I have a Dockerfile looks like below:
FROM tomcat:9.0.12-jre8
EXPOSE 8080
COPY app.war "$CATALINA_HOME"/webapps
I need to set some JVM properties as below:
-DTOMCAT=Y
-Doracle.server=1234
-Doracle.url=1234
-Doracle.password=1234
...
How do I add these properties in Dockerfile?
You can simply set the JAVA_OPTS value to the one you need at build time, in your Dockerfile :
ENV JAVA_OPTS="-DTOMCAT=Y -DOracle.server=1234 [...]"
You may also simply set it a runtime if you don't modify the CMD from the official tomcat image:
$ docker run -e JAVA_OPTS="-DTOMCAT=Y -DOracle.server=1234 [...]" your_image:your_tag
See: https://github.com/docker-library/tomcat/issues/8
Considering the options you're providing in your example, it would be better to opt for the second version (host, port and password information should not be left in a Docker image, from a security standpoint).
If you're only providing minimal requirements, resource-wise, for your application, this could live in the Dockerfile.
The use case you show seems more like environment variables. You can have your application read those values from env variables and you can set them at runtime.
$ docker run --env MYVAR2=foo
