused狀態
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                       PORTS               NAMES
d5eb28ecbc5c        nginx:stable        "nginx -g 'daemon of??   15 minutes ago      Up About a minute (Paused)   80/tcp              nginx1
[root@MiWiFi-R3L-srv docker]# 

[root@MiWiFi-R3L-srv docker]# docker container unpause nginx1          # 取消一個容器的暫停狀態
nginx1
[root@MiWiFi-R3L-srv docker]# docker container ls                      # nginx容器的狀態又恢復運行
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
d5eb28ecbc5c        nginx:stable        "nginx -g 'daemon of??   16 minutes ago      Up About a minute   80/tcp              nginx1

8、在容器中執行交互命令

[root@MiWiFi-R3L-srv docker]# docker container exec -it redis1 /bin/sh

/data # ps

PID   USER     TIME  COMMAND

    1 redis     0:00 redis-server

   25 root      0:00 /bin/sh

   29 root      0:00 ps

9、在終端查看容器中進程的日志

[root@MiWiFi-R3L-srv docker]# docker container logs nginx1
172.17.0.1 - - [31/Oct/2018:13:54:40 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.29.0" "-"
172.17.0.1 - - [31/Oct/2018:14:02:19 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.29.0" "-"
172.17.0.1 - - [31/Oct/2018:14:14:17 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.29.0" "-"

四、docker容器的狀態轉換和各常用命令