How to pass runtime arguments for java native image

[zhoufenqin]

Env:
kpack 0.9.2
k8s

If I want to enable JFR with Native Image, then in the build phase, I will pass a build argument like BP_NATIVE_IMAGE_BUILD_ARGUMENTS="--no-fallback --enable-monitoring=jfr --enable-monitoring=jvmstat" .

In runtime, I should configure JFR -XX:+FlightRecorder -XX:StartFlightRecording="filename=recording.jfr" to enable JFR and start a recording

For an pod spec, it looks like

  spec:
      containers:
      - args:
        - -XX:+FlightRecorder
        - -XX:StartFlightRecording=filename=/tmp/troubleshooting/recording.jfr,dumponexit=true,duration=10s
        command:
        - /cnb/process/web

But I hope the argument can be passed in another way. Like in OpenJDK buildpack, we will set BPL_JFR_ENABLED = true, then -XX:StartFlightRecording=dumponexit=true,filename=/tmp/recording.jfr will be automatically injected into JAVA_TOOL_OPTION when starting the java process.

Not sure if there are similar operations in a native image, we can pass some runtime environment, then /cnb/process/web will pick up some env as runtime parameters?

Expected Behavior

we don't need to configure each args manually, just configure some BPL_ env to represent the runtime environments.

Current Behavior

we should define args for each native image feature

Possible Solution

Steps to Reproduce

Motivations

[dmikusa]

If the options to enable flight recorder are the same for native image, we could add the JFR helper for it too. If they are not the same, we'd need a new helper.

[zhoufenqin]

Great, thanks @dmikusa , I think it's different and the buildpack won't be put into runtime image /layers.

I think it's a general feature, some other features may also request for this. Like supporting heapdump also need a helper.

BTW, what are the plans for adding features to the buildpack? E.g. how long will the feature be realized?

[dmikusa]

BTW, what are the plans for adding features to the buildpack? E.g. how long will the feature be realized?

There is no roadmap like with a traditional product that you'd purchase. It's an OSS project, so it really depends on when someone that is interested in this feature contributes the code.