Day 17 Task: Docker Project for DevOps Engineers.

DockerFile:-

Docker can build images automatically by reading the instructions from a Dockerfile. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. This page describes the commands you can use in a Dockerfile.

Format

Here is the format of the Dockerfile

# Comment
INSTRUCTION arguments

The instruction is not case-sensitive. However, the convention is for them to be UPPERCASE to distinguish them from arguments more easily.

Docker runs instructions in a Dockerfile in order. A Dockerfile must begin with a FROM instruction. This may be after parser directives, comments, and globally scoped ARGs. The FROM instruction specifies the Parent Image from which you are building. FROM may only be preceded by one or more ARG instructions, which declare arguments that are used in FROM lines in the Dockerfile.

Docker treats lines that begin with # as a comment unless the line is a valid parser directive. A # marker anywhere else in a line is treated as an argument. This allows statements like:

# Comment
RUN echo 'we are running some # of cool things'

Dockerfile instruction

• FROM > Base Image

• ADD/COPY > Add files and folder into the image

• RUN > Execute commands in a new layer and commit the results.

• EXPOSE> Containers listen on the specified network ports at runtime.

• CMD > Run binaries /commands on docker run

Task:-

• Create a Dockerfile for a simple web application ( Python app)

• Build the image using the Dockerfile and run the container

• Verify that the application is working as expected by accessing it in a web browser

• Push the image to a public or private repository (e.g. Docker Hub )

Follow the Steps:-

1. Clone the GitHub repository from where you will get your required files.

   

   

2. remove the previous Dockerfile.

   

3. vim DockerFile add the below content in it

   1.   vim Dockerfile
      
         # Dockerfile content
         FROM python:3.9
         COPY . .
         RUN pip install -r requirements.txt 
         EXPOSE 8001
         CMD ["python","manage.py","runserver","0.0.0.0:8001"]
      

      To Build the image from Dockerfile.

      

      Run the image to create the container.

1. Verify application is working in a web browser.

   

   Push the image to a public or private repository. (eg. dockerhub)

   create a docker hub account

   create a docker hub public repository

   change local image tag according to the docker hub suggest

   

Push the image to a public or private repository docker push.

docker push username/docker latest image

note:-In tag command provides the name of the latest image.

Check we can successfully push the docker image on Docker Hub.