A Simple Docker Compose Trick for Debugging Containers Stuck in a Restart Loop

When a Docker container is continuously restarting, you can't use docker exec because the container never stays in a running state long enough.

docker exec -it myapp sh

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You'll typically get:

Error response from daemon: Container <id> is restarting, wait until the container is running

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The Solution

Start a temporary container using the same Docker Compose service, but override its entrypoint with a shell.

docker compose run --rm --entrypoint sh <service-name>

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Example:

docker compose run --rm --entrypoint sh rusikapi

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Why It Works

This command creates a new container using the same:

• Image
• Environment variables
• Volumes
• Networks
• Service configuration

Instead of starting your application, it opens an interactive shell, allowing you to investigate the environment before anything crashes.

Common Debugging Tasks

Once inside the container, you can:

# Verify environment variables
printenv

# Inspect application files
ls -la

# Run Prisma migrations manually
npx prisma migrate deploy

# Start the application
npm run start

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This makes it much easier to identify startup failures, database connectivity issues, or configuration problems.

Takeaway

docker compose run --rm --entrypoint sh is a simple but effective debugging technique that every Docker Compose user should know.

docker compose run --rm --entrypoint sh <service-name>

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