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So I know you can pass Environment variables to a docker container using -e like:
docker run -it -e "var=var1" myDockerImage
But I need to pass a System Property to a docker container, because this is how I run my JAR:
java -Denvironment=dev -jar myjar.jar
So how can I pass a -D System property in Docker? Like:
docker run -it {INSERT Denvironment here} myDockerImage
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With a Command Line Argument The command used to launch Docker containers, docker run , accepts ENV variables as arguments. Simply run it with the -e flag, shorthand for --env , and pass in the key=value pair: sudo docker run -e POSTGRES_USER='postgres' -e POSTGRES_PASSWORD='password' ...
Using docker-compose , you can inherit env variables in docker-compose. yml and subsequently any Dockerfile(s) called by docker-compose to build images. This is useful when the Dockerfile RUN command should execute commands specific to the environment.
Pass variables into Dockerfile through Docker Compose during build. If you want to pass variables through the docker-compose process into any of the Dockerfiles present within docker-compose. yml , use the --build-arg parameter for each argument to flow into all of the Dockerfiles.
How to set the Environment variable in the container? To set an environment variable you should use flag -e while using docker run or docker-compose command. Environment file - If the environment variable is not overridden by docker-compose.
Use the variable you passed into the container on the java command:
docker run -it -e "ENV=dev" myDockerImage
java -Denvironment=$ENV -jar myjar.jar
One more way to do it, if running under Tomcat, is setting your system variables in your Dockerfile using ENV JAVA_OPTS like this:
ENV JAVA_OPTS="-Djavax.net.ssl.trustStore=C:/tomcatDev.jks -D_WS_URL=http://some/url/"
Hope it helps!
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