username

password

In this course, you’ll learn about containers, creating images, containerizing applications, and effectively deploying Docker in real-world scenarios.

Nigel Poulton - Docker Deep Dive- Part 1.png

test2.tar.gz

run_web_app

dockergit-copy

DockerfileUpdateNewVersion

DockerfileUpdateNewVersion_ReflectChanges

Containerisation_the Application  

User_testing

DDD_2

Containers have revolutionized the IT world, making it difficult to know where to begin. This course will take you from basics to proficiency step by step.
You’ll start by learning the basics of containers and how they work. Then, you’ll explore key concepts like images and the Docker engine. With the basics out of the way, you’ll learn how to containerize and run an application. After completing this course, you’ll be ready to use Docker in the real world.

Docker Guide for Beginners

# Inspecting container processes
Most containers only run a single process, which is the container’s main app process and always `PID 1`. Run a `ps` command to see the processes running in the container. For these commands to work, we’ll need to be connected to the session from the previous lesson.



$ docker exec -it webserver sh

/src # ps
PID   USER     TIME  COMMAND
    1 root      0:00 node ./app.js
   13 root      0:00 sh
   22 root      0:00 ps

The output shows three processes:
- `PID 1` is the main application process running the Node.js web app
- `PID 13` is the shell process our interactive session is connected to.
- `PID 22` is the `ps` command we just ran.

> **Note:** The PID of the processes may vary.

The `ps` process is terminated as soon as it displays the output, and the `sh` process will terminate when we exit the session. This means the only long-running process is `PID 1` running the Node app.

If we stop the container’s main process (`PID 1`), we’ll also terminate the container. This is because containers only run while their main process is running—when that process is no longer running, there’s no reason for the container to run. 

## Exiting with terminating
Type `exit` to quit the session and return to the local terminal. Run another `docker exec` command without specifying the `-it` flags. This will remotely execute the command without creating an interactive session. The format of the command is `docker exec <container> <command>`, and it will only work if the command we’re executing is installed in the container.



Learn about the processes associated with the containers. 

About the Course

An Overview of Containers

Docker and Container-Related Standards and Projects

The Big Picture

The Docker Engine

Working with Images

Working with Containers

Containerizing an Application

Conclusion

Appendix: Getting Docker

Container Processes

Inspecting container processes