Fix container signal handling so the JVM receives SIGTERM for clean shutdown

[GreicodexJM]

Problem

The Docker image's ENTRYPOINT uses the shell form, so PID 1 inside the container is /bin/sh -c, not the OpenAS2 JVM. SIGTERM sent by docker stop (or by Kubernetes on pod termination) is delivered to the shell, which does not forward it. As a result:

• The JVM's registered shutdown hook never runs — modules (including DbTrackingModule with the embedded H2 database) are never stopped cleanly.
• Every container stop waits out the full grace period (10s by default) and ends in SIGKILL.
• This is also what the Docker build check JSONArgsRecommended warns about on the current Dockerfile.

Fix

Three small changes so the signal chain reaches the JVM:

1. Dockerfile — exec-form ENTRYPOINT ["/opt/openas2/bin/start-container.sh"] (exec form cannot expand variables; the path is already fixed by ENV OPENAS2_BASE in the same Dockerfile, and the scripts keep using the variable at runtime).
2. start-container.sh — exec the startup script instead of forking it.
3. start-openas2.sh — exec java in the foreground (non-daemon) branch so the JVM ends up as the final process. Daemon mode (OPENAS2_AS_DAEMON=true) is unchanged, and the exit code behavior of the foreground branch is preserved (exec makes the script's exit status the JVM's exit status).

Verification (on the 4.8.2 image)

Before:

• docker stop takes 10.2s (full grace period, then SIGKILL)
• No shutdown messages in the logs

After:

• ps inside the container shows PID 1 = java
• docker stop completes in ~0.2s
• Logs show the shutdown hook running:

[Thread-0] INFO  org.openas2.processor.DefaultProcessor - DbTrackingModule stopped.
[Thread-0] INFO  org.openas2.processor.DefaultProcessor - AS2ReceiverModule stopped.
[Thread-0] INFO  org.openas2.processor.DefaultProcessor - AS2MDNReceiverModule stopped.
[Thread-0] INFO  org.openas2.processor.DefaultProcessor - DirectoryResenderModule stopped.
[Thread-0] INFO  org.openas2.processor.DefaultProcessor - 4 active module(s) stopped.
[Thread-0] INFO  org.openas2.app.OpenAS2Server - OpenAS2 has shut down

The docker build check warning JSONArgsRecommended is also gone.

[uhurusurfa]

👍