I have a very simple java jar application that fetches DB properties from the env variables. I`ve dockerized it and migrated to Kubernetes. I also created a config map and secret with parameters to my DB - so I have access to these properties in the container. Is it possible to fetch all properties and inject it in Dockerfile? How can I do it?
FROM openjdk:8-jre
ADD target/shopfront-0.0.1-SNAPSHOT.jar app.jar
EXPOSE 8010
ENTRYPOINT ["java","-Ddb.host=**value-from-env-variable**","-jar","/app.jar"]The array or "exec form" of entrypoint uses exec to run the specified binary rather than a shell. Without a shell the string $DB_HOST is passed to your program as argument.
ENTRYPOINT java -Ddb.host="${DB_HOST}" -jar /app.jarIf your startup get more complex you can also use an ENTRYPOINT script.
ENTRYPOINT ["/launch.sh"]Then launch.sh contains:
#!/bin/sh -uex
java -Ddb.host="${DB_HOST}" -jar /app.jarAs I understand you need to fetch parameters from config map and secret and set them as environment variables in your container. Furtunately it's quite nicely described in Kubernetes documentation.
Have a look at below links:
To sum up, such resources need to be just defined in Pod's configuration.
You can use them like this
ENTRYPOINT ["java", "-jar", "-Ddb.host=${DB_HOST}", "/app.jar"]where DB_HOST should be defined in config map you have created.
I have tried this in my Spring Boot Application for setting Spring Profile.