Why My Spark Container Keeps Exiting - Docker PID 1 and the Daemon Trap

The article provides an in-depth explanation of why Spark containers might unexpectedly exit when using start-master.sh to start a Spark Master process within Docker. The core issue lies in how Docker manages the lifecycle of its containers based on PID 1 (the primary process). Here's a summary and key takeaways from the article:

Key Points

Problem: Background Processes and Container Lifecycle

• Docker Containers Exit When PID 1 Exits: This is a fundamental behavior of Docker. If the main process (PID 1) terminates, the container stops.
• start-master.sh Backgrounds Spark Master Process: The script start-master.sh runs the Spark Master in the background and then exits immediately. Since the startup script is PID 1, its exit causes the container to terminate.

Solutions

The article provides several solutions to ensure that a foreground process (which never returns) acts as PID 1:

1. Fix A: tail -f /dev/null

   • Run tail -f /dev/null as PID 1 to keep the container running indefinitely.
   • Use docker exec to submit jobs manually.

2. Fix B: Directly Run Spark Master Class

Read the full article at DEV Community

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