Difference between revisions of "Docker"

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(Docker basics)
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https://www.docker.com/
 
 
Docker hub: https://hub.docker.com/
 
 
Docker is a popular open-source platform for building, shipping, and running applications in containers. Containers are lightweight and portable environments that allow you to run applications and services with their dependencies isolated from the underlying host system.
 
 
'''Docker images''' are static snapshots or templates of a specific environment that are used to create and run Docker containers. A '''Docker image''' is a lightweight, standalone, and read-only package that contains everything needed to run a piece of software, including the code, runtime, libraries, environment variables, and system tools. It is a snapshot or template of a specific environment that can be used to create and run containers. A '''Docker container''' is a running instance of an image.
 
 
Using Docker, developers can create containerized applications, package them with all the necessary dependencies, and ship them as a single unit that can be deployed on any system that supports Docker. Docker also provides a way to manage containerized applications at scale, with features such as container orchestration, automated builds, and version control.
 
 
Some of the benefits of using Docker include improved application portability, faster development cycles, and better resource utilization. With Docker, developers can focus on building and testing applications, while operations teams can easily deploy and manage them across different environments and infrastructure. [ChatGPT]
 
 
 
==Installation==
 
Last time I installed Docker and Docker Compose, I follwed ChatGPT and everything was perfect!
 
 
The official documentation to install it in Ubuntu is here: https://docs.docker.com/engine/install/ubuntu/
 
 
 
<br />
 
 
==Why use Docker==
 
* Capture all dependencies as code:
 
:* Python requerements
 
:* OS dependencies.
 
 
* Consistent dev and prod environment: You can use the same image for development and production. So you eliminate all the issues that can arrive when changing to another environment in production.
 
 
* Easier collaboration: When you share your code with other developers you can be sure it will work. You eliminate all dependencies issues in another developer's machines.
 
:* Different version of Python / Different version of databases / Different version of SDK.
 
 
 
<br />
 
==Docker basics==
 
 
<syntaxhighlight lang="bash">
 
docker --version
 
</syntaxhighlight>
 
 
 
Download Docker images from https://hub.docker.com/
 
<syntaxhighlight lang="bash">
 
docker pull postgres
 
docker pull mongo
 
</syntaxhighlight>
 
 
 
Create a new Docker container:
 
 
: In the case of the official MongoDB image, it is already built and available on Docker Hub, so you can directly pull and run the image:
 
: <syntaxhighlight lang="bash">
 
docker run --name my-mongo-container -d -p 27017:27017 mongo
 
</syntaxhighlight>
 
 
 
: The docker build command is used when you want to build a custom Docker image based on your specific requirements, using a Dockerfile. So it is used to add customizations or extend the functionality of the image.
 
: <code>Dockerfile</code>
 
: <syntaxhighlight lang="bash">
 
# Use the official MongoDB image as the base
 
FROM mongo
 
 
# Add a custom configuration file
 
COPY my-custom-config.conf /etc/mongodb.conf
 
 
# Expose a custom port (optional)
 
EXPOSE 27018
 
 
# Set an environment variable (optional)
 
ENV MY_VAR=my_value
 
 
# Run a custom command (optional)
 
CMD ["mongod", "--config", "/etc/mongodb.conf"]
 
</syntaxhighlight>
 
 
: <syntaxhighlight lang="bash">
 
docker build -t my-custom-mongo-image .
 
</syntaxhighlight>
 
 
: <syntaxhighlight lang="bash">
 
docker run --name my-custom-mongo-container -d -p 27018:27018 my-custom-mongo-image
 
</syntaxhighlight>
 
 
 
Show all the containers in our machine:
 
<syntaxhighlight lang="bash">
 
docker ps
 
docker ps -a
 
</syntaxhighlight>
 
 
We should be able to see the Postgres container running.
 
 
[[File:Output_of_the_dockerpa-a_command.png|1000px|thumb|center|Output of the docker pa -a command]]
 
 
 
Stop/Start a container:
 
<syntaxhighlight lang="bash">
 
docker stop INSERT_CONTAINER_ID_HERE
 
docker start c6f7dfc1a4c8
 
</syntaxhighlight>
 
Please note that the run command is used to create a new Docker container while the start command is used to run an existing container.
 
 
 
Remove a container:
 
<syntaxhighlight lang="bash">
 
docker rm c6f7dfc1a4c8
 
</syntaxhighlight>
 
Please note that before you can remove a Docker container, you must stop it.
 
 
 
Remove a Docker image:
 
<syntaxhighlight lang="bash">
 
docker rmi INSERT_IMAGE_ID_HERE
 
</syntaxhighlight>
 
Please note that before you can remove a Docker image, you must stop and remove all its associated containers.
 
 
 
<br />
 

Latest revision as of 13:57, 25 February 2026