Running a Ruby Application using Docker

Pre-requisite:- Docker

Docker is a containerization platform that allows you to package your applications and their dependencies into a lightweight and portable containers. Using Docker, you can easily deploy and run your applications on any platform that supports Docker, without having to worry about dependencies or environment differences.

One of the benefits of using Docker is that it allows you to isolate your applications and their dependencies from the host operating system. This makes it easier to manage your applications, as you don’t have to worry about conflicts with other software or libraries on the host.

To use Docker, you need to have the Docker Engine installed on your computer. You can then create Docker images for your applications, which are templates that contain the code and dependencies needed to run your application. You can then run these images as Docker containers, which are lightweight and standalone instances of your application that can be easily deployed and managed.

Docker is a powerful and popular tool for building, deploying, and managing applications. It is used by developers and organizations of all sizes, across a wide range of industries.

Steps to Run a Ruby App using Docker

Step 1: First, you will need to install Docker on your machine. You can download the Docker Engine from the Docker website and follow the installation instructions for your operating system.

Step 2: Create a Dockerfile. To create a Dockerfile for a Ruby application, you will need to specify the base image (e.g., Ruby) and any dependencies or libraries that your application requires. Here is an example Dockerfile for a Ruby application

1. FROM command is used to specify the base image that the Docker image will be built on top of. You can use any public or private image as the base image, or you can build your own image using a Dockerfile.
2. RUN command is used to execute shell commands within the context of the Docker image. The results of the command are stored in the image and will be available when the image is used to run a container.
3. The WORKDIR command is used to set the current working directory for subsequent commands in the Dockerfile. This allows you to specify the directory where commands should be run, without having to specify the full path for each command.
4. The COPY command is used to copy files from the host filesystem into the Docker image. You can use the COPY command to include any files or directories that your application needs in the image.
5. The bundle install command is used to install the Ruby gems specified in the Gemfile and Gemfile.lock files. The Gemfile lists the gem dependencies that your application needs, and the Gemfile.lock file lists the specific versions of the gems that will be installed.

Step 3: Build the Docker Image. Once you have created the Dockerfile, you can build the Docker image using the docker build command. This will create a Docker image based on the instructions in the Dockerfile. For example:

Step 4: Run the Docker Container. To run the Ruby application in a Docker container, you can use the docker run command. This will start a new container based on the Docker image you built in the previous step. For example:

This will start the Ruby application and expose it on port 3000. You can then access the application from a web browser or other client at http://localhost:3000.

You can use additional options with the docker run command to customize the environment and behavior of the container. For example, you can mount a volume to share files between the host and the container, or set environment variables to configure the application.

By following these steps, you can use Docker to run a Ruby application in a containerized environment. This can make it easier to develop, test, and deploy your application, as it allows you to package the application and its dependencies into a single container that can be easily run on any host.