Complete Guide: Access Docker Container Shell with docker-compose

You can access a Docker container’s interactive shell using docker-compose exec with the -it flags. For your WordPress setup, run docker-compose exec -it your_container_name bash to start an interactive bash shell inside the container, allowing you to navigate the directory structure and inspect files.

Contents

• Using docker-compose exec for Interactive Access
• Alternative Methods for Container Access
• Common Issues and Troubleshooting
• Practical Examples for WordPress Containers
• Best Practices for Container Inspections

Using docker-compose exec for Interactive Access

The most common and recommended method to access a container’s shell is using the docker-compose exec command with the appropriate flags. The basic syntax is:

docker-compose exec -it <container_name> <shell_command>

Key components of this command:

• -i or --interactive: Keeps STDIN open even if not attached
• -t or --tty: Allocates a pseudo-TTY
• <container_name>: The name of your service as defined in docker-compose.yml
• <shell_command>: Typically bash, sh, or your preferred shell

For your WordPress setup, if your service is named wordpress, you would use:

docker-compose exec -it wordpress bash

If you’re unsure about your container names, you can list your running services with:

docker-compose ps

This will show you all services defined in your docker-compose.yml file that are currently running.

Alternative Methods for Container Access

While docker-compose exec is the preferred method, there are several alternatives you should be aware of:

Using docker-compose run

The docker-compose run command creates a new container from your service:

docker-compose run --rm -it wordpress bash

• --rm: Automatically removes the container when you exit
• --service-ports: Publishes all service’s ports to the host

This is useful when you want a clean environment without the existing container’s state.

Using docker exec

If you prefer not to use docker-compose, you can use the native Docker command:

docker exec -it <container_id_or_name> bash

First, find your container ID:

docker ps

Then use the ID or name in the exec command.

Attaching to a Running Container

You can also attach to a running container:

docker attach <container_id_or_name>

However, this attaches you to the main process of the container, which may not be what you want for shell access.

Common Issues and Troubleshooting

Container Not Found Error

If you get “No such container” errors:

• Verify the container name using docker-compose ps
• Check your docker-compose.yml file for the correct service name
• Ensure the container is actually running

Shell Not Available

If you get “command not found” for bash:

docker-compose exec -it wordpress sh

Many minimal Docker images don’t include bash by default and use sh instead.

Permission Issues

If you encounter permission problems:

docker-compose exec -it --user root wordpress bash

This switches to root user inside the container for elevated permissions.

TTY Allocation Errors

If you see TTY allocation errors:

docker-compose exec -it wordpress bash

The -t flag may not work in all environments. Try without it if you encounter issues:

docker-compose exec -i wordpress bash

Practical Examples for WordPress Containers

Accessing WordPress Container

For a typical WordPress setup with docker-compose:

version: '3'
services:
  wordpress:
    image: wordpress:latest
    container_name: wordpress_container
    ports:
      - "8080:80"
    volumes:
      - wordpress_data:/var/www/html

Access the WordPress container:

docker-compose exec -it wordpress bash

Exploring WordPress File Structure

Once inside the container:

pwd                    # Should show /var/www/html
ls -la                 # List all files including hidden ones
find . -name "*.php"   # Find all PHP files

Checking Configuration Files

Inspect WordPress configuration:

cat wp-config.php      # View WordPress configuration
ls -la wp-content/     # Check WordPress content directory

Database Access

If you have a separate database service:

docker-compose exec -it mysql bash
mysql -u root -p       # Access MySQL database

Navigating Between Containers

Switch between different services:

exit                   # Exit current container
docker-compose exec -it phpmyadmin bash  # Access another service

Best Practices for Container Inspections

Read-Only Access

For inspection without modification:

docker-compose exec -it --user nobody wordpress sh

This runs commands as a non-privileged user.

Using Specific Shell Commands

Instead of full interactive shell, you can run specific commands:

docker-compose exec wordpress ls -la /var/www/html
docker-compose exec wordpress cat /etc/os-release

Persistent Shell Sessions

For longer inspection sessions, consider using screen or tmux inside the container:

docker-compose exec -it wordpress bash
apt-get update && apt-get install -y tmux
tmux new -s inspection

Container State Preservation

Be aware that some containers may have ephemeral filesystems. For WordPress:

• Check mounted volumes first
• Look at /var/www/html for WordPress files
• Database data is typically in separate volumes

Exit Gracefully

Always exit your shell properly:

exit

Or use Ctrl+D to ensure clean detachment from the container.

Sources

1. Official Docker Compose Documentation - Exec command
2. Docker Documentation - docker exec command
3. WordPress Docker Documentation
4. Docker Best Practices - Interactive shells
5. Docker Compose Reference Guide - Service configuration

Conclusion

Accessing a Docker container’s shell with docker-compose is straightforward using the exec command with the -it flags. For your WordPress setup, simply run docker-compose exec -it wordpress bash to start an interactive shell where you can explore the file system and inspect files. Remember that some minimal images may use sh instead of bash, so be prepared to try both shells. Always use docker-compose ps to verify your service names and container statuses before attempting to access them. These techniques will help you effectively inspect and debug your Dockerized applications while maintaining the benefits of containerization.