Day 17 - Docker Project for DevOps

🔅 Dockerfile: -

Docker is a tool that makes it easy to run applications in containers. Containers are like small packages that hold everything an application needs to run. To create these containers, developers use something called a Dockerfile.

A Dockerfile is like a set of instructions for making a container. It tells Docker what base image to use, what commands to run, and what files to include. For example, if you were making a container for a website, the Dockerfile might tell Docker to use an official web server image, copy the files for your website into the container, and start the web server when the container starts.

Here are some of the most commonly used commands in a Dockerfile:

• FROM: Specifies the base image that the new image will be built on top of. For example, you might use an official Node.js image as the base for an application that runs on Node.js.

• RUN: Executes a command in the image. This command is run during the image build process. For example, you might use the RUN command to install necessary packages or dependencies for your application.

• COPY: Copies files from the host machine to the image. For example, you might use the COPY command to copy the files for your application into the image.

• ENV: Sets an environment variable in the image. For example, you might use the ENV command to set a variable that holds the version of your application.

• EXPOSE: Specifies the ports that should be exposed on the container. For example, you might use the EXPOSE command to specify that port 8000 should be exposed on the container.

• CMD: Specifies the command that should be run when a container is created from the image. For example, you might use the CMD command to specify that your application should be started when the container is created.

Example: -

• Best Practices for Writing Dockerfile

🔅 Run a DevOps Project using Docker: -

Step 1: - Create a Dockerfile for Nodejs application.

FROM node:12.2.0-alpine
WORKDIR app
COPY . .
RUN npm install
RUN npm run test
EXPOSE 8000
CMD ["node","app.js"]

1. here, we are using an official Node.js image (node:12.2.0-alpine) as the base for an application that runs on Node.js

2. WorkDir which is currently using is app

3. COPY is used to copy files from the host to the Image

4. The RUN command is used to install npm, which will install packages

5. Expose is used to expose port 8000, on which we are trying to run the application on the Web

6. CMD commands specify which commands to run while creating a container from the image.

---

Step 2: - Build the image

docker build . -t node-app

---

Step 3:- Run the container

docker run -d -p 8000:8000 node-app:latest

---

Step 4: - Check for port 8000 on the web for running the application

---

Step 5: - Log in to Docker Hub

---

Step 6: - Tag an Image that we want to push to Docker Hub

docker image tag node-app:latest pavanpawar57/node-app:latest

---

Step 7: - Once the Image is tagged then, need to push it into Docker Hub

docker push pavanpawar57/node-app:latest

So in this way, we can run a complete project using Docker.

Thanks for reading ❣️

Pavan Pawar