Package: docker-squash
The problemDocker creates many layers while building the image. Sometimes it’s not necessary or desireable
to have them in the image. For example a DockerfileADDinstruction creates a single layer
with files you want to make available in the image. The problem arises when these files are
only temporary files (for example product distribution that you want to unpack). Docker will
carry this unnecessary layer always with the image, even if you delete these files in next
layer. This a waste of time (more data to push/load/save) and resources (bigger image).Squashing helps with organizing images in logical layers. Instead of
having an image with multiple (in almost all cases) unnecessary layers -
we can control the structure of the image.FeaturesCan squash last n layers from an imageCan squash from a selected layer to the end (not always possible, depends on the image)Support for Docker 1.9 or newer (older releases may run perfectly fine too, try it!)Squashed image can be loaded back to the Docker daemon or stored as tar archive somewhereInstallationFrom source code$ pip install --user https://github.com/goldmann/docker-squash/archive/master.zipFrom PyPi$ pip install docker-squashIt is supported on Python 3.6 and above.Usage$ docker-squash -h
usage: cli.py [-h] [-v] [--version] [-d] [-f FROM_LAYER] [-t TAG]
              [--tmp-dir TMP_DIR] [--output-path OUTPUT_PATH]
              image

Docker layer squashing tool

positional arguments:
  image                 Image to be squashed

optional arguments:
  -h, --help            show this help message and exit
  -v, --verbose         Verbose output
  --version             Show version and exit
  -f FROM_LAYER, --from-layer FROM_LAYER
                        Number of layers to squash or ID of the layer (or image ID or image name) to squash from.
                        In case the provided value is an integer, specified number of layers will be squashed.
                        Every layer in the image will be squashed if the parameter is not provided.
  -t TAG, --tag TAG     Specify the tag to be used for the new image. If not specified no tag will be applied
  -m MESSAGE, --message MESSAGE
                        Specify a commit message (comment) for the new image.
  -c, --cleanup         Remove source image from Docker after squashing
  --tmp-dir TMP_DIR     Temporary directory to be created and used. This will NOT be deleted afterwards for
                        easier debugging.
  --output-path OUTPUT_PATH
                        Path where the image may be stored after squashing.
  --load-image [LOAD_IMAGE]
                        Whether to load the image into Docker daemon after squashing
                        Default: trueNote that environment variables may be set as documented inhere.LicenseMITExamplesWe start with image like this:$ docker history jboss/wildfly:latest
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
25954e6d2300        3 weeks ago         /bin/sh -c #(nop) CMD ["/opt/jboss/wildfly/bi   0 B
5ae69cb454a5        3 weeks ago         /bin/sh -c #(nop) EXPOSE 8080/tcp               0 B
dc24712f35c4        3 weeks ago         /bin/sh -c #(nop) ENV LAUNCH_JBOSS_IN_BACKGRO   0 B
d929129d4c8e        3 weeks ago         /bin/sh -c cd $HOME     && curl -O https://do   160.8 MB
b8fa3caf7d6d        3 weeks ago         /bin/sh -c #(nop) ENV JBOSS_HOME=/opt/jboss/w   0 B
38b8f85e74bf        3 weeks ago         /bin/sh -c #(nop) ENV WILDFLY_SHA1=c0dd7552c5   0 B
ae79b646b9a9        3 weeks ago         /bin/sh -c #(nop) ENV WILDFLY_VERSION=10.0.0.   0 B
2b4606dc9dc7        3 weeks ago         /bin/sh -c #(nop) ENV JAVA_HOME=/usr/lib/jvm/   0 B
118fa9e33576        3 weeks ago         /bin/sh -c #(nop) USER [jboss]                  0 B
5f7e8f36c3bb        3 weeks ago         /bin/sh -c yum -y install java-1.8.0-openjdk-   197.4 MB
3d4d0228f161        3 weeks ago         /bin/sh -c #(nop) USER [root]                   0 B
f7ab4ea19708        3 weeks ago         /bin/sh -c #(nop) MAINTAINER Marek Goldmann <   0 B
4bb15f3b6977        3 weeks ago         /bin/sh -c #(nop) USER [jboss]                  0 B
5dc1e49f4361        3 weeks ago         /bin/sh -c #(nop) WORKDIR /opt/jboss            0 B
7f0f9eb31174        3 weeks ago         /bin/sh -c groupadd -r jboss -g 1000 && usera   4.349 kB
bd515f044af7        3 weeks ago         /bin/sh -c yum update -y && yum -y install xm   25.18 MB
b78336099045        3 weeks ago         /bin/sh -c #(nop) MAINTAINER Marek Goldmann <   0 B
4816a298548c        3 weeks ago         /bin/sh -c #(nop) CMD ["/bin/bash"]             0 B
6ee235cf4473        3 weeks ago         /bin/sh -c #(nop) LABEL name=CentOS Base Imag   0 B
474c2ee77fa3        3 weeks ago         /bin/sh -c #(nop) ADD file:72852fc7626d233343   196.6 MB
1544084fad81        6 months ago        /bin/sh -c #(nop) MAINTAINER The CentOS Proje   0 BAnd we want to squash all the layers down to layer4bb15f3b6977.$ docker-squash -f 4bb15f3b6977 -t jboss/wildfly:squashed jboss/wildfly:latest
2016-04-01 13:11:02,358 root         INFO     docker-scripts version 1.0.0dev, Docker 7206621, API 1.21...
2016-04-01 13:11:02,358 root         INFO     Using v1 image format
2016-04-01 13:11:02,374 root         INFO     Old image has 21 layers
2016-04-01 13:11:02,378 root         INFO     Checking if squashing is necessary...
2016-04-01 13:11:02,378 root         INFO     Attempting to squash last 12 layers...
2016-04-01 13:11:02,378 root         INFO     Saving image 25954e6d230006235eecb7f0cc560264d73146985c2d2e663bac953d660b8730 to /tmp/docker-squash-fbxZz4/old/image.tar file...
2016-04-01 13:11:08,003 root         INFO     Image saved!
2016-04-01 13:11:08,031 root         INFO     Unpacking /tmp/docker-squash-fbxZz4/old/image.tar tar file to /tmp/docker-squash-fbxZz4/old directory
2016-04-01 13:11:08,588 root         INFO     Archive unpacked!
2016-04-01 13:11:08,636 root         INFO     Squashing image 'jboss/wildfly:latest'...
2016-04-01 13:11:08,637 root         INFO     Starting squashing...
2016-04-01 13:11:08,637 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/25954e6d230006235eecb7f0cc560264d73146985c2d2e663bac953d660b8730/layer.tar'...
2016-04-01 13:11:08,637 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/5ae69cb454a5a542f63e148ce40fb9e01de5bb01805b4ded238841bc2ce8e895/layer.tar'...
2016-04-01 13:11:08,637 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/dc24712f35c40e958be8aca2731e7bf8353b9b18baa6a94ad84c6952cbc77004/layer.tar'...
2016-04-01 13:11:08,638 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/d929129d4c8e61ea3661eb42c30d01f4c152418689178afc7dc8185a37814528/layer.tar'...
2016-04-01 13:11:09,113 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/b8fa3caf7d6dc228bf2499a3af86e5073ad0c17304c3900fa341e9d2fe4e5655/layer.tar'...
2016-04-01 13:11:09,115 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/38b8f85e74bfa773a0ad69da2205dc0148945e6f5a7ceb04fa4e8619e1de425b/layer.tar'...
2016-04-01 13:11:09,115 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/ae79b646b9a9a287c5f6a01871cc9d9ee596dafee2db942714ca3dea0c06eef3/layer.tar'...
2016-04-01 13:11:09,115 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/2b4606dc9dc773aa220a65351fe8d54f03534c58fea230960e95915222366074/layer.tar'...
2016-04-01 13:11:09,115 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/118fa9e33576ecc625ebbbfdf2809c1527e716cb4fd5cb40548eb6d3503a75a9/layer.tar'...
2016-04-01 13:11:09,115 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/5f7e8f36c3bb20c9db7470a22f828710b4d28aede64966c425add48a1b14fe23/layer.tar'...
2016-04-01 13:11:10,127 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/3d4d0228f161b67eb46fdb425ad148c31d9944dcb822f67eac3e2ac2effefc73/layer.tar'...
2016-04-01 13:11:10,129 root         INFO     Squashing file '/tmp/docker-squash-fbxZz4/old/f7ab4ea197084ab7483a2ca5409bdcf5473141bfb61b8687b1329943359cc3fe/layer.tar'...
2016-04-01 13:11:10,732 root         INFO     Squashing finished!
2016-04-01 13:11:10,737 root         INFO     New squashed image ID is 52255e75d3eb83123e074f897e8c971dec9d1168a5c82d7c1496a190da2e40ef
2016-04-01 13:11:14,563 root         INFO     Image registered in Docker daemon as jboss/wildfly:squashed
2016-04-01 13:11:14,652 root         INFO     DoneWe can now confirm the layer structure:$ docker history jboss/wildfly:squashed
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
52255e75d3eb        40 seconds ago                                                      358.2 MB
4bb15f3b6977        3 weeks ago         /bin/sh -c #(nop) USER [jboss]                  0 B
5dc1e49f4361        3 weeks ago         /bin/sh -c #(nop) WORKDIR /opt/jboss            0 B
7f0f9eb31174        3 weeks ago         /bin/sh -c groupadd -r jboss -g 1000 && usera   4.349 kB
bd515f044af7        3 weeks ago         /bin/sh -c yum update -y && yum -y install xm   25.18 MB
b78336099045        3 weeks ago         /bin/sh -c #(nop) MAINTAINER Marek Goldmann <   0 B
4816a298548c        3 weeks ago         /bin/sh -c #(nop) CMD ["/bin/bash"]             0 B
6ee235cf4473        3 weeks ago         /bin/sh -c #(nop) LABEL name=CentOS Base Imag   0 B
474c2ee77fa3        3 weeks ago         /bin/sh -c #(nop) ADD file:72852fc7626d233343   196.6 MB
1544084fad81        6 months ago        /bin/sh -c #(nop) MAINTAINER The CentOS Proje   0 BOther option is to specify how many layers (counting from the newest layer) we want to squash.Let’s squash last 10 layers from thejboss/wildfly:latestimage:$ docker-squash -f 10 -t jboss/wildfly:squashed jboss/wildfly:latest
2016-04-01 13:15:06,488 root         INFO     docker-scripts version 1.0.0dev, Docker 7206621, API 1.21...
2016-04-01 13:15:06,488 root         INFO     Using v1 image format
2016-04-01 13:15:06,504 root         INFO     Old image has 21 layers
2016-04-01 13:15:06,504 root         INFO     Checking if squashing is necessary...
2016-04-01 13:15:06,504 root         INFO     Attempting to squash last 10 layers...
2016-04-01 13:15:06,505 root         INFO     Saving image 25954e6d230006235eecb7f0cc560264d73146985c2d2e663bac953d660b8730 to /tmp/docker-squash-fu80CX/old/image.tar file...
2016-04-01 13:15:12,136 root         INFO     Image saved!
2016-04-01 13:15:12,167 root         INFO     Unpacking /tmp/docker-squash-fu80CX/old/image.tar tar file to /tmp/docker-squash-fu80CX/old directory
2016-04-01 13:15:12,706 root         INFO     Archive unpacked!
2016-04-01 13:15:12,756 root         INFO     Squashing image 'jboss/wildfly:latest'...
2016-04-01 13:15:12,756 root         INFO     Starting squashing...
2016-04-01 13:15:12,756 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/25954e6d230006235eecb7f0cc560264d73146985c2d2e663bac953d660b8730/layer.tar'...
2016-04-01 13:15:12,757 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/5ae69cb454a5a542f63e148ce40fb9e01de5bb01805b4ded238841bc2ce8e895/layer.tar'...
2016-04-01 13:15:12,757 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/dc24712f35c40e958be8aca2731e7bf8353b9b18baa6a94ad84c6952cbc77004/layer.tar'...
2016-04-01 13:15:12,757 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/d929129d4c8e61ea3661eb42c30d01f4c152418689178afc7dc8185a37814528/layer.tar'...
2016-04-01 13:15:13,234 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/b8fa3caf7d6dc228bf2499a3af86e5073ad0c17304c3900fa341e9d2fe4e5655/layer.tar'...
2016-04-01 13:15:13,235 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/38b8f85e74bfa773a0ad69da2205dc0148945e6f5a7ceb04fa4e8619e1de425b/layer.tar'...
2016-04-01 13:15:13,235 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/ae79b646b9a9a287c5f6a01871cc9d9ee596dafee2db942714ca3dea0c06eef3/layer.tar'...
2016-04-01 13:15:13,235 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/2b4606dc9dc773aa220a65351fe8d54f03534c58fea230960e95915222366074/layer.tar'...
2016-04-01 13:15:13,236 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/118fa9e33576ecc625ebbbfdf2809c1527e716cb4fd5cb40548eb6d3503a75a9/layer.tar'...
2016-04-01 13:15:13,236 root         INFO     Squashing file '/tmp/docker-squash-fu80CX/old/5f7e8f36c3bb20c9db7470a22f828710b4d28aede64966c425add48a1b14fe23/layer.tar'...
2016-04-01 13:15:14,848 root         INFO     Squashing finished!
2016-04-01 13:15:14,853 root         INFO     New squashed image ID is fde7edd2e5683c97bedf9c0bf52ad5150db5650e421de3d9293ce5223b256455
2016-04-01 13:15:18,963 root         INFO     Image registered in Docker daemon as jboss/wildfly:squashed
2016-04-01 13:15:19,059 root         INFO     DoneLet’s confirm the image structure now:$ docker history jboss/wildfly:squashed
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
fde7edd2e568        32 seconds ago                                                      358.2 MB
3d4d0228f161        3 weeks ago         /bin/sh -c #(nop) USER [root]                   0 B
f7ab4ea19708        3 weeks ago         /bin/sh -c #(nop) MAINTAINER Marek Goldmann <   0 B
4bb15f3b6977        3 weeks ago         /bin/sh -c #(nop) USER [jboss]                  0 B
5dc1e49f4361        3 weeks ago         /bin/sh -c #(nop) WORKDIR /opt/jboss            0 B
7f0f9eb31174        3 weeks ago         /bin/sh -c groupadd -r jboss -g 1000 && usera   4.349 kB
bd515f044af7        3 weeks ago         /bin/sh -c yum update -y && yum -y install xm   25.18 MB
b78336099045        3 weeks ago         /bin/sh -c #(nop) MAINTAINER Marek Goldmann <   0 B
4816a298548c        3 weeks ago         /bin/sh -c #(nop) CMD ["/bin/bash"]             0 B
6ee235cf4473        3 weeks ago         /bin/sh -c #(nop) LABEL name=CentOS Base Imag   0 B
474c2ee77fa3        3 weeks ago         /bin/sh -c #(nop) ADD file:72852fc7626d233343   196.6 MB
1544084fad81        6 months ago        /bin/sh -c #(nop) MAINTAINER The CentOS Proje   0 B