Docker壁球行为
我有一个大的docker图像A，并创build一个新的Dockerfile
FROM A RUN rm /big-folder 我试图用以下方式构build图像：
docker build --squash -t B:latest .
图像大小不应该由/大文件夹目录的维度减less？
在我的实际testing中，图像A和B保持相同的大小为1,26 GB。
我做错了什么，或者我没有理解压扁选项的实际行为？
请注意，此function是实验性的，因此可能会在将来的版本中更改。 testing在17.03版完成。
从我的testing中，执行--squash将压缩仅在当前图像中添加的图层，而不更改或合并任何FROM图像图层。
$ # squash-a is a sample base image like your image A $ cat df.squash-a FROM busybox:latest ADD alpinetest.tgz /data $ # squash-b is built off of squash-a, and uses the squash flag when built $ cat df.squash-b FROM test-squash-a:latest RUN rm -rf /data $ # squash-c merges the dockerfiles for A and B $ cat df.squash-c FROM busybox:latest ADD alpinetest.tgz /data RUN rm -rf /data $ # standard build for A $ docker build -f df.squash-a -t test-squash-a:latest . Sending build context to Docker daemon 23.25 MB Step 1/2 : FROM busybox:latest ---> 7968321274dc Step 2/2 : ADD alpinetest.tgz /data ---> a417cffcd3d2 Removing intermediate container f15e9cd57375 Successfully built a417cffcd3d2 $ # build B with --squash $ docker build -f df.squash-b --squash -t test-squash-b:latest . Sending build context to Docker daemon 23.25 MB Step 1/2 : FROM test-squash-a:latest ---> a417cffcd3d2 Step 2/2 : RUN rm -rf /data ---> Running in 961044b8ee10 ---> f5939d65a51a Removing intermediate container 961044b8ee10 Successfully built f5939d65a51a $ # build C with --squash $ docker build -f df.squash-c --squash -t test-squash-c:latest . Sending build context to Docker daemon 23.25 MB Step 1/3 : FROM busybox:latest ---> 7968321274dc Step 2/3 : ADD alpinetest.tgz /data ---> Using cache ---> a417cffcd3d2 Step 3/3 : RUN rm -rf /data ---> Using cache ---> f5939d65a51a Successfully built f5939d65a51a $ # comparing images, A is large as expected, B didn't shrink, but C did $ docker images | grep squash | sort test-squash-a latest a417cffcd3d2 6 minutes ago 68 MB test-squash-b latest 74e05f2130be 2 minutes ago 68 MB test-squash-c latest 7562dac62351 2 minutes ago 1.11 MB $ # start inspecting the layers with the busybox base $ docker inspect -f '{{ .RootFS.Layers }}' busybox:latest [sha256:38ac8d0f5bb30c8b742ad97a328b77870afaec92b33faf7e121161bc78a3fec8] $ # layers in A adds one as expected $ docker inspect -f '{{ .RootFS.Layers }}' test-squash-a [sha256:38ac8d0f5bb30c8b742ad97a328b77870afaec92b33faf7e121161bc78a3fec8 sha256:3f4d2549e582599f3059fe3c869d4d353794b9064f8548c3a68629a4a93038d7] $ # layers in B includes both busybox and A despite being squashed $ docker inspect -f '{{ .RootFS.Layers }}' test-squash-b [sha256:38ac8d0f5bb30c8b742ad97a328b77870afaec92b33faf7e121161bc78a3fec8 sha256:3f4d2549e582599f3059fe3c869d4d353794b9064f8548c3a68629a4a93038d7 sha256:68e9b1791c54b45c785c04440ba9de6eefd566a09890821296d46aec9609d2de] $ # layers in C only adds a single layer on top of busybox despite 2 run commands $ docker inspect -f '{{ .RootFS.Layers }}' test-squash-c [sha256:38ac8d0f5bb30c8b742ad97a328b77870afaec92b33faf7e121161bc78a3fec8 sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef] $ # the history output shows that the squash is over a range of layers $ docker history test-squash-c IMAGE CREATED CREATED BY SIZE COMMENT 7562dac62351 10 minutes ago 0 B merge sha256:f5939d65a51a45b9c30f71a53a878e42be3135a1e0696615aa3b34ed39e5dd99 to sha256:7968321274dc6b6171697c33df7815310468e694ac5be0ec03ff053bb135e768 <missing> 10 minutes ago /bin/sh -c rm -rf /data 0 B <missing> 13 minutes ago /bin/sh -c #(nop) ADD file:8993cc512c40cc0... 0 B <missing> 2 months ago /bin/sh -c #(nop) CMD ["sh"] 0 B <missing> 2 months ago /bin/sh -c #(nop) ADD file:707e63805c0be1a... 1.11 MB