Demonstrate Docker Volume - Deploying a Todo app

Installing Docker:

Walk through the process of installing Docker on your machine. Provide step-by-step instructions for different operating systems. Here we are using ubuntu as a base machine.

Run the following command to uninstall all conflicting packages:

for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do sudo apt-get remove $pkg; done

Before you install Docker Engine for the first time on a new host machine, you need to set up the Docker repository. Afterward, you can install and update Docker from the repository.

Set up Docker's apt repository. Press Yes or Y in case of prompt.

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl gnupg
sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

# Add the repository to Apt sources:
echo \
  "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

To install the latest version, run:

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

If you're getting any errors i recommend you to visit here: Documentation

Now verify the installation execute the below command
```
    docker --version
```

Enable docker service

service docker start
service docker status

Adding Super user privileges
```
  sudo usermod -aG docker $USER
```
Setting up the GitHub project: Below is the project we will be using :
```
  https://github.com/theshubhamgour/django-todo-cicd.git
```

Clone the project

  git clone https://github.com/theshubhamgour/django-todo-cicd.git

You can see the docker file is already present

Let's build the file and execute the below command

docker build -t django-todo-app .

docker build: Initiates the build process to create a Docker image.
-t django-todo-app: Tags the resulting image with the name "django-todo-app." This is like giving a name to your image.
.: Specifies the build context, which is the path to the directory containing the Dockerfile and other necessary files for building the image. In this case, the . indicates that the Dockerfile is in the current directory.

Before running this command, make sure you are in the directory containing the Dockerfile for your Django todo app. The Dockerfile should define the necessary instructions for setting up the environment, installing dependencies, and copying your Django app into the image.

You can see now the image is successfully created run the below command

docker images

Let's execute this image which we have builded

docker run -d -p 8000:8000 django-todo-app:latest

docker run: This command is used to run a container based on a specified image.
-d: This flag runs the container in the background (detached mode), allowing you to continue using the terminal.
-p 8080:8080: This option maps port 8080 on your host machine to port 8080 in the container. This is assuming your Django application inside the container is set to run on port 8080. If your Django app uses a different port, you should adjust the mapping accordingly.
django-todo-app:latest: This specifies the image and tag to use for running the container. In this case, it uses the "django-todo-app" image with the "latest" tag.

Now Lets Go to AWS and do some configuration

Now to check whether the app is running fine go on the new tab and type

<public-ip>:8000/todos/ you will resemble the below screen

Add some data

Now let's restart the container and see what happens

docker restart <container-id>

Now let's stop and kill the docker container which is running

docker stop <container-id> && docker kill <container-id>

And now run the image again

docker run -d -p 8000:8000 django-todo-app:latest

Now refresh the page the data is gone - THIS CAN BE DANGEROUS

Let's create a storage point - a volume for our application which we will mount to our application

Here we created a directory name volumes under which we created another directory named django-app which will act as a storage point

/home/ubuntu/project/volumes/django-app

Now let's create the volume for our application which will help us to avoid the data loss

docker volume create --name django-todo-volume --opt type=none --opt device=/home/ubuntu/project/volumes/django-app --opt o=bind

docker volume create: This command creates a new Docker volume.
--name django-todo-volume: This specifies the name of the volume, in this case, "django-todo-volume."
--opt type=none --opt device=/home/ubuntu/project/volumes/django-app --opt o=bind: These options configure the volume. They specify that the volume type is "none" (indicating that Docker should not manage the volume), the device is the specified path on the host machine (/home/ubuntu/project/volumes/django-app), and the mount options are set to "bind."

This type of volume creation is known as a "bind mount," where a path on the host machine is mounted directly into the container. This is often used when you want to share files or data between the host and the container. In this case, it looks like you are creating a volume for a Django app located at /home/ubuntu/project/volumes/django-app.

Now Kill the running container

docker kill <container-id>

Now let's mount the volume we created to our docker image and target the working directory which is /data here

docker run -d -p 8000:8000 --mount source=django-todo-volume,target=/data django-todo-app:latest

docker run: This command is used to run a Docker container.
-d: This flag runs the container in the background (detached mode), allowing you to continue using the terminal.
-p 8000:8000: This option maps port 8000 on your host machine to port 8000 in the container. This is assuming your Django application inside the container is set to run on port 8000. Adjust the mapping accordingly if your Django app uses a different port.
--mount source=django-todo-volume,target=/data: This option mounts the volume named "django-todo-volume" into the container at the path "/data". This is a bind mount, where the host path (/home/ubuntu/project/volumes/django-app based on your earlier command) is mounted directly into the container at "/data".
django-todo-app:latest: This specifies the image and tag to use for running the container. In this case, it uses the "django-todo-app" image with the "latest" tag.

Now visit the volumes directory you will see the files

Now add the data in the todo app

Let's kill the container

docker kill <container-id>
docker rm <container-id>

Now let again run the docker file again and check whether the data is still present on gone

docker run -d -p 8000:8000 --mount source=django-todo-volume,target=/data django-todo-app:latest

BOOM we made it!!

Conclusion

In summary, creating a Docker volume for our Django application has proven to be a crucial step in preserving and securing application data. By implementing a named volume, "django-todo-volume," and utilizing bind mounts, we've established a robust mechanism to protect our data from removal or loss even when containers are updated or removed. Docker volumes not only enhance data integrity but also streamline the deployment and management of our containerized application. This practice ensures a persistent and reliable foundation for our Dockerized Django app, safeguarding its valuable data assets in the ever-changing landscape of container orchestration.