Hand on Labs [Introduction to Containers]
Tasks:
- Task 0: Prerequisites
- Task 1: Run simple containers
- Task 2: Package your custom application using Docker
- Task 3: Running your application on Kubernetes locally
Task 0: Prerequisites
First, you need to install Docker.
Install Docker Desktop on Mac
Docker Desktop is an easy-to-install application for your Mac, Linux, or Windows environment that enables you to build and share containerized applications and microservices.
It provides a simple interface that enables you to manage your containers, applications, and images directly from your machine without having to use the CLI to perform core actions.
What's included in Docker Desktop? What are the key features of Docker Desktop?
- Docker Engine
- Docker CLI client
- Docker Buildx
- Docker Compose
- Docker Content Trust
- Kubernetes
- Credential Helper
Docker Desktop works with your choice of development tools and languages and gives you access to a vast library of certified images and templates in Docker Hub. This enables development teams to extend their environment to rapidly auto-build, continuously integrate, and collaborate using a secure repository.
Then launch the Docker app and confirm your password for privileged access. (Might need a restart)
Run Docker Desktop Application
open /Applications/Docker.appRun a simple nginx container
- Check if Docker was installed successfully:
Chech your Version
docker version- Run the following command:
Command to pull a image of nginx from Docker Hub
docker run -d -p 80:80 --name webserver nginxWhen nginx:latest image could not be found locally, Docker automatically pulls it form Docker Hub.
You’ll notice a few flags being used. Here’s some more info on them:
- -d - run the container in detached mode (in the background)
- -p 80:80 - map port 80 of the host to port 80 in the container
- nginx - the image to use
-
Try to access a container on localhost:80 on your machine: http://127.0.0.1:80/
-
Check how long it will take to start a new container with a new image:
Run this command to create a new container
docker run -d -p 8080:80 --name webserver2 nginxThe image was downloaded already, so this container started faster.
- You can run bash commands inside a Linux container:
This command open an interactive console in the container
docker exec -it webserver /bin/bashDocker exec runs a command in a running container and the switch -it opens an interactive console
- Stop containers and remove the image:
Command to STOP containers before remove it
docker stop webserverdocker stop webserver2Command to REMOVE containers
docker rm webserverdocker rm webserver2Command to REMOVE IMAGES in Docker Hub
docker rmi webserverdocker rmi webserver2Package your custom application using Docker
You can create an image for your application by using Dockerfile. It contains a list of instructions to build images such as installing a package, downloading source code, using a base image.
- Create a new folder:
Create the directory
mkdir web-imageAccess to the directory
cd web-imageCreate a file for the example website:
code index.html<html>
<body>
<h1>Hello world</h1>
<p>This is a Talent-Academy Exercise</p>
</body>
</html>- Create a Dockerfile and add the following:
Dockerfile is a text file that contains a list of instructions needed to build a given image. For example: install a package, download source code, use a base image.
code DockerfileFROM ubuntu
RUN apt-get update
RUN apt-get install nginx -y
COPY index.html /var/www/html/
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]- FROM specifies the base image to use as the starting point for this new image you're creating.
- RUN Executes a command on top of an existing layer and creates a new resulting layer
- COPY Copies files and directories from a source (host executing build command) to a destination (Container image)
- Build Image
Run docker image build command to create a new Docker image using the instructions in your Dockerfile.
--tagallows us to give the image a custom name. It usually consists of your Docker Hub username, the application name, and a version..tells Docker to use the current directory as the build context
Be sure to include the period (.) at the end of the command.
docker build -t <image-name> --tag <yourusername>/<image-name>:1.0 .- (Optional) Push your image to Docker Hub
List local images:
docker imagesLog in to Docker Hub:
docker login --username <yourusername>Push the image to your repository in Docker Hub:
docker push <yourusername>/<image-name>:1.0