Difference Between `docker run` and `docker start`

In Docker, both docker run and docker start are commands used to manage containers, but they serve different purposes and are used in different contexts. Understanding the distinction between these two commands is essential for effectively managing your Docker containers.

1. Overview of `docker run`

The docker run command is used to create and start a new container from a specified image. This command combines the functionalities of creating a container and starting it in one step. When you run this command, Docker performs the following actions:

• Creates a new container from the specified image.
• Allocates a filesystem for the container.
• Sets up networking for the container.
• Starts the container and executes the specified command.

Example of `docker run`

Here’s an example of using docker run to create and start a new Nginx container:

docker run -d -p 8080:80 nginx

In this command:

• -d: Runs the container in detached mode (in the background).
• -p 8080:80: Maps port 80 of the container to port 8080 on the host.
• nginx: Specifies the image to use for creating the container.

2. Overview of `docker start`

The docker start command is used to start an existing, stopped container. This command does not create a new container; instead, it starts a container that has already been created and is in a stopped state. When you run this command, Docker performs the following actions:

• Starts the specified stopped container.
• Restores the container's state to the point where it was stopped.

Example of `docker start`

Here’s an example of using docker start to start a previously created container:

docker start <container_id>
</container_id>

In this command:

• <container_id>: Replace this with the actual ID or name of the stopped container you want to start.

3. Key Differences

4. Conclusion

In summary, docker run is used to create and start a new container from an image, while docker start is used to start an existing stopped container. Understanding the differences between these two commands is crucial for effectively managing your Docker containers and workflows.