Dockerfile best practices

The aim of the repository is to understand some of the best practices for writing a Dockerfile for a java maven project hands on as discussed in dockerfile-best-practices

A better Dockerfile is written as you go from master branch to 1-order-matters-for-caching till you reach 11-multi-stage-builds-to-remove-build-deps

The idea of using git branches for presenting the outcome of each applied best practice is taken from Github-dockerfile-best-practices-nodejs

The master branch also has a python flask rest app to practice writing Dockerfile for a python project

Following Dockerfile best practices will help in five areas:

1. Incremental build time

2. Image size

3. Maintainability

4. Security (pending)

5. Repeatability

Improving incremental build time:

1. Order matters for caching

2. More specific COPY to limit cache busts

Reduce Image size:

 1. Remove unnecessary dependencies
 
 2. Remove package manager cache

Maintainability:

1. Use official images when possible

2. Use more specific tags

3. Look for more minimal flavors

Reproducibility:

1. Line buddies: apt-get update & install in singe RUN statement?

2. Build-from-source in a consistent environment

3. Fetch dependencies in a spearate step

4. Use multi-stage builds to remove build dependencies

Running the java project in docker container

   Install docker and run the docker daemon

   $ sudo dockerd &    


   Clone the repository 

   $ git clone https://github.com/aditya-suripeddi/dockerfile-best-practices.git


   Go to the project directory 

   $ cd dockerfile-best-practices


   Build the container image

   $ docker build -t java-app . 


   Run the container

   $ docker run java-app

Links to best practices

Improving Incremental build time

1-order-matters-for-caching

2-more-specific-copy-to-limit-cache-busts

Reproducibility?

3-line-buddies-apt-update-install

Reduce Image Size

4-remove-unnecessary-dependencies

5-remove-package-manager-cache

Maintainability

6-use-official-images

7-use-more-specific-tags

8-look-for-minimal-flavors

Reproducibility

9-build-from-source-in-consistent-environemnt

Improving Incremental build time?

10-fetch-dependencies-in-a-separate-step

Reduce Image Size? multi-stage-builds-reduce-image-size

11-multi-stage-builds-to-remove-build-deps

References:

1. Intro-guide-to-dockerfile-best-practices

2. Reference-slides-of-the-blog-above

3. Github-dockerfile-best-practices-nodejs: the presentation format with different github branches is taken from this repository

4. Dockerfile-best-practices

5. Dockerdocs-dockerfile-best-practices

6. Hexops-dockerfile-best-practices