docker的存儲目錄遷移

（轉載的文章，親測有效）

docker的默認存儲目錄是/var/lib/docker,目錄結構如下：

    [root@ztscshop docker]# cd /var/lib/docker
    [root@ztscshop docker]# ll
    total 64
    drwx------  2 root root  4096 Jan 24  2019 builder
    drwx------  4 root root  4096 Jan 24  2019 buildkit
    drwx--x--x  3 root root  4096 Jan 24  2019 containerd
    drwx------  4 root root  4096 Oct 24 15:05 containers
    drwx------  3 root root  4096 Jan 24  2019 image
    drwxr-x---  3 root root  4096 Jan 24  2019 network
    drwx------ 80 root root 16384 Oct 24 15:25 overlay2
    drwx------  4 root root  4096 Jan 24  2019 plugins
    drwx------  2 root root  4096 Oct 22 11:57 runtimes
    drwx------  2 root root  4096 Jan 24  2019 swarm
    drwx------  2 root root  4096 Oct 24 15:13 tmp
    drwx------  2 root root  4096 Jan 24  2019 trust
    drwx------ 15 root root  4096 Feb  7  2019 volumes
    [root@ztscshop docker]# 

docker所有自身的東西都會存在這些文件夾下面包括鏡像文件和容器，所以會占用越來越多的磁盤空間。

如果docker所在的磁盤空間比較小，磁盤空間被占滿沒有空間的時候，顯然會導致docker容器運行失敗，此時必然要遷移docker的存儲目錄到一個更大的磁盤下面。

1.查看磁盤占用情況：df -h

    [root@ecs-8f49 ~]# df -h
    Filesystem      Size  Used Avail Use% Mounted on
    devtmpfs        7.8G     0  7.8G   0% /dev
    tmpfs           7.8G     0  7.8G   0% /dev/shm
    tmpfs           7.8G   73M  7.7G   1% /run
    tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup
    /dev/vda1        40G   13G   25G  33% /
    tmpfs           1.6G     0  1.6G   0% /run/user/0
    overlay          40G   13G   25G  33% /var/lib/docker/overlay2/53eb033fae8fadc98df74b118e743092fcd0ee68b579c2b771288c3c023b0b8b/merged
    shm              64M     0   64M   0% /var/lib/docker/containers/8ecb90f024c08468c5f32e7c8b8b0d1ff87616536e6c2155cfb58447bded3071/shm

2.查看docker自身的內存占用：docker system df

    [root@ecs-8f49 ~]# docker system df
    TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
    Images              16                  12                  2.893 GB            1.535 GB (53%)
    Containers          12                  1                   155.6 MB            155.6 MB (100%)
    Local Volumes       1                   1                   4.212 GB            0 B (0%)

3.docker system prune命令可以用於清理磁盤，刪除關閉的容器、無用的數據卷和網絡，以及dangling鏡像(即無tag的鏡像)。

    [root@ecs-8f49 ~]# docker system prune
    WARNING! This will remove:
        - all stopped containers
        - all volumes not used by at least one container
        - all networks not used by at least one container
        - all dangling images
    Are you sure you want to continue? [y/N] y
    Deleted Containers:
    9bd48276fcd28b3882605fd67a156a7ea848f8fbfe16c3588b630955dfda253d
    74af4504bdefbc58b83a476c12d6ce10260f91349eed0e5bfca5e51b86fb8474
    d405d43eeb7908472b4b8712f668ca3b97f3796f6afc1c1d19a15879140ddf64
    9f645670de22840d04249351d07b2f68f77754e4dfebdb4b39c56d827d6b6805
    79d32c6b3c34bb359cbbf8309d7be34074da391d3b48083f456a5911259a5213
    ad7137d7e018144e17790a3c86a8217a95faecd07a39003bc4df275c8c8d351d
    b02eb42677a52663e50fc4a2b1344d37a8d2a2cca445fe5eae49648a0ca54b13
    0813454a5421cf380b72265c2e6832411a590479424dbc3470e47e1cc9cdd740
    a58b5f545ce1cd03a2899ba277641b5f52203802d9672c72f281f2d5a31fc219
    936e65f72c60d754cb2a1441d0cdeb18f9a7ebde353f091fc44a034733fed52c
    ad86565bd85af04f5847703ba213d226c7d7b69e5210211e4170671d3ea4051c

    Deleted Volumes:
    37620879ca58c052c47e7677a1851f45c25cbc0437c8883cc2fe8e70e1cb921a

    Total reclaimed space: 4.368 GB

4.docker system prune -a命令清理得更加徹底，可以將沒有容器使用Docker鏡像都刪掉。注意，這兩個命令會把你暫時關閉的容器，以及暫時沒有用到的Docker鏡像都刪掉了…所以使用之前一定要想清楚.。我沒用過，因為會清理 沒有開啟的 Docker 鏡像。

5.遷移/var/lib/docker目錄。

5.1 停止docker服務

    systemctl stop docker

5.2 創建新的docker目錄，執行命令df -h,找一個大的磁盤。 我在 /home目錄下面建了 /home/docker/lib目錄，執行的命令是：

    mkdir -p /home/docker/lib

5.3 遷移/var/lib/docker目錄下面的文件到 /home/docker/lib：

(rsync是linux文件夾同步的命令，參數要加一個-r,因為文件夾要遞歸copy，如果在同一台服務器上面，直接cp也是可以的)

 

    rsync -r -avz /var/lib/docker /home/docker/lib/

5.4 配置 /etc/systemd/system/docker.service.d/devicemapper.conf。查看 devicemapper.conf 是否存在。如果不存在，就新建。

    mkdir -p /etc/systemd/system/docker.service.d/
    vi /etc/systemd/system/docker.service.d/devicemapper.conf

5.5 然后在 devicemapper.conf 寫入：（同步的時候把父文件夾一並同步過來，實際上的目錄應在 /home/docker/lib/docker ）

    [Service]
    ExecStart=
    ExecStart=/usr/bin/dockerd --graph=/home/docker/lib/docker

5.6 重新加載 docker

    systemctl daemon-reload

    systemctl restart docker

    systemctl enable docker

5.7 為了確認一切順利，運行

    docker info

命令檢查Docker 的根目錄.它將被更改為 /home/docker/lib/docker

    ...
    Docker Root Dir: /home/docker/lib/docker
    Debug Mode (client): false
    Debug Mode (server): false
    Registry: https://index.docker.io/v1/
    ...

5.8 啟動成功后，再確認之前的鏡像還在：

    root@nn0:~$ docker images
    REPOSITORY TAG IMAGE ID CREATED SIZE
    AAA/AAA v2 7331b8651bcc 27 hours ago 3.85GB
    BBB/BBB v1 da4a80dd8424 28 hours ago 3.47GB

5.9 確定容器沒問題后刪除/var/lib/docker/目錄中的文件。

6.遷移/var/lib/docker目錄后，Docker無法啟動 (error initializing graphdriver: driver not supported)

啟動信息

    [root@nn0 ~]# systemctl start docker
    Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.

啟動詳情

    8月 31 01:47:25 localhost.localdomain systemd[1]: Starting Docker Application Container Engine...
    -- Subject: Unit docker.service has begun start-up
    -- Defined-By: systemd
    -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
    -- 
    -- Unit docker.service has begun starting up.
    8月 31 01:47:25 localhost.localdomain dockerd[2390]: time="2018-08-31T01:47:25.197015872+08:00" level=info msg="libcontainerd: new containerd process, pid: 2393"
    8月 31 01:47:26 localhost.localdomain dockerd[2390]: time="2018-08-31T01:47:26.204103195+08:00" level=error msg="[graphdriver] prior storage driver overlay2 failed: driver not supported"
    8月 31 01:47:26 localhost.localdomain dockerd[2390]: Error starting daemon: error initializing graphdriver: driver not supported
    8月 31 01:47:26 localhost.localdomain systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
    8月 31 01:47:26 localhost.localdomain systemd[1]: Failed to start Docker Application Container Engine.

錯誤原因：error initializing graphdriver: driver not supported

解決辦法：在 /etc/docker 目錄下創建daemon.json文件，並且加入以下配置

    touch daemon.json
    vi daemon.json
    {
      "storage-driver": "overlay2",
      "storage-opts": [
        "overlay2.override_kernel_check=true"
      ]
    }

再次啟動：systemctl start docker

7. docker-runc not installed on system 問題

問題描述

docker運行鏡像的時候，報錯如下：
(如果報錯端口映射的錯誤，那就先不映射端口直接啟動鏡像，試一下是不是這個錯誤，因為如果直接映射端口啟動鏡像的話，這個錯誤導致容器啟動失敗，但是報錯是端口映射失敗)

    [root@nn0 k8s]# docker run -it registry.helloworld.com/test/atsd:latest bash
    WARNING: IPv4 forwarding is disabled. Networking will not work.
    /usr/bin/docker-current: Error response from daemon: shim error: docker-runc not installed on system.

問題解決：

    [root@nn0 k8s]# cd /usr/libexec/docker/
    [root@nn0 docker]# ln -s docker-runc-current docker-runc