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 a DevOps/SRE/DevSecOps/Cloud Expert passionate about sharing knowledge and experiences. I have worked at Cotocus. I share tech blog at DevOps School, travel stories at Holiday Landmark, stock market tips at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow , and SEO strategies at Wizbrand.

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