Troubleshooting Docker Container Exit Code 0 and Dependency Failures

Use this when a Docker container exits with code 0 but the service was expected to stay running.

Quick Read

Symptom: Use this when a Docker container exits with code 0 but the service was expected to stay running.
Check first: Confirm Docker Engine version, compose plugin version, current context, and whether the command is running as the expected user.
Risk: Changes system state

Symptoms

Docker container fails to start due to dependency issues, resulting in an exit code of 0 and continuous restarting.

Environment

Docker on Linux-based systems

Most Likely Causes

The container may have dependencies that are not met, or there may be misconfigurations in the Docker Compose file or Dockerfile that prevent the container from starting properly.

What to Check First

Confirm Docker Engine version, compose plugin version, current context, and whether the command is running as the expected user.
Inspect container state, image tags, volumes, networks, and registry authentication before deleting or recreating anything.
Check whether the failure is image build, container startup, runtime health, networking, or registry access.

Fix Steps

Check Docker Container Logs
Examine the logs of the Docker container to identify any errors or messages that indicate why the container is failing.
Safe to run: read-only
```
docker logs <container_name_or_id>
```
Inspect Docker Compose Configuration
Review the Docker Compose file for any misconfigurations or missing dependencies that could prevent the container from starting.
Safe to run: read-only
```
cat docker-compose.yml
```
Verify Dependency Services
Ensure that all services that the container depends on are running and healthy. Use the following command to check the status of all containers.
Safe to run: read-only
```
docker ps -a
```
Check Health Checks
If health checks are defined in the Dockerfile or Docker Compose, verify that they are configured correctly and that the container meets the health criteria.
Safe to run: read-only
```
docker inspect --format='{{json .State.Health}}' <container_name_or_id>
```
Review Dockerfile for Errors
Examine the Dockerfile for any syntax errors or incorrect commands that could lead to the container exiting immediately.
Example pattern only. Adjust for your environment before running.
```
cat Dockerfile
```
Test Container in Isolation
Run the container in isolation without dependencies to see if it starts successfully. This helps to identify if the issue is with the container itself or its dependencies.
Changes system state: review before running
```
docker run --rm -it <image_name>
```
Check Resource Limits
Ensure that the container is not being killed due to resource limits (CPU, memory). Check the Docker daemon logs for any OOM (Out of Memory) messages.
Safe to run: read-only
```
journalctl -u docker.service
```
Restart Docker Service
If the issue persists, try restarting the Docker service to clear any potential transient issues.
Changes system state: review before running
```
sudo systemctl restart docker
```

Validation

The affected container reaches the intended running or completed state with the expected exit code.
Application logs show normal startup and the health check reports healthy where one exists.
A clean shell or CI run repeats the successful Docker operation without relying on stale local state.

Logs to Check

docker logs for the affected container.
docker inspect output for state, mounts, environment, networks, and health status.
Docker daemon logs or registry authentication logs when pulls, pushes, or login are involved.

Rollback and Escalation

Keep the previous image tag and compose file before changing runtime settings.
Do not remove named volumes until data ownership and backup status are confirmed.
Revert to the previous image, compose file, credential helper, or network definition if validation fails.

Escalate When

Escalate if the same error persists after rollback and a clean retry from the original failing path.
Escalate if logs show authorization, data loss, certificate, replication, or production availability risk outside the local service owner scope.

Edge Cases

If the container relies on external services (like databases), ensure those services are reachable and properly configured.
Check for network issues that might prevent the container from accessing required services.

Notes from the Field

Container exit code 0 is often a workload design signal, not always a crash. Confirm whether the process is meant to stay resident.
Authentication and credential-helper fixes should be tested with the same user account that runs builds or services.