问题
Normally when I create Docker image I do something like this:
FROM openjdk:15-jdk-slim
ARG version=undefined
LABEL version=${version}
WORKDIR /
COPY build/libs/v2t-api-$version.jar /v2t-api.jar
USER nobody
VOLUME ["/tmp"]
EXPOSE 8080
EXPOSE 8081
ENTRYPOINT ["sh", "-c", "exec java ${JAVA_OPTS} -jar v2t-api.jar"]
So, when I start my container in for example kubernetes I can set JAVA_OPTS which defines how many memory is available for heap or how many CPUs are actually there.
Packaging OCI Images using built-in gradle plugin from Spring Boot looks interesting, but I can't find how to do something similar in buildpacks - I would like to set some flags to java process, so how do I do that?
回答1:
According to the Paketo.io docs there are 2 kinds of environment variables one could pass to the Paketo build:
- Build-time Environment Variables
- Runtime Environment Variables
If I understand your question correctly you're looking for a way to configure Runtime Environment variables (2.). In order to do that you need to pass environment variables to the container running your app (which was build by CNB/Paketo before) e.g. by using the --env flag. As the docs state
Users may configure runtime features of the app image by setting environment variables in the app container. The names of variables accepted by buildpack-provided runtime components [..] are prefixed with BPL_ or have well-known conventional meanings outside of Paketo (e.g JAVA_TOOL_OPTIONS).
So for example if you build an container image called v2t-api:latest, then you can run your container with:
docker run --env "JAVA_TOOL_OPTIONS=-Xms1024m -Xmx2048m" v2t-api:latest
I can advice you to switch from JAVA_OPTS to JAVA_TOOL_OPTIONS, because your application won't receive the sigterm in case of a graceful shutdown & your app wouldn't be shutdown correctly (see this so answer for more details).
来源：https://stackoverflow.com/questions/64964709/how-to-pass-flags-to-java-process-in-docker-contatiner-built-by-cloud-native-bui