Docker Create Container

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In this quick guide, we will see how to create a Docker container from a Docker image.

Understanding docker create Command

Most Docker users are familiar with the docker run command, which creates and starts a container in a single step. However, Docker provides a two-step approach as well, allowing for more granular control:

  • docker create: This initializes the container. 
  • docker start: This sets the container in motion. 

In essence, docker creates a container instance from a specified image without actually starting it. 

The Syntax: 

The basic structure of the docker create command is:

docker create [OPTIONS] IMAGE [COMMAND] [ARG...]

Practical Use-Cases

Why might you use docker create instead of docker run? 

Configuration Control: Sometimes, you might want to create a container with specific configurations and only start it later once everything is set. 

Batch Operations: If you need to create multiple containers simultaneously and start them later based on certain conditions or schedules. 

Testing: It allows for testing container creation scripts without actually running the containers.

Examples in Action

Basic Container Creation: 

To create a container from an image named myapp:

docker create myapp

This command will output a long container ID, which you can use to start, inspect, or manage the container later.

Naming Your Container: 

Assigning a name to your container can make it more recognizable:

docker create --name my_container_name myapp

Using the --name option, we can give a name to the container that we create.

Specifying Environment Variables:

You might need to provide specific environment variables for your application:

docker create -e "MY_VAR=value" myapp

Binding Ports: 

To expose a container's port to the host, use the -p option:

docker create -p 8080:80 myapp

This binds the host's 8080 port to the container's 80 port. 

Mounting Volumes: 

To persist data or share directories between the host and container:

docker create -v /host/directory:/container/directory myapp

Starting the Created Container: 

After creating your container using the docker create command, you can start it using:

docker start container_id_or_name

For example, you can run the container named myapp:

docker start myapp

Conclusion

While docker run offers a swift and convenient way to get containers up and running, docker create provides an avenue for those seeking an added layer of control in their container lifecycle. Happy Dockering!

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