Docker（5）：Docker鏡像基本操做（上）

一、獲取鏡像

可使用docker pull 命令從網絡上下載鏡像。該命令的格式爲docker pull NAME[:TAG]。對於Docker鏡像來講，若是不顯示地指定TAG，則默認會選擇latest標籤，即下載倉庫中最新版本的鏡像。

從Docker Hub的hello-world倉庫下載一個最新的鏡像：

1 [root@localhost ~]# docker pull hello-world 2 Using default tag: latest 3 latest: Pulling from library/hello-world 4 1b930d010525: Pull complete 5 Digest: sha256:92695bc579f31df7a63da6922075d0666e565ceccad16b59c3374d2cf4e8e50e 6 Status: Downloaded newer image for hello-world:latest

也能夠經過指定標籤來下載特定版本的某一個鏡像：

# docker pull ubuntu: 14.04

則會從倉庫下載14.04版本的鏡像。

也能夠選擇從其餘註冊服務器的倉庫下載。此時，須要在倉庫名稱前指定完整的倉庫註冊服務器的地址。例如從DockerPool社區的鏡像源dl.dockerpool.com下載最新的Ubuntu鏡像：

# docker pull dl.dockerpool.com:5000/ubuntu

下載鏡像到本地後，便可隨時使用該鏡像了。

二、 查看鏡像信息

使用docker images命令能夠列出本地主機已有的鏡像。

1 [root@localhost ~]# docker images 2 REPOSITORY TAG IMAGE ID CREATED SIZE 3 hello-world         latest              fce289e99eb9        4 months ago        1.84kB

該信息中列出了鏡像來自哪一個倉庫，鏡像的標籤信息，鏡像的ID號（惟一），建立時間，鏡像大小。

其中鏡像的ID信息很是重要，它惟一標識了鏡像

TAG信息用於標記來自同一個倉庫的不一樣鏡像。例如Ubuntu倉庫中有多個鏡像，經過TAG信息來區分發布版本，包括10.0四、12.0四、12.十、13.0四、14.04等標籤。

使用docker inspect命令能夠獲取該鏡像的詳細信息：

 1 [root@localhost ~]# docker inspect fce2  2 [  3  {  4         "Id": "sha256:fce289e99eb9bca977dae136fbe2a82b6b7d4c372474c9235adc1741675f587e",  5         "RepoTags": [  6             "hello-world:latest"
 7  ],  8         "RepoDigests": [  9             "hello-world@sha256:92695bc579f31df7a63da6922075d0666e565ceccad16b59c3374d2cf4e8e50e"
10  ], 11         "Parent": "", 12         "Comment": "", 13         "Created": "2019-01-01T01:29:27.650294696Z", 14         "Container": "8e2caa5a514bb6d8b4f2a2553e9067498d261a0fd83a96aeaaf303943dff6ff9", 15         "ContainerConfig": { 16             "Hostname": "8e2caa5a514b", 17             "Domainname": "", 18             "User": "", 19             "AttachStdin": false, 20             "AttachStdout": false, 21             "AttachStderr": false, 22             "Tty": false, 23             "OpenStdin": false, 24             "StdinOnce": false, 25             "Env": [ 26                 "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
27  ], 28             "Cmd": [ 29                 "/bin/sh", 30                 "-c", 31                 "#(nop) ", 32                 "CMD [\"/hello\"]"
33  ], 34             "ArgsEscaped": true, 35             "Image": "sha256:a6d1aaad8ca65655449a26146699fe9d61240071f6992975be7e720f1cd42440", 36             "Volumes": null, 37             "WorkingDir": "", 38             "Entrypoint": null, 39             "OnBuild": null, 40             "Labels": {} 41  }, 42         "DockerVersion": "18.06.1-ce", 43         "Author": "", 44         "Config": { 45             "Hostname": "", 46             "Domainname": "", 47             "User": "", 48             "AttachStdin": false, 49             "AttachStdout": false, 50             "AttachStderr": false, 51             "Tty": false, 52             "OpenStdin": false, 53             "StdinOnce": false, 54             "Env": [ 55                 "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
56  ], 57             "Cmd": [ 58                 "/hello"
59  ], 60             "ArgsEscaped": true, 61             "Image": "sha256:a6d1aaad8ca65655449a26146699fe9d61240071f6992975be7e720f1cd42440", 62             "Volumes": null, 63             "WorkingDir": "", 64             "Entrypoint": null, 65             "OnBuild": null, 66             "Labels": null
67  }, 68         "Architecture": "amd64", 69         "Os": "linux", 70         "Size": 1840, 71         "VirtualSize": 1840, 72         "GraphDriver": { 73             "Data": { 74                 "MergedDir": "/var/lib/docker/overlay2/c14d313df686c3b8675baca16d8e7c3a26fb5b5e7a29c9acb5c494e5bd7fd3a3/merged", 75                 "UpperDir": "/var/lib/docker/overlay2/c14d313df686c3b8675baca16d8e7c3a26fb5b5e7a29c9acb5c494e5bd7fd3a3/diff", 76                 "WorkDir": "/var/lib/docker/overlay2/c14d313df686c3b8675baca16d8e7c3a26fb5b5e7a29c9acb5c494e5bd7fd3a3/work"
77  }, 78             "Name": "overlay2"
79  }, 80         "RootFS": { 81             "Type": "layers", 82             "Layers": [ 83                 "sha256:af0b15c8625bb1938f1d7b17081031f649fd14e6b233688eea3c5483994a66a3"
84  ] 85  }, 86         "Metadata": { 87             "LastTagTime": "0001-01-01T00:00:00Z"
88  } 89  } 90 ]

docker inspect命令返回的是一個JSON格式的數據，若是咱們只要其中一項內容時，可使用-f參數來指定，例如，獲取鏡像的Architecture信息：

[root@localhost ~]# docker inspect -f {{".Architecture"}} fce2 amd64

注：在指定鏡像ID時，一般可使用該ID的前若干個字符組成的可區分字串來替代完整的ID。

3. 搜索鏡像

使用docker search 命令能夠搜索遠端倉庫中的共享的鏡像，默認搜索Docker Hub官方倉庫中的鏡像。用法爲docker search TERM，支持的參數包括：

• --automated=false 僅顯示自動建立的鏡像
• --no—trunc=false 輸出信息不截斷顯示
• -s，--stars=0 指定僅顯示評價爲指定星級以上的鏡像

例：搜索帶MySQL關鍵字的鏡像：

 1 [root@localhost ~]# docker search mysql  2 NAME DESCRIPTION STARS OFFICIAL AUTOMATED  3 mysql                                                  MySQL is a widely used, open-source relation…   8118 [OK]  4 mariadb                                                MariaDB is a community-developed fork of MyS…   2757 [OK]  5 mysql/mysql-server                                     Optimized MySQL Server Docker images. Create…   607                                     [OK]
 6 zabbix/zabbix-server-mysql                             Zabbix Server with MySQL database support       192                                     [OK]
 7 hypriot/rpi-mysql                                      RPi-compatible Docker Image with Mysql          113                                     
 8 zabbix/zabbix-web-nginx-mysql                          Zabbix frontend based on Nginx web-server wi…   101                                     [OK]
 9 centurylink/mysql                                      Image containing mysql. Optimized to be link…   60                                      [OK]
10 centos/mysql-57-centos7                                MySQL 5.7 SQL database server                   52                                      
11 1and1internet/ubuntu-16-nginx-php-phpmyadmin-mysql-5   ubuntu-16-nginx-php-phpmyadmin-mysql-5          50                                      [OK]
12 
13 ........

返回信息中包括鏡像名字、描述、星級、是否爲官方建立、是否自動建立。

默認的輸出結果將按照星級評價進行排序。

4. 刪除鏡像

使用docker rmi 命令能夠刪除鏡像，命令格式爲docker rmi IMAGE[IMAGE…]，其中IMAGE能夠爲標籤或ID。

 1 [root@localhost ~]# docker rmi 18d5  2 Untagged: sshd:dockerfile  3 Deleted: sha256:18d5664af46487403289dff918d23ce621486f2afd145c449d3c2c983a2709f7  4 Deleted: sha256:43deeebb36b02b8d7e4d6a218d1c850106ca9a26cb6f26e43a58d6e8aa136a48  5 Deleted: sha256:caea84a66e29e24b4ac4399cb1c901ecd2e09bf7ec347c7e5e2062300ce66cac  6 Deleted: sha256:f8635da9e84f2a903693565201db2aa75df4a21bc65dfcee59dfad62d2574ab3  7 Deleted: sha256:1f10d01a4c2d41bc6b9e18b4c920d6ceea49b4d497e4131e4044dbbd04be36cd  8 Deleted: sha256:ad6f5929dd219aa6b85c3f0f5e2675a89a84d081f8383c1af50f7e7e9668ce96  9 Deleted: sha256:9d02b0d7acac1e4d013c605607d8ef5f2bf98d65c8b10d7ab3401e86a34d8506 10 Deleted: sha256:130ac06b3615f905f707f4c1ce858862e3be060323df6f06ff8ad596e3b2dd8f 11 Deleted: sha256:b836e16004e45115e9935066527e52b8b71b1618a7dbc4264053ee5a184decc4 12 Deleted: sha256:f7d87c7c9299bcfa360d0cc4eaff3920cc31ced19e2a52d5e14bc8b833c79dc0 13 Deleted: sha256:33a3356b8103012f80d6d8fba36bf31668797d7763bb10141f7e269b84bffab6 14 Deleted: sha256:9e3603ab4baa1579c01a5ea46c6b4e5d4dabbdc5ece83037b19d811ec92f39e3 15 Deleted: sha256:426bf87611a37a08185f2027980ee84066767ddbc085c3cad75d1b6699a424ab 16 Deleted: sha256:1ae1c04577223796b7a9db73009c9cf01ea15df51054ed7309c69f41ca191c72 17 Deleted: sha256:24cb1ed621d355cfadfb01d42e43e6323c478f4ba93aa7f9d2ab12b2d1b738dd 18 Deleted: sha256:2cf94037953608bfc2a18074e90bb6512c05383c682174a9c39259bc1c9df235 19 Deleted: sha256:4d446b97ce30091bec25464ac5d29c1662337cfc272ea5086b5910a3a0325fdf 20 Deleted: sha256:6ebddd22646cf3782850ca860b8b41fba14875a78273c0ab698c39e893234b31 21 Deleted: sha256:1d91ab0bc845595e5011745832028de0de61789f6f682880119046593edbf450 22 Deleted: sha256:3abf6384ac0fc31f6d6f09a4dca83504e7dbf49221ad7a0a51447c8a3be13478 23 Deleted: sha256:6570fed3f8544fa734c8d7f8ab703a0bbddc982cefb25f7dfe7fcd17958725ec 24 Deleted: sha256:df54e206d037e2bb07a70930c9bc113425d0214dd7e909b1f7a436d637456477 25 Deleted: sha256:6848d5e515b16f81d3bd7beaef5ebf9ffbc5946cb12c226ae23b164d32d4a480 26 Deleted: sha256:515c5abd179590c453af0b01fd85f50576c5ac5ea50dcacbee97cd93cc9cc5ba 27 Deleted: sha256:07a0c2553354cc311bd72a0990b13a4b9e21ddb711aedc4d37d46156e18da597 28 Deleted: sha256:0548ebfd926851f287983a2e32d50a93e8b6cbc198c37acbeb5f94f577950566 29 Deleted: sha256:9fe44e8931880f539ea512d5924d4b949623de4525ceacaf81b3048adc0d2878 30 Deleted: sha256:9f54b94e27aec25cf06883cbb2c2aed7576ab58284bfab82df9c2bd3a5de7be5 31 Deleted: sha256:1c6ab3c810d38aa7511315f784947b94cb0f8a0e484bbaa73cf81fd6c65bf769

注：當有該鏡像建立的容器存在時，鏡像文件默認是沒法刪除的。若是要想強行刪除鏡像，可使用 –f 參數：

# docker rmi –f Ubuntu