EC
OOMKilled
DockerERRORCommonRuntimeHIGH confidence

Container killed due to out of memory

What this means

This status indicates that the container was terminated by the Linux kernel's Out Of Memory (OOM) killer. This happens when the container tries to consume more memory than its allocated limit, forcing the system to reclaim memory to prevent instability.

Why it happens
  1. 1Container memory limit is set too low for the application's workload.
  2. 2The application running inside the container has a memory leak.
  3. 3The host machine itself is running low on available physical memory.
  4. 4A sudden, temporary spike in traffic or processing caused a legitimate surge in memory usage.
How to reproduce

A Node.js application container attempts to allocate memory beyond its 256MB limit, triggering the OOM killer.

trigger — this will error
trigger — this will error
# Run a container with a restrictive memory limit
docker run --name memory-hog --memory=256m -d your-app-image
# Let the app run and exceed its memory limit...
# Check the container's state to see if it was OOMKilled
docker inspect memory-hog --format="{{json .State}}"

expected output

{
  "Status": "exited",
  "Running": false,
  "Paused": false,
  "Restarting": false,
  "OOMKilled": true,
  "Dead": false,
  "Pid": 0,
  "ExitCode": 137,
  "Error": "",
  "StartedAt": "...",
  "FinishedAt": "..."
}

Fix 1

Increase the Container Memory Limit

WHEN When the application legitimately requires more memory for its workload.

Increase the Container Memory Limit
# Increase memory limit to 512MB
docker run --memory=512m your-app-image

Why this works

This directly allocates more memory to the container, providing more headroom before the OOM killer is invoked.

Fix 2

Profile and Fix Application Memory Leaks

WHEN When memory usage continually grows over time without stabilizing.

Profile and Fix Application Memory Leaks
# Monitor real-time memory usage of a container
docker stats your-container-name --no-stream

Why this works

Using tools like 'docker stats' or language-specific profilers helps identify parts of the application that are not releasing memory, allowing you to fix the underlying code.

Fix 3

Enable Swap Memory

WHEN To provide a buffer for temporary memory spikes, but not as a fix for leaks.

Enable Swap Memory
# Allow the container to use up to 1GB of swap
docker run --memory=512m --memory-swap=1g your-app-image

Why this works

This allows the container to use disk-based swap space when it runs out of physical RAM, which is slower but can prevent termination during brief spikes.

What not to do

✕ Remove the memory limit entirely in a production environment.

An unlimited container with a memory leak can consume all host memory, potentially crashing the host and all other containers running on it.

Sources

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