Docker Tutorials: Image – Create a image using Dockerfile

We learnt docker so we can create better docker images using dockerfile?

What is dockerfile?

- a file
- contains instructions
- for writing each layer
- multiple layers == one image

Rule of dockerfile?

• each line ==== one layer
• Each layer would be created from a container from the previous layer

Example of Dockerfile

FROM ubuntu
MAINTAINER Rajesh Kumar <rajesh@devopsschool.com?
RUN apt-get update
RUN apt-get install git -y
COPY index.html /optCode language: JavaScript (javascript)

FROM ubuntu
MAINTAINER Rajesh Kumar <rajesh@devopsschool.com?
RUN apt-get update
RUN apt-get install git -y
COPY index.html /optCode language: JavaScript (javascript)

FROM httpd
MAINTAINER Rajesh Kumar <rajesh@devopsschool.com?
RUN apt-get update
RUN apt-get install git -y
COPY index.html /optCode language: JavaScript (javascript)

   15  mkdir dock-image
   16  cd dock-image/
   17  clear
   18  vi dockerfile
   19  touch index.html
   20  docker build -t ub-up-git .
   21  docker images

Lab & Excercise

- https://devopsschool.com/tutorial/docker/dockerfile/dockerfile-example-sample-lab.html

Example of App Dockerfile
# https://github.com/jenkinsci/docker/blob/587b2856cd225bb152c4abeeaaa24934c75aa460/Dockerfile
# https://github.com/tianon/docker-brew-ubuntu-core/blob/50b110c15148c069706b155a60d21ecfcbb59de9/focal/Dockerfile
# https://github.com/docker-library/httpd/blob/6d68525ac47c0474d3d74269b2669104c1d867dd/2.4/Dockerfile

How to set PID1 for the image?
- CMD or ENTRYPOINT

Reference 
- https://devopsschool.com/tutorial/docker/commands/index.html
- $ docker help
Code language: PHP (php)

Reference

• https://www.devopsschool.com/blog/example-and-sample-programs-of-dockerfile/
• https://www.devopsschool.com/blog/understanding-dockerfiles-instructions-options-of-docker/
• https://www.devopsschool.com/blog/dockerfile-lab-exercise-1/
• https://www.devopsschool.com/blog/how-to-create-a-image-using-dockerfile/

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.