Docker Lesson‐1 ‐ Introduction - MantsSk/CA_PTUA14 GitHub Wiki
Docker is a popular containerisation platform that allows developers to easily create, deploy, and run applications in isolated containers. It uses operating system-level virtualisation to create lightweight and portable containers that can run on any system that supports Docker. Each container includes all the necessary dependencies and libraries required to run the application, making it easy to build and deploy applications across different environments. Docker also provides a centralised registry called Docker Hub, where developers can share and distribute their container images with the wider community. With Docker, developers can streamline the application development process, increase productivity, and reduce infrastructure costs.
For Linux users, please go there: https://docs.docker.com/engine/install/ubuntu/
For Windows users , please go there: https://docs.docker.com/desktop/install/windows-install/
For macOS users , please go there: https://docs.docker.com/desktop/install/mac-install/
Docker images are a key concept in Docker, a popular platform for building, packaging, and deploying software applications. In simple terms, a Docker image is a lightweight, standalone, and executable package that contains all the necessary files, dependencies, and configurations required to run an application.
An image is created by specifying a series of instructions in a Dockerfile, which is a text file that contains the commands to build the image. These instructions typically include things like installing packages, copying files, and setting environment variables. Once the Dockerfile is built, the resulting image can be stored in a Docker registry or repository, such as Docker Hub or a private registry.
Images are designed to be portable and can be run on any host that supports Docker. When an image is executed, it creates a container, which is a lightweight, isolated runtime environment that runs the application. Multiple containers can be created from the same image, each with its own isolated runtime environment, allowing applications to be easily scaled and managed.
Overall, Docker images provide a simple and efficient way to package, distribute, and run applications, making it easier to develop, deploy, and manage software in a variety of environments.
Open up a terminal or command prompt and type in the following command to download a Docker image:
docker pull <image_name>
Replace <image_name> with the name of the image you want to download. For example, if you want to download the official nginx image, you would type:
docker pull python
Once the image is downloaded, you can start a container from it by typing:
docker run <image_name>
docker run ngix
You can also specify additional options when starting a container. For example, to start a container and map a local port to the container's port 80 (so you can access the web server from your browser as for example), you would type:
docker run -p 8080:80 nginx
To list all images you have already downloaded:
docker image list
To delete the image from the list:
docker image rm <image_id>
or
docker rmi <image_id>
##Containers
As already mentioned, a container is a lightweight, standalone, and executable package that includes everything needed to run an application, such as code, runtime, libraries, and system tools. Containers allow you to run your applications in an isolated environment that has all the necessary dependencies and configurations, without affecting the host system.
Run a Docker container:
docker run <image_name>
List all running containers:
docker ps
Stop a running container:
docker stop <container_id>
Remove a stopped container:
docker rm <container_id>
View logs from a container:
docker logs <container_id>
Start a stopped container:
docker start <container_id>
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Task Nr.1: Go and find the latest mongo db image and install/ run it.
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Task Nr.2: Install several other images, and try to use all the commands from the examples.