Dockerfile is a text file that contains instructions to automate the creation of a Docker image. It allows users to build images automatically by specifying commands in a Dockerfile. The build context refers to the files at the specified file path or URL used during the build process. A Dockerfile begins with a FROM instruction and can include instructions like LABEL, EXPOSE, WORKDIR, ADD, COPY, USER, ENV, RUN, ENTRYPOINT and CMD to customize the image.

1. Dockerfile

2. Agenda
● What is Dockerfile?
● Docker Build Context
● Dockerfile Format
● Dockerfile Instructions
● Demo

3. What is Dockerfile?
● It is simple Text file with a set of command or Instruction to perform the
actions on the base image to create a new docker image
● Docker can build images automatically by reading the instruction from
Dockerfile
● Using docker build users can create an automated build that execute several
command line instruction in succession

5. Docker Build Context
The Docker Build command build an image from Dockerfile and context
The Build context is the set of files at specified location Path or URL. The Path is a
directory on your local filesystem.
Maintain .dockerignore file same as .gitignore to exclude the context in build

6. Dockerfile Format
Dockerfile must begin with a FROM instruction
From may only be preceded by one or more ARG instruction, which declare
arguments that are used in FROM line in the file
Dockerfile format is
# Comment
INSTRUCTION arguments

7. Dockerfile Instruction: FROM

8. Dockerfile Instruction: LABEL

9. Dockerfile Instruction: EXPOSE

10. Dockerfile Instruction: WORKDIR

11. Dockerfile Instruction: ADD

12. Dockerfile Instruction: COPY

13. Dockerfile Instruction: USER

14. Dockerfile Instruction: ENV

15. Dockerfile Instruction: RUN

16. Dockerfile Instruction: ENTRYPOINT

17. Dockerfile Instruction CMD

18. Sample Dockerfile
# Step 1: Setup Node Container
FROM node:18 AS build
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm install
COPY . ./
RUN npm run build
# Step 2: Serve the application using Nginx
FROM nginx:alpine
COPY --from=build /app/build /usr/share/nginx/html
EXPOSE 80

19. Create Image using Dockerfile and Run the container
# cd $Project_folder
# docker build -t myreact-app .
[-t = Create tag on image]
[myreact-app = Tagname]
# docker run -td --name node -p 80:80 myreact-app:latest

20. Thank You