Scenario

A container named mem_test running from image myapp:mem contains a memory stress script at /app/stress_memory.sh. Currently, the container runs with unbounded memory and can consume as much RAM as available on the host, preventing the OOM (Out of Memory) killer from terminating it even when it allocates excessive memory.

Task

Apply 100MB memory limits to the container so that running the provided stress script causes the container to be OOM-killed. Stop the container, restart it with memory limits applied using the appropriate flags, run the stress script, and verify the container gets OOM-killed when the memory limit is exceeded by checking the OOM kill status.

_Note: The container mem_test and image myapp:mem with the stress script are already available.

Example

# Before (no memory limits)
$ docker inspect mem_test --format 'Memory: {{.HostConfig.Memory}}'
Memory: 0

$ docker inspect mem_test --format 'OOMKilled: {{.State.OOMKilled}}'
OOMKilled: false

# After (memory limits applied and stress script triggers OOM)
$ docker inspect mem_test --format 'Memory: {{.HostConfig.Memory}}'
Memory: 104857600

$ docker inspect mem_test --format 'OOMKilled: {{.State.OOMKilled}}'
OOMKilled: true

$ docker inspect mem_test --format 'ExitCode: {{.State.ExitCode}}'
ExitCode: 137

Step 1: Check current container status

docker ps

See if the container exists and its current state.

Step 2: Inspect current memory configuration

docker inspect mem_test | grep -i memory

Check if any memory limits are configured.

Step 3: Check OOM status before applying limits

docker inspect mem_test --format 'OOMKilled: {{.State.OOMKilled}}'

Should show false (no OOM has occurred).

Step 4: Check memory limit values

docker inspect mem_test --format 'Memory: {{.HostConfig.Memory}} MemorySwap: {{.HostConfig.MemorySwap}}'

Should show 0 (unlimited memory).

Step 5: Stop the container

docker stop mem_test

Stop to modify configuration.

Step 6: Remove the container

docker rm mem_test

Remove so we can recreate with memory limits.

Step 7: Start container with memory limits and stress script

docker run -d --name mem_test --memory=100m --memory-swap=100m myapp:mem /app/stress_memory.sh

Run stress script as main process with 100MB RAM limit and no swap.

Step 8: Inspect again

docker inspect mem_test --format 'Memory: {{.HostConfig.Memory}} MemorySwap: {{.HostConfig.MemorySwap}}'