Unable to modify files in container from docker - docker

Question

I am attempting to build an imaging by modifying some of the files in an existing image. However, the files are not changed by RUN commands. My dockerfile is
FROM vromero/activemq-artemis
ADD . .
RUN ls
RUN whoami
# Overwrite existing password file. The existing file is invulnerable, and
# cannot be modified by docker. I have no idea why.
RUN rm -f /var/lib/artemis/etc/artemis-users.properties
RUN ls -l /var/lib/artemis/etc
RUN mv passwords.txt /var/lib/artemis/etc/artemis-users.properties
RUN cat /var/lib/artemis/etc/artemis-users.properties
RUN touch /var/lib/artemis/etc/touch-test
# Add the predefined queues
RUN sed -i.bak '/<core/r queues.xml' /var/lib/artemis/etc/broker.xml
# EOF
The base image is from the public docker repository. When I run it, I get the following output
$ docker build .
Sending build context to Docker daemon 4.608 kB
Step 0 : FROM vromero/activemq-artemis
---> 4e0f54c798cc
Step 1 : ADD . .
---> 3efde5a1fdea
Removing intermediate container c8621adc900b
Step 2 : RUN ls
---> Running in 5c5dca9449da
Dockerfile
artemis
artemis-service
passwords.txt
queues.xml
---> 22c541f98339
Removing intermediate container 5c5dca9449da
Step 3 : RUN whoami
---> Running in f11fcd2e2c5b
root
---> 15ee9aeb4c15
Removing intermediate container f11fcd2e2c5b
Step 4 : RUN rm -f /var/lib/artemis/etc/artemis-users.properties
---> Running in ab4383f0bb91
---> 10877bdb08ee
Removing intermediate container ab4383f0bb91
Step 5 : RUN ls -l /var/lib/artemis/etc
---> Running in a5669c8808e8
total 24
-rw-r--r-- 1 artemis artemis 959 Oct 4 05:40 artemis-roles.properties
-rw-r--r-- 1 artemis artemis 968 Oct 4 05:40 artemis-users.properties
-rwxrwxr-x 1 artemis artemis 1342 Oct 4 05:40 artemis.profile
-rw-r--r-- 1 artemis artemis 1302 Oct 4 05:40 bootstrap.xml
-rw-r--r-- 1 artemis artemis 4000 Oct 4 05:40 broker.xml
-rw-r--r-- 1 artemis artemis 2203 Oct 4 05:40 logging.properties
---> 02e3acc58653
Removing intermediate container a5669c8808e8
Step 6 : RUN mv passwords.txt /var/lib/artemis/etc/artemis-users.properties
---> Running in 68000aa34f6b
---> ec057d5adc67
Removing intermediate container 68000aa34f6b
Step 7 : RUN cat /var/lib/artemis/etc/artemis-users.properties
---> Running in 934a36d8c4d1
## ---------------------------------------------------------------------------
## Licensed to the Apache Software Foundation (ASF) under one or more
## contributor license agreements. See the NOTICE file distributed with
## this work for additional information regarding copyright ownership.
## The ASF licenses this file to You under the Apache License, Version 2.0
## (the "License"); you may not use this file except in compliance with
## the License. You may obtain a copy of the License at
##
## http://www.apache.org/licenses/LICENSE-2.0
##
## Unless required by applicable law or agreed to in writing, software
## distributed under the License is distributed on an "AS IS" BASIS,
## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
## limitations under the License.
## ---------------------------------------------------------------------------
apollo=ollopaehcapa ---> ca1bad8a8903
Removing intermediate container 934a36d8c4d1
Step 8 : RUN touch /var/lib/artemis/etc/touch-test
---> Running in cb931c5cfcd1
---> 6961b4fcde75
Removing intermediate container cb931c5cfcd1
Step 9 : RUN sed -i.bak '/<core/r queues.xml' /var/lib/artemis/etc/broker.xml
---> Running in a829642b29ab
---> effd394fc02f
Removing intermediate container a829642b29ab
Successfully built effd394fc02f
The ADD . . has worked, as passwords.txt and queues.xml both show up in the ls. whoami shows that the current user is root, so there should be no permissions problems.
However, the existing files are not changed. If I run the image but use bash as the start command (see below), none of the files have a current date, although the file that was mv'ed to replace an existing file is gone. If I paste the sed command into the shell, it does update the file.
$ docker run -it effd394fc02f bash
root#51d1cc0a94cb:/var/lib/artemis/bin# ls -l
total 16
-rw-r--r-- 1 root root 543 Oct 21 22:12 Dockerfile
-rwxrwxr-x 1 artemis artemis 3416 Oct 4 05:40 artemis
-rwxrwxr-x 1 artemis artemis 3103 Oct 4 05:40 artemis-service
-rw-r--r-- 1 root root 329 Oct 21 22:18 queues.xml
root#51d1cc0a94cb:/var/lib/artemis/bin# cd ../etc
root#51d1cc0a94cb:/var/lib/artemis/etc# ls -l
total 24
-rw-r--r-- 1 artemis artemis 959 Oct 4 05:40 artemis-roles.properties
-rw-r--r-- 1 artemis artemis 968 Oct 4 05:40 artemis-users.properties
-rwxrwxr-x 1 artemis artemis 1342 Oct 4 05:40 artemis.profile
-rw-r--r-- 1 artemis artemis 1302 Oct 4 05:40 bootstrap.xml
-rw-r--r-- 1 artemis artemis 4000 Oct 4 05:40 broker.xml
-rw-r--r-- 1 artemis artemis 2203 Oct 4 05:40 logging.properties
Why are these files not being changed by the run commands?

Answer 1

The actual problem was related to how the base image was built. If you run docker history --no-trunc vromero/activemq-artemis, you see these commands (among others):
<id> 6 weeks ago /bin/sh -c #(nop) VOLUME [/var/lib/artemis/etc] 0 B
<id> 6 weeks ago /bin/sh -c #(nop) VOLUME [/var/lib/artemis/tmp] 0 B
<id> 6 weeks ago /bin/sh -c #(nop) VOLUME [/var/lib/artemis/data] 0 B
The Dockerfile volume documentation states
Note: If any build steps change the data within the volume after it
has been declared, those changes will be discarded.
This means that the configuration in the base image is locked.
I solved my problem by creating my own dockerfile based on the output of the history command, without the volume lines.

Answer 2

Not a complete answer, but at least a clue: you don't change the entrypoint of the built image.
That means your image will still execute the one from vromero/activemq-artemis, which, according to its Dockerfile is:
ENTRYPOINT ["/docker-entrypoint.sh"]
And docker-entrypoint.sh might reset some of your changes on docker run.

Answer 3

There are two RUN commands in Dockerfile.
You are running this: RUN <command> (the command is run in a shell - /bin/sh -c (shell form)
The other one is this: RUN ["executable", "param1", "param2"] (exec form)
Try this:
RUN ["rm", "-f", "/var/lib/artemis/etc/artemis-users.properties"]
RUN ["ls", "-l", "/var/lib/artemis/etc"]
RUN ["mv", "passwords.txt", "/var/lib/artemis/etc/artemis-users.properties"]
RUN ["cat", "/var/lib/artemis/etc/artemis-users.properties"]
RUN ["touch", "/var/lib/artemis/etc/touch-test"]
# Add the predefined queues
RUN ["sed", "-i.bak", "'/<core/r queues.xml'", "/var/lib/artemis/etc/broker.xml"]