Dockerfile volume 测试

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Dockerfile volume 测试

最近在使用开源Image 作为基础进行新image创建的时候，遇到Volume问题，特进行测试并进行记录。

使用busybox 作为最基础的image，创建以下dockerfile

• volume 基础镜像Dockerfile base-Dockerfile

    FROM busybox 
    RUN   mkdir /volume /commdir
    RUN  adduser --uid 111 test -D
    RUN touch /volume/filebefore
    VOLUME /volume
    RUN touch /volume/fileafter
    ADD ./basetest /volume
  

• 子image ,Dockerfile

    FROM volume-test-base
    COPY ./test /volume/test
    COPY ./test /commdir/test
    RUN chown -hR test /volume
    RUN chown -hR test /commdir
  

• 一个测试脚本

    echo "test" >./test
    echo "base" >./basetest
    docker build -t volume-test-base . -f base-Dockerfile  --no-cache 
    docker build -t volume-test  .  --no-cache 
    docker run --rm -it volume-test  ls  -ltr /commdir 
    docker run --rm -it volume-test  ls  -ltr /volume 
  
    docker run --rm -it volume-test-base   ls  -ltr /volume 
  

运行结果如下：

 [email protected]:/media/psf/57root/dockerfile-volume-test# ./test.sh
Sending build context to Docker daemon  6.144kB
Step 1/7 : FROM busybox
 ---> 7968321274dc
Step 2/7 : RUN mkdir /volume /commdir
 ---> Running in a2488b3340a7
 ---> 6110c6a34c7b
Removing intermediate container a2488b3340a7
Step 3/7 : RUN adduser --uid 111 test -D
 ---> Running in 72eaa1f07426
 ---> f1f4995f8751
Removing intermediate container 72eaa1f07426
Step 4/7 : RUN touch /volume/filebefore
 ---> Running in b11a1bacb99f
 ---> 2c16779576d9
Removing intermediate container b11a1bacb99f
Step 5/7 : VOLUME /volume
 ---> Running in ae30df4e3bd3
 ---> fa81508eca60
Removing intermediate container ae30df4e3bd3
Step 6/7 : RUN touch /volume/fileafter
 ---> Running in a873cc8a0038
 ---> 9119dfff6d69
Removing intermediate container a873cc8a0038
Step 7/7 : ADD ./basetest /volume
 ---> 25b66efc3f7e
Removing intermediate container 10df898a8bbb
Successfully built 25b66efc3f7e
Successfully tagged volume-test-base:latest
Sending build context to Docker daemon  6.144kB
Step 1/5 : FROM volume-test-base
 ---> 25b66efc3f7e
Step 2/5 : COPY ./test /volume/test
 ---> ee3f4f23b10c
Removing intermediate container 8dcc417ab135
Step 3/5 : COPY ./test /commdir/test
 ---> 37b823ebb23a
Removing intermediate container e85340587c47
Step 4/5 : RUN chown -hR test /volume
 ---> Running in 137e7d72d4b7
 ---> a2b155e02fad
Removing intermediate container 137e7d72d4b7
Step 5/5 : RUN chown -hR test /commdir
 ---> Running in acc3ffc39114
 ---> 02454129541c
Removing intermediate container acc3ffc39114
Successfully built 02454129541c
Successfully tagged volume-test:latest
total 4
-rw-r--r--    1 test     root             5 Aug 18 15:51 test
total 8
-rw-r--r--    1 root     root             5 Aug 18 15:51 test
-rw-r--r--    1 root     root             5 Aug 18 15:51 basetest
-rw-r--r--    1 root     root             0 Aug 18 15:51 filebefore
total 4
-rw-r--r--    1 root     root             5 Aug 18 15:51 basetest
-rw-r--r--    1 root     root             0 Aug 18 15:51 filebefore

可以看到：

• 所有文件被保存在volume中
• 所有在VOLUMNE 的操作都没有被保存，无论是touch 还是chown

查看volume 也可以看到文件owner还都是root

    [email protected]:/media/psf/57root/robert-gz.github.io/_posts# docker run -d -it volume-test sh -c cat
    73526055f3b4896f63e74ed8b2d801610e7cadea05dcce583b0450c019da9564
    [email protected]:/media/psf/57root/robert-gz.github.io/_posts# docker ps
    CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
    73526055f3b4        volume-test         "sh -c cat"         2 seconds ago       Up 2 seconds                            elated_darwin
    [email protected]:/media/psf/57root/robert-gz.github.io/_posts# docker volume ls
    DRIVER              VOLUME NAME
    local               e5b8d7b756457713846bff2234016b0dd05a59a1303ac416197b8e9ece664d25
    [email protected]:/media/psf/57root/robert-gz.github.io/_posts# ls -ltr /var/lib/docker/volumes/e5b8d7b756457713846bff2234016b0dd05a59a1303ac416197b8e9ece664d25/_data
    total 8
    -rw-r--r-- 1 root root 5 Aug 18 23:51 test
    -rw-r--r-- 1 root root 5 Aug 18 23:51 basetest
    -rw-r--r-- 1 root root 0 Aug 18 23:51 filebefore

总之，dockerfile 里面volume 存放文件没有问题，但如果要修改用户及其它操作，必须在容器启动后自行处理，dockerfile里面设置是无效的