Containers with Docker

The goals of this lab are to:

Useful links

In the hello-world-web-app directory, you will find:

A server.js which is the code for a simple "Hello World" Node.js web app
A package.json that describes the Node.js web app and its dependencies
A Dockerfile which describes the previous Node.js web app as a Docker container

Before you can start the lab, you have to:

Install Docker following the instructions depending on your OS.
Make sure your docker installation in working properly by running the following command in a terminal (Cmd or Powershell for Windows):
```
docker run hello-world
```

Clone the lab repository to your computer:

 git clone https://github.com/leopaul36/dsti-fall-devops-docker.git

Open the hello-world-web-app directory in the repository and check out the server.js, package.json and Dockerfile files
Check out the explanations for each line in the Dockerfile from the documentation
Build the docker container
Open a terminal (Cmd or Powershell for Windows)
Navigate to the hello-world-web-app directory in the cloned repository
Run the following command:
```
docker build -t hello-world-webapp-container .
```
Don't forge the . at the end of the command. It is here to tell Docker it should look for a Dockerfile in the current directory -t tags the built container with the name you want, here hello-world-webapp-container
Check if your Docker container appears in the local Docker images:
```
docker images
```

Run the container with the following command:
```
docker run -p 12345:8080 -d hello-world-webapp-container
```
1. -p maps a port on your local machine to a port inside the container
2. -d makes the container run in background
Check if the container is running (and save the container ID) with the following command:
```
docker ps
```
Open your web browser and go to http://localhost:12345
Print the logs of the container with:
```
docker logs <container id>
```
Stop the container with:
```
docker stop <container id>
```

Modify the message printed in the server.js (you can add your name for example)
Rebuild the Docker container (with a different name) with this modified code and see if you can run it and navigate to the web app in your browser
Register on Docker Hub

Tag your container with the following command:

docker tag hello-world-webapp-container <docker-account-name>/<custom-image-name>

Push the docker image to Docker Hub:

docker push <docker-account-name>/<custom-image-name>

Ask a classmate to retrieve your Docker container and run it:

docker pull <docker-account-name>/<custom-image-name>
docker run -p 12345:8080 -d <docker-account-name>/<custom-image-name>

Docker compose should be included in your Docker installation (on Windows and Mac at least), if not install it using the official instructions
Navigate to the hello-world-compose-web-app directory in the cloned repository
Build the Docker image with the name of your choice
Fill the missing part of the docker-compose.yaml file to make it use the container you just built
Start the containers with docker-compose up
Visit localhost:5000 in your web browser and hit refresh a couple times
Stop the containers by running CTRL+C in the previous terminal
Delete the containers with:
```
docker-compose rm
```
Start the containers again
1. What happened to the counter? Why?
2. Delete the containers again
Make the necessary changes in the Docker compose file so that when you delete and create the containers again the counter keeps its value

Hint: Use volumes, the redis container stores its data in the /data directory