Debug Quarkus app packaged with quarkus-container-image-jib - quarkus

Question

I would like to run the same image in our dev, staging and production environments. For our dev environment I would like to be able to connect a debugger.
I build the image for our Quarkus app like this (mvn package):
<dependencies>
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-container-image-jib</artifactId>
</dependency>
...
</dependencies
<properties>
<quarkus.container-image.build>true</quarkus.container-image.build>
<quarkus.jib.ports>8080,5005</quarkus.jib.ports>
<quarkus.container-image.image>...</quarkus.container-image.image>
...
</properties>
<build>
<plugins>
<plugin>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-maven-plugin</artifactId>
<version>1.12.1.Final</version>
<executions>
<execution>
<goals>
<goal>build</goal>
</goals>
<phase>package</phase>
</execution>
</executions>
</plugin>
</plugins>
</build>
Is it possible to start the application in debug mode while otherwise running with prod profile? Passing JAVA_OPTIONS=-Ddebug=true via an environment variable to the container causes a Exception in thread "main" java.nio.file.NoSuchFileException: /work/lib/deployment/deployment-class-path.dat.
If not, what would be the appropriate way to accomplish such a setup?

Answer 1

There are a few ways to do that, but they all rely on the fact that in Quarkus you can control Jib to use whatever launch script you want for the container image.
By default the container-image is created with a minimal java -jar ... style ENTRYPOINT, but that can be changed using the quarkus.jib.jvm-entrypoint.
If you use the default base image which already contains a run-java.sh script that provides a host of options (see https://hub.docker.com/r/fabric8/java-alpine-openjdk11-jre#startup-script-run-javash) then what you are trying to accomplish could be done by setting the following in application.properties:
quarkus.jib.jvm-entrypoint=/deployments/run-java.sh
quarkus.jib.environment-variables."JAVA_APP_DIR"=/work # this is needed so the script knows where the Quarkus jar is
Then launch the application using:
docker run --rm -p 8080:8080 -p 5005:5005 -e JAVA_DEBUG=true gandrian/getting-started:1.0.0-SNAPSHOT
Now the application will have the debug port open (but won't suspend) and you can connect to it with a debugger

Answer 2

It is possible to make the same Quarkus image open a debug port in your Kubernetes Deployment, i.e. without rebuilding the image only for debugging.
When using JIB with a Red Hat UBI base image, e.g. quarkus.jib.base-jvm-image=registry.access.redhat.com/ubi8/openjdk-11-runtime:1.14 , this works by overriding the container command in your Deployment K8S descriptor like this:
containers:
- name: your-app
image: your-app-image
command: ["java"]
args: ["-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005", -Djava.util.logging.manager=org.jboss.logmanager.LogManager", "-jar", "quarkus-run.jar"]
This overrides the Docker image's Entrypoint, which looks like this (gleaned from docker inspect):
"Entrypoint": [
"java",
"-Djava.util.logging.manager=org.jboss.logmanager.LogManager",
"-jar",
"quarkus-run.jar"
],
This might work for other base images and container builders other than JIB as well, if the Entrypoint is the same.
For the records, the Quarkus image Entrypoint with JIB seems to be determined programmatically here: https://github.com/quarkusio/quarkus/blob/c28a72b63104d8856fac1481b107c9f9ff3e7f1a/extensions/container-image/container-image-jib/deployment/src/main/java/io/quarkus/container/image/jib/deployment/JibProcessor.java#L390