HarshPatel

Ahmedabad, Gujarat

Creating the Dockerfile

Inside our test application, create a new file called Dockerfile (capital D, no extension):

dockerfile

FROM node

ENV MONGO_DB_USERNAME=admin \
    MONGO_DB_PASSWORD=qwerty

RUN mkdir -p /home/app

COPY . /home/app

CMD ["node", "/home/app/server.js"]

Important Note About CMD Path

Since we are inside the test-app folder during development and can run:

bash

node server.js

directly, everything works locally.

But when the Docker container runs, we will be at the root filesystem level, where no server.js exists in the same location.

That is why we write the complete path:

text

/home/app/server.js

So Docker knows exactly where the file is inside the container.

Building a Docker Image From the Dockerfile

To build a Docker image from the Dockerfile, run:

bash

docker build -t test-app:1.0 .

Explanation

-t → tag (image name + version)
test-app:1.0 → image name and version
. → current directory (where Dockerfile exists)

Important Note

Run this command inside the test-app folder because that is where the Dockerfile is located.

After Build Completion

Verify the image:

bash

docker images

Now you will see:

test-app:1.0
mongo
mongo-express

Running the Container

bash

docker run test-app:1.0

Output

You will see:

text

Server running on port 5050

This means:

A container was created
The Node.js application is running inside the container
The app is successfully Dockerized

Running in Interactive Mode

bash

docker run -it test-app:1.0 /bin/bash

Inside the Container

Once inside, if we run:

bash

ls

We will see that:

The test-app folder and all files have been successfully copied into the container
The application code is available inside the Docker environment

Summary

Dockerfile defines how the image is built
docker build creates an image from the Dockerfile
docker run starts a container from the image
Application code is copied into /home/app inside the container
Node.js app runs using CMD
Everything runs in an isolated Docker environment

PreviousNext

Creating the Dockerfile

Inside our test application, create a new file called Dockerfile (capital D, no extension):

dockerfile

FROM node

ENV MONGO_DB_USERNAME=admin \
    MONGO_DB_PASSWORD=qwerty

RUN mkdir -p /home/app

COPY . /home/app

CMD ["node", "/home/app/server.js"]

Important Note About CMD Path

Since we are inside the test-app folder during development and can run:

bash

node server.js

directly, everything works locally.

But when the Docker container runs, we will be at the root filesystem level, where no server.js exists in the same location.

That is why we write the complete path:

text

/home/app/server.js

So Docker knows exactly where the file is inside the container.

Building a Docker Image From the Dockerfile

To build a Docker image from the Dockerfile, run:

bash

docker build -t test-app:1.0 .

Explanation

-t → tag (image name + version)
test-app:1.0 → image name and version
. → current directory (where Dockerfile exists)

Important Note

Run this command inside the test-app folder because that is where the Dockerfile is located.

After Build Completion

Verify the image:

bash

docker images

Now you will see:

test-app:1.0
mongo
mongo-express

Running the Container

bash

docker run test-app:1.0

Output

You will see:

text

Server running on port 5050

This means:

A container was created
The Node.js application is running inside the container
The app is successfully Dockerized

Running in Interactive Mode

bash

docker run -it test-app:1.0 /bin/bash

Inside the Container

Once inside, if we run:

bash

ls

We will see that:

The test-app folder and all files have been successfully copied into the container
The application code is available inside the Docker environment

Summary

Dockerfile defines how the image is built
docker build creates an image from the Dockerfile
docker run starts a container from the image
Application code is copied into /home/app inside the container
Node.js app runs using CMD
Everything runs in an isolated Docker environment

PreviousNext

Part 1: Complete Docker One Shot — End to End Guide

Part 1: Complete Docker One Shot — End to End Guide

Creating the Dockerfile

Creating the Dockerfile

Important Note About CMD Path

Building a Docker Image From the Dockerfile

Explanation

Important Note

After Build Completion

Running the Container

Output

Running in Interactive Mode

Inside the Container

Summary

Creating the Dockerfile

Creating the Dockerfile

Important Note About CMD Path

Building a Docker Image From the Dockerfile

Explanation

Important Note

After Build Completion

Running the Container

Output

Running in Interactive Mode

Inside the Container

Summary