This is a MWE of my Dockerfile: (I'm hand-composing, not using docker-compose)
# escape=`
FROM mcr.microsoft.com/windows/servercore:ltsc2019-amd64
SHELL ["cmd", "/S", "/C"]
RUN set zz=foo && echo %zz%
When I build the container, I expect this to print foo, but instead I get %zz% which seems to indicate that echo doesn't see the variable zz set.
Step 20/24 : RUN set zz=foo && echo %zz%
---> Running in b1f462e81c5c
%zz%
Removing intermediate container b1f462e81c5c
---> 9c0abf6eb928
If I run this on the command line, it works as expected:
C:\> cmd /S /C set zz=foo && echo %zz%
foo
How can I make the RUN instruction work like the command prompt?
My actual use case, in case this is an XY problem: I'm reading the contents of a user-provided file into a variable and then using that in a command which sets some global config file.
RUN `
set /p pat=<your_pat.txt && `
git config --global url."https://%pat%#github.com/".insteadOf "https://github.com/"
Related
How to run sed command and save the result to one new Variable in docker.
The sed will replace the last occurrence of '.' and replace with '_'
Example :
JOB_NAME_WITH_VERSION = test_git_0.1 and wanted result is ZIP_FILE_NAME = test_git_0_1
--Dockerfile
RUN ZIP_FILE_NAME=$(echo ${JOB_NAME_WITH_VERSION} | sed 's/\(.*\)\./\1_/') && export ZIP_FILE_NAME
RUN echo "Zip file Name found : $ZIP_FILE_NAME"
I tried this in my docker file but the result is empty
Zip file Name found :
The issue here is that every RUN command results in a new layer, so whatever shell variable was declared in previous layers is subsequently lost.
Compare this:
FROM ubuntu
RUN JOB="FOOBAR"
RUN echo "${JOB}"
$ docker build .
...
Step 3/3 : RUN echo "${JOB}"
---> Running in c4b7d1632c7e
...
to this:
FROM ubuntu
RUN JOB="FOOBAR" && echo "${JOB}"
$ docker build .
...
Step 2/2 : RUN JOB="FOOBAR" && echo "${JOB}"
---> Running in c11049d1687f
FOOBAR
...
so as a workaround, if using a single RUN command is not an option for whatever reason, write the variable to disk and read it when needed, e.g.:
FROM ubuntu
RUN JOB="FOOBAR" && echo "${JOB}" > /tmp/job_var
RUN cat /tmp/job_var
$ docker build .
...
Step 3/3 : RUN cat /tmp/job_var
---> Running in a346c30c2cd5
FOOBAR
...
Each RUN statement in a Dockerfile is run in a separate shell. So once a statement is done, all environment variables are lost. Even if they are exported.
To do what you want to do, you can combine your RUN statements like this
RUN ZIP_FILE_NAME=$(echo ${JOB_NAME_WITH_VERSION} | sed 's/\(.*\)\./\1_/') && \
export ZIP_FILE_NAME && \
echo "Zip file Name found : $ZIP_FILE_NAME"
As your variable is lost once the RUN statement is finished, your environment variable won't be available in your container when it runs. To have an environment variable available there, you need to use the ENV statement.
Inside my Dockerfile:
ENV PROJECTNAME mytestwebsite
CMD ["django-admin", "startproject", "$PROJECTNAME"]
Error:
CommandError: '$PROJECTNAME' is not a valid project name
What is the quickest workaround here? Does Docker have any plan to "fix" or introduce this functionality in later versions of Docker?
NOTE: If I remove the CMD line from the Docker file and then run the Docker container, I am able to manually run Django-admin startproject $PROJECTNAME from inside the container and it will create the project...
When you use an execution list, as in...
CMD ["django-admin", "startproject", "$PROJECTNAME"]
...then Docker will execute the given command directly, without involving a shell. Since there is no shell involved, that means:
No variable expansion
No wildcard expansion
No i/o redirection with >, <, |, etc
No multiple commands via command1; command2
And so forth.
If you want your CMD to expand variables, you need to arrange for a shell. You can do that like this:
CMD ["sh", "-c", "django-admin startproject $PROJECTNAME"]
Or you can use a simple string instead of an execution list, which gets you a result largely identical to the previous example:
CMD django-admin startproject $PROJECTNAME
If you want to use the value at runtime, set the ENV value in the Dockerfile. If you want to use it at build-time, then you should use ARG.
Example :
ARG value
ENV envValue=$value
CMD ["sh", "-c", "java -jar ${envValue}.jar"]
Pass the value in the build command:
docker build -t tagName --build-arg value="jarName"
You also can use exec
This is the only known way to handle signals and use env vars simultaneously.
It can be helpful while trying to implement something like graceful shutdown according to Docker github
Example:
ENV PROJECTNAME mytestwebsite
CMD exec django-admin startproject $PROJECTNAME
Lets say you want to start a java process inside a container:
Example Dockerfile excerpt:
ENV JAVA_OPTS -XX +UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=1 -XshowSettings:vm
...
ENTRYPOINT ["/sbin/tini", "--", "entrypoint.sh"]
CMD ["java", "${JAVA_OPTS}", "-myargument=true"]
Example entrypoint.sh excerpt:
#!/bin/sh
...
echo "*** Startup $0 suceeded now starting service using eval to expand CMD variables ***"
exec su-exec mytechuser $(eval echo "$#")
For the Java developers, following my solution below gonna work:
if you tried to run your container with a Dockerfile like below
ENTRYPOINT ["/docker-entrypoint.sh"]
# does not matter your parameter $JAVA_OPTS wrapped as ${JAVA_OPTS}
CMD ["java", "$JAVA_OPTS", "-javaagent:/opt/newrelic/newrelic.jar", "-server", "-jar", "app.jar"]
with an ENTRYPOINT shell script below:
#!/bin/bash
set -e
source /work-dir/env.sh
exec "$#"
it will build the image correctly but print the error below during the run of container:
Error: Could not find or load main class $JAVA_OPTS
Caused by: java.lang.ClassNotFoundException: $JAVA_OPTS
instead, Java can read the command line parameters either through the command line or by _JAVA_OPTIONS environment variable. so, it means we can pass the desired command line parameters through _JAVA_OPTIONS without changing anything on Dockerfile as well as to allow it to be able to start as parent process of container for the valid docker signalization via exec "$#".
The below one is my final version of the Dockerfile and docker-entrypoint.sh files:
...
ENTRYPOINT ["/docker-entrypoint.sh"]
CMD ["java", "-server", "-jar", "app.jar"]
#!/bin/bash
set -e
source /work-dir/env.sh
export _JAVA_OPTIONS="-XX:+PrintFlagsFinal"
exec "$#"
and after you build your docker image and tried to run it, you will see the logs below that means it worked well:
Picked up _JAVA_OPTIONS: -XX:+PrintFlagsFinal
[Global flags]
int ActiveProcessorCount = -1 {product} {default}
Inspired on above, I did this:
#snapshot by default. 1 is release.
ENV isTagAndRelease=0
CMD echo is_tag: ${isTagAndRelease} && \
if [ ${isTagAndRelease} -eq 1 ]; then echo "release build"; mvn -B release:clean release:prepare release:perform; fi && \
if [ ${isTagAndRelease} -ne 1 ]; then echo "snapshot build"; mvn clean install; fi && \
.....
I need to set some environment variable for all users and processes inside docker container. It should be set at container start, not in Dockerfile, because it depends on running environment.
So the simple Dockerfile
FROM ubuntu
RUN echo 'export TEST=test' >> '/root/.bashrc'
works well for interactive sessions
docker run -ti test bash
then
env
and there is TEST=test
but when docker run -ti test env there is no TEST
I was trying
RUN echo 'export TEST=test' >> '/etc/environment'
RUN echo 'TEST="test"' >> '/etc/environment'
RUN echo 'export TEST=test' >> /etc/profile.d/1.sh
ENTRYPOINT export TEST=test
Nothing helps.
Why I need this. I have http_proxy variable inside container automatically set by docker, I need to set another variables, based on it, i.e. JAVA_OPT, do it system wide, for all users and processes, and in running environment, not at build time.
I would create a script which would be an entrypoint:
#!/bin/bash
# if env variable is not set, set it
if [ -z $VAR ];
then
# env variable is not set
export VAR=$(a command that gives the var value);
fi
# pass the arguments received by the entrypoint.sh
# to /bin/bash with command (-c) option
/bin/bash -c $#
And in Dockerfile I would set the entrypoint:
ENTRYPOINT entrypoint.sh
Now every time I run docker run -it <image> <any command> it uses my script as entrypoint so will always run it before the command then pass the arguments to the right place which is /bin/bash.
Improvements
The above script is enough to work if you are always using the entrypoint with arguments, otherwise your $# variable will be empty and will give you an error /bin/bash: -c: option requires an argument. A easy fix is an if statement:
if [ ! -z $# ];
then
/bin/bash -c $#;
fi
Setting the parameter in ENTRYPOINT would solve this issue.
In docker file pass parameter in ENTRYPOINT
Inside my Dockerfile:
ENV PROJECTNAME mytestwebsite
CMD ["django-admin", "startproject", "$PROJECTNAME"]
Error:
CommandError: '$PROJECTNAME' is not a valid project name
What is the quickest workaround here? Does Docker have any plan to "fix" or introduce this functionality in later versions of Docker?
NOTE: If I remove the CMD line from the Docker file and then run the Docker container, I am able to manually run Django-admin startproject $PROJECTNAME from inside the container and it will create the project...
When you use an execution list, as in...
CMD ["django-admin", "startproject", "$PROJECTNAME"]
...then Docker will execute the given command directly, without involving a shell. Since there is no shell involved, that means:
No variable expansion
No wildcard expansion
No i/o redirection with >, <, |, etc
No multiple commands via command1; command2
And so forth.
If you want your CMD to expand variables, you need to arrange for a shell. You can do that like this:
CMD ["sh", "-c", "django-admin startproject $PROJECTNAME"]
Or you can use a simple string instead of an execution list, which gets you a result largely identical to the previous example:
CMD django-admin startproject $PROJECTNAME
If you want to use the value at runtime, set the ENV value in the Dockerfile. If you want to use it at build-time, then you should use ARG.
Example :
ARG value
ENV envValue=$value
CMD ["sh", "-c", "java -jar ${envValue}.jar"]
Pass the value in the build command:
docker build -t tagName --build-arg value="jarName"
You also can use exec
This is the only known way to handle signals and use env vars simultaneously.
It can be helpful while trying to implement something like graceful shutdown according to Docker github
Example:
ENV PROJECTNAME mytestwebsite
CMD exec django-admin startproject $PROJECTNAME
Lets say you want to start a java process inside a container:
Example Dockerfile excerpt:
ENV JAVA_OPTS -XX +UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=1 -XshowSettings:vm
...
ENTRYPOINT ["/sbin/tini", "--", "entrypoint.sh"]
CMD ["java", "${JAVA_OPTS}", "-myargument=true"]
Example entrypoint.sh excerpt:
#!/bin/sh
...
echo "*** Startup $0 suceeded now starting service using eval to expand CMD variables ***"
exec su-exec mytechuser $(eval echo "$#")
For the Java developers, following my solution below gonna work:
if you tried to run your container with a Dockerfile like below
ENTRYPOINT ["/docker-entrypoint.sh"]
# does not matter your parameter $JAVA_OPTS wrapped as ${JAVA_OPTS}
CMD ["java", "$JAVA_OPTS", "-javaagent:/opt/newrelic/newrelic.jar", "-server", "-jar", "app.jar"]
with an ENTRYPOINT shell script below:
#!/bin/bash
set -e
source /work-dir/env.sh
exec "$#"
it will build the image correctly but print the error below during the run of container:
Error: Could not find or load main class $JAVA_OPTS
Caused by: java.lang.ClassNotFoundException: $JAVA_OPTS
instead, Java can read the command line parameters either through the command line or by _JAVA_OPTIONS environment variable. so, it means we can pass the desired command line parameters through _JAVA_OPTIONS without changing anything on Dockerfile as well as to allow it to be able to start as parent process of container for the valid docker signalization via exec "$#".
The below one is my final version of the Dockerfile and docker-entrypoint.sh files:
...
ENTRYPOINT ["/docker-entrypoint.sh"]
CMD ["java", "-server", "-jar", "app.jar"]
#!/bin/bash
set -e
source /work-dir/env.sh
export _JAVA_OPTIONS="-XX:+PrintFlagsFinal"
exec "$#"
and after you build your docker image and tried to run it, you will see the logs below that means it worked well:
Picked up _JAVA_OPTIONS: -XX:+PrintFlagsFinal
[Global flags]
int ActiveProcessorCount = -1 {product} {default}
Inspired on above, I did this:
#snapshot by default. 1 is release.
ENV isTagAndRelease=0
CMD echo is_tag: ${isTagAndRelease} && \
if [ ${isTagAndRelease} -eq 1 ]; then echo "release build"; mvn -B release:clean release:prepare release:perform; fi && \
if [ ${isTagAndRelease} -ne 1 ]; then echo "snapshot build"; mvn clean install; fi && \
.....
How can I get /etc/profile to run automatically when starting an Alpine Docker container interactively? I have added some aliases to an aliases.sh file and placed it in /etc/profile.d, but when I start the container using docker run -it [my_container] sh, my aliases aren't active. I have to manually type . /etc/profile from the command line each time.
Is there some other configuration necessary to get /etc/profile to run at login? I've also had problems with using a ~/.profile file. Any insight is appreciated!
EDIT:
Based on VonC's answer, I pulled and ran his example ruby container. Here is what I got:
$ docker run --rm --name ruby -it codeclimate/alpine-ruby:b42
/ # more /etc/profile.d/rubygems.sh
export PATH=$PATH:/usr/lib/ruby/gems/2.0.0/bin
/ # env
no_proxy=*.local, 169.254/16
HOSTNAME=6c7e93ebc5a1
SHLVL=1
HOME=/root
TERM=xterm
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/
/ # exit
Although the /etc/profile.d/rubygems.sh file exists, it is not being run when I login and my PATH environment variable is not being updated. Am I using the wrong docker run command? Is something else missing? Has anyone gotten ~/.profile or /etc/profile.d/ files to work with Alpine on Docker? Thanks!
The default shell in Alpine Linux is ash.
Ash will only read the /etc/profile and ~/.profile files if it is started as a login shell sh -l.
To force Ash to source the /etc/profile or any other script you want upon its invocation as a non login shell, you need to setup an environment variable called ENV before launching Ash.
e.g. in your Dockerfile
FROM alpine:3.5
ENV ENV="/root/.ashrc"
RUN echo "echo 'Hello, world!'" > "$ENV"
When you build that you get:
deployer#ubuntu-1604-amd64:~/blah$ docker build --tag test .
Sending build context to Docker daemon 2.048kB
Step 1/3 : FROM alpine:3.5
3.5: Pulling from library/alpine
627beaf3eaaf: Pull complete
Digest: sha256:58e1a1bb75db1b5a24a462dd5e2915277ea06438c3f105138f97eb53149673c4
Status: Downloaded newer image for alpine:3.5
---> 4a415e366388
Step 2/3 : ENV ENV "/root/.ashrc"
---> Running in a9b6ff7303c2
---> 8d4af0b7839d
Removing intermediate container a9b6ff7303c2
Step 3/3 : RUN echo "echo 'Hello, world!'" > "$ENV"
---> Running in 57c2fd3353f3
---> 2cee6e034546
Removing intermediate container 57c2fd3353f3
Successfully built 2cee6e034546
Finally, when you run the newly generated container, you get:
deployer#ubuntu-1604-amd64:~/blah$ docker run -ti test /bin/sh
Hello, world!
/ # exit
Notice the Ash shell didn't run as a login shell.
So to answer your query, replace
ENV ENV="/root/.ashrc"
with:
ENV ENV="/etc/profile"
and Alpine Linux's Ash shell will automatically source the /etc/profile script each time the shell is launched.
Gotcha: /etc/profile is normally meant to only be sourced once! So, I would advise that you don't source it and instead source a /root/.somercfile instead.
Source: https://stackoverflow.com/a/40538356
You still can try in your Dockerfile a:
RUN echo '\
. /etc/profile ; \
' >> /root/.profile
(assuming the current user is root. If not, replace /root with the full home path)
That being said, those /etc/profile.d/xx.sh should run.
See codeclimate/docker-alpine-ruby as an example:
COPY files /
With 'files/etc" including an files/etc/profile.d/rubygems.sh running just fine.
In the OP project Dockerfile, there is a
COPY aliases.sh /etc/profile.d/
But the default shell is not a login shell (sh -l), which means profile files (or those in /etc/profile.d) are not sourced.
Adding sh -l would work:
docker#default:~$ docker run --rm --name ruby -it codeclimate/alpine-ruby:b42 sh -l
87a58e26b744:/# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/ruby/gems/2.0.0/bin
As mentioned by Jinesh before, the default shell in Alpine Linux is ash
localhost:~$ echo $SHELL
/bin/ash
localhost:~$
Therefore simple solution is too add your aliases in .profile. In this case, I put all my aliases in ~/.ash_aliases
localhost:~$ cat .profile
# ~/.profile
# Alias
if [ -f ~/.ash_aliases ]; then
. ~/.ash_aliases
fi
localhost:~$
.ash_aliases file
localhost:~$ cat .ash_aliases
alias a=alias
alias c=clear
alias f=file
alias g=grep
alias l='ls -lh'
localhost:~$
And it works :)
I use this:
docker exec -it my_container /bin/ash '-l'
The -l flag passed to ash will make it behave as a login shell, thus reading ~/.profile