docker rollback image changes

readme.txt

That’s one of the real strengths of Docker: the ability to go back to a previous commit. The secret is simply to docker tag the image you want.

Here’s an example. In this example, I first installed ping, then committed, then installed curl, and committed that. Then I rolled back the image to contain only ping:

$ docker history imagename
IMAGE               CREATED             CREATED BY                SIZE
f770fc671f11        12 seconds ago      apt-get install -y curl   21.3 MB
28445c70c2b3        39 seconds ago      apt-get install ping      11.57 MB
8dbd9e392a96        7 months ago                                  131.5 MB

$ docker tag 2844 imagename   # <-- that's the secret right there

$ docker history imagename
IMAGE               CREATED             CREATED BY             SIZE
28445c70c2b3        56 seconds ago      apt-get install ping   11.57 MB
8dbd9e392a96        7 months ago                               131.5 MB
==========================

  But maybe the best things are rollbacks: since every image contains all of its building steps, we can easily go back to a previous step if we want so. This can be done tagging a certain layer. Let’s take a look at image b again:
 
$ docker history test/b
IMAGE               CREATED             CREATED BY                                      SIZE
c0daf4be2ed4        3 hours ago         /bin/sh -c touch /opt/b.txt                     8 B
9977b78fbad7        3 hours ago         /bin/sh -c apt-get install -y apache2           54.17 MB
e83b3bf07b42        3 hours ago         /bin/sh -c apt-get update                       20.67 MB
9cd978db300e        3 months ago        /bin/sh -c #(nop) ADD precise.tar.xz in /       204.4 MB
6170bb7b0ad1        3 months ago        /bin/sh -c #(nop) MAINTAINER Tianon Gravi <ad   0 B
511136ea3c5a        10 months ago                                                       0 B
If we want to make a rollback and remove the last layer (maybe the file should be called c.txt instead of b.txt) we can do so by tagging the layer 9977b78fbad7:


1
$ docker tag 9977b test/b
Let’s take a look at the new history:

 
$ docker history test/b
IMAGE               CREATED             CREATED BY                                      SIZE
9977b78fbad7        3 hours ago         /bin/sh -c apt-get install -y apache2           54.17 MB
e83b3bf07b42        3 hours ago         /bin/sh -c apt-get update                       20.67 MB
9cd978db300e        3 months ago        /bin/sh -c #(nop) ADD precise.tar.xz in /       204.4 MB
6170bb7b0ad1        3 months ago        /bin/sh -c #(nop) MAINTAINER Tianon Gravi <ad   0 B
511136ea3c5a        10 months ago                                                       0 B
Our last layer is gone and with the layer the text file b.txt!