Basic Dockerfile

Create an Image with Docker Build

Each docker container is based on an image. This image is built using a dockerfile that exists at the root of the project directory. Example for a node.js app:

# Use nodejs as a base image
FROM node:14
 
# Describe the directory inside the container
WORKDIR /app
 
# Copy the package json file inside the dir
COPY package.json .
 
# Install dependencies
RUN npm install
 
# Copy the rest of the code
COPY . .
 
# Expose the app
EXPOSE 3000
 
# Run the node command
CMD ["node", "app.js"]

Build the Image and Tag it

The image can then be built with the following command. This is mandatory to push it to platforms like Dockerhub

• -t flag to give the image a name and an optional tag

sudo docker build -t <image-name>:<image-tag> .

Build the Image with a Custom Dockerfile

In order to build an image with a non-standard Dockerfile, run the following command:

• -f flag to provide the name of the docker file that’s used for building

sudo docker build -f Dockerfile.prod -t <image-name>:<image-tag> .