【玩转Docker系列4】镜像和仓库
镜像和仓库
1.1 下载、查看镜像
1.1.1 通过命令直接下载镜像
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UbuntuTest:~ # docker pull ubuntu Using default tag: latest latest: Pulling from library/ubuntu 952132ac251a: Pull complete 82659f8f1b76: Pull complete c19118ca682d: Pull complete 8296858250fe: Pull complete 24e0251a0e2c: Pull complete Digest: sha256:f4691c96e6bbaa99d99ebafd9af1b68ace2aa2128ae95a60369c506dd6e6f6ab Status: Downloaded newer image for ubuntu:latest UbuntuTest:~ # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 12 days ago 126.6 MB python latest 0b5a17c108b6 7 weeks ago 694.2 MB golang latest c47d40563451 7 weeks ago 753.5 MB opensuse latest 76c8c565bc28 8 weeks ago 97.74 MB hello-world latest c54a2cc56cbb 9 weeks ago 1.848 kB testframe5.0 latest 1bd575496a8e 12 weeks ago 773.1 MB thezxm/redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB |
1.1.2 第一次创建容器时下载镜像（本地无此镜像）
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UbuntuTest:~ # docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world c04b14da8d14: Pull complete Digest: sha256:0256e8a36e2070f7bf2d0b0763dbabdd67798512411de4cdcf9431a1feb60fd9 Status: Downloaded newer image for hello-world:latest Hello from Docker! This message shows that your installation appears to be working correctly. To generate this message, Docker took the following steps: 1. The Docker client contacted the Docker daemon. 2. The Docker daemon pulled the "hello-world" image from the Docker Hub. 3. The Docker daemon created a new container from that image which runs the executable that produces the output you are currently reading. 4. The Docker daemon streamed that output to the Docker client, which sent it to your terminal. To try something more ambitious, you can run an Ubuntu container with: $ docker run -it ubuntu bash Share images, automate workflows, and more with a free Docker Hub account: https://hub.docker.com For more examples and ideas, visit: https://docs.docker.com/engine/userguide/ |
1.1.3 查看当前系统可用的镜像列表
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UbuntuTest:~ # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 12 days ago 126.6 MB python latest 0b5a17c108b6 7 weeks ago 694.2 MB golang latest c47d40563451 7 weeks ago 753.5 MB opensuse latest 76c8c565bc28 8 weeks ago 97.74 MB hello-world latest c54a2cc56cbb 9 weeks ago 1.848 kB testframe5.0 latest 1bd575496a8e 12 weeks ago 773.1 MB thezxm/redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB |
1.1.4 镜像文件后台存储位置
Docker相关文件存放在：/var/lib/docker目录下，镜像的存储结构主要分两部分，一是镜像ID之间的关联，一是镜像ID与镜像名称之间的关联，前者的结构体叫Graph，后者叫TagStore。
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UbuntuTest:/var/lib/docker # l total 60 drwx------ 5 root root 4096 Jul 22 04:35 aufs drwx------ 8 root root 4096 Sep 8 19:57 containers drwx------ 47 root root 4096 Jul 24 01:36 graph drwx------ 3 root root 4096 Jul 22 04:35 image drwx------ 2 root root 4096 Jul 23 19:26 init -rw-r--r-- 1 root root 11264 Sep 5 16:47 linkgraph.db drwxr-x--- 3 root root 4096 Jul 22 04:35 network -rw------- 1 root root 686 Jul 24 01:54 repositories-aufs drwx------ 2 root root 4096 Sep 5 16:47 swarm drwx------ 2 root root 4096 Sep 14 11:35 tmp drwx------ 2 root root 4096 Jul 22 04:35 trust drwx------ 3 root root 4096 Jul 24 01:28 vfs drwx------ 10 root root 4096 Sep 5 17:17 volumes |
1 Docker镜像后台存储文件列表：
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文件或目录名 |
说明 |
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/var/lib/docker/repositories-aufs |
TagStore的存储地方，里面有image id与reponame，tag之间的映射关系. aufs是driver名。 |
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/var/lib/docker/graph |
每个镜像的json描述文件和layersize大小。 |
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/var/lib/docker/aufs/diff |
每层layer与其父layer之间的文件差异，有的为空，有的有文件（镜像实际存储的地方）。 |
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/var/lib/docker/aufs/layers |
每层layer一个文件，记录其父layer一直到根layer之间的ID，每个ID一行。大部分文件的最后一行都一样，表示继承自同一个layer。 |
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/var/lib/docker/aufs/mnt |
有容器运行时里面有数据（容器数据实际存储的地方,包含整个文件系统数据），退出时里面为空。 |
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/var/lib/docker/volumes |
volumes卷的存储地。 |
1.2 删除、重命名镜像
1.2.1 删除镜像
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UbuntuTest:~ # docker rmi hello-world Untagged: hello-world:latest Untagged: hello-world@sha256:0256e8a36e2070f7bf2d0b0763dbabdd67798512411de4cdcf9431a1feb60fd9 Deleted: sha256:c54a2cc56cbb2f04003c1cd4507e118af7c0d340fe7e2720f70976c4b75237dc Deleted: sha256:a02596fdd012f22b03af6ad7d11fa590c57507558357b079c3e8cebceb4262d7 UbuntuTest:~ # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 12 days ago 126.6 MB python latest 0b5a17c108b6 7 weeks ago 694.2 MB golang latest c47d40563451 7 weeks ago 753.5 MB opensuse latest 76c8c565bc28 8 weeks ago 97.74 MB testframe5.0 latest 1bd575496a8e 12 weeks ago 773.1 MB redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB thezxm/redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB |
1.2.2 重命名镜像
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UbuntuTest:~ # docker tag thezxm/redhat7 redhat7 UbuntuTest:~ # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 12 days ago 126.6 MB python latest 0b5a17c108b6 7 weeks ago 694.2 MB golang latest c47d40563451 7 weeks ago 753.5 MB opensuse latest 76c8c565bc28 8 weeks ago 97.74 MB testframe5.0 latest 1bd575496a8e 12 weeks ago 773.1 MB thezxm/redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB |
1.3 查找镜像
如下图所示，其中OFFICIAL为OK表示该镜像是由上游开发者管理的镜像（如ubuntu镜像由Ubuntu团队管理和提供）。
搭建私有仓库
步骤1：获取registry镜像。
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UbuntuTest:~/dockerfile_test # docker pull registry:2.1.1 2.1.1: Pulling from library/registry Digest: sha256:4a9bc5424fa7cc4fafd88b5d8dfb102ceb339e8f418fdeca7f094c86db284f1c Status: Downloaded newer image for registry:2.1.1
UbuntuTest:~/dockerfile_test # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 3 weeks ago 126.6 MB registry 2.1.1 52bb991b482e 11 months ago 220.1 MB redhat7 latest 8feabc99ecd9 18 months ago 436.9 MB |
步骤2：运行已下载的registry镜像。
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UbuntuTest:~/dockerfile_test # docker run -d -v /opt/registry:/var/lib/registry -p 5000:5000 --restart=always --name registry registry:2.1.1 9d2df623dbce5468189ddea5945b133f90407ef49c15264308131dcb1f5b382a UbuntuTest:~/dockerfile_test # docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9d2df623dbce registry:2.1.1 "/bin/registry /etc/d" 9 seconds ago Up 8 seconds 0.0.0.0:5000->5000/tcp registry
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打开浏览器输入http://10.71.96.200:5000/v2，出现下面情况说明registry运行正常步骤3：从私有仓库下载镜像
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删除本地的127.0.0.1:5000/ubuntu_file_test和huguosheng888/ubuntu_file_test UbuntuTest:~/dockerfile_test # docker rmi huguosheng888/ubuntu_file_test UbuntuTest:~/dockerfile_test # docker rmi 127.0.0.1:5000/ubuntu_file_test -f UbuntuTest:~/dockerfile_test # docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu latest bd3d4369aebc 3 weeks ago 126.6 MB registry 2.1.1 52bb991b482e 11 months ago 220.1 MB
UbuntuTest:~/dockerfile_test # docker pull 127.0.0.1:5000/ubuntu_file_test Using default tag: latest latest: Pulling from ubuntu_file_test Digest: sha256:75ba99ae30de5fde5a8f0423f4251f904c8bf98fb4c556401613e57f9824d32f Status: Downloaded newer image for 127.0.0.1:5000/ubuntu_file_test:latest
UbuntuTest:~/dockerfile_test # docker images REPOSITORY TAG IMAGE ID CREATED SIZE 127.0.0.1:5000/ubuntu_file_test latest b80d42590d81 3 hours ago 126.8 MB ubuntu latest bd3d4369aebc 3 weeks ago 126.6 MB registry 2.1.1 52bb991b482e 11 months ago 220.1 MB |
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