Selenium standalone in docker compose - killed by OS?

I suspect your selenium/standalone-chrome is implemented using Java technology.

And the container's JVM has a bounded max memory with JVM argument -Xmx2048m or similar value.

Research selenium JVM setup/configuration files.

What can happen is one or more of the options:

1. Container application crashed with out of memory, because its memory bound was reached. Solution: decrease JVM max memory bound to match container's max memory bound (maybe 2048m > 2g).

2. JVM application crashed with out of memory. Solution: increase JVM max memory bound to match container's max memory bound (maybe 2048m not sufficient for the task).

3. Container peaked its CPU utilization limit for a moment and crashed. I assume selenium implements massive parallelism (check its configuration). Solution: provide more compute power to the container, or decrease selenium parallelism functionality.

Note that periodic resource monitoring tools fail to identify peak resources stress. If the peak is momentary and sharp. So if the resources stress is building up gradually you can identify the breaking point.