Docker Build Exit Code 137 (OOM Killed) - Fix Out-of-Memory Builds

Exit code 137 is 128 + 9 - the process received SIGKILL. In CI that is almost always the out-of-memory killer terminating a build that exceeded the available memory.

What this error means

A RUN step or a container exits with code 137 and often the single word Killed. There is rarely a stack trace, because SIGKILL cannot be caught.

docker build output

#12 137.4 Killed
ERROR: process "/bin/sh -c npm run build" did not complete successfully: exit code: 137

Common causes

The build exceeded the memory limit

Webpack/bundler builds, large compiles, and test suites can spike past a runner’s memory ceiling. The cgroup OOM killer then terminates the heaviest process with SIGKILL.

A container memory limit is too low

If you pass --memory/-m or set a compose memory limit, exceeding it triggers the same kill at exit 137.

How to fix it

Give the build more memory

Run the job on a larger runner with more RAM.
Raise or remove an explicit container --memory limit if one is set.
For Node, cap the heap below the container limit with NODE_OPTIONS=--max-old-space-size=4096.

Reduce peak memory

Lower build parallelism (e.g. make -j2, Jest --maxWorkers=2).
Split a monolithic build/test step into smaller steps.
Avoid loading large datasets or source maps into memory during the build.

How to prevent it

Right-size runners for memory-heavy builds.
Set language heap limits relative to the runner memory.
Watch peak memory in CI so you catch growth before it OOMs.

Frequently asked questions

Is exit 137 always out of memory?

It means the process got SIGKILL. On memory-limited CI runners that is overwhelmingly the OOM killer, but it can also be an external watchdog or timeout --signal=KILL. Check the runner’s memory metrics or kernel log to confirm.