5. Docker in Production ✨

Table of Contents

• Docker in Production
  • Limit your Simultaneous Innovation
  • Legacy apps work in Containers too
  • Focus: Dockerfiles
  • Docker Maturity Model
    • Dockerfile Anti-Pattern: Trapping Data
    • Dockerfile Anti-Pattern: Using Latest
    • Dockerfile Anti-Pattern: Leaving Default Config
    • Dockerfile Anti-Pattern: Environment Specific
  • Big 3 Infrastructure Decisions

Table of contents generated with markdown-toc

Docker in Production

Limit your Simultaneous Innovation

• Many initial container project are too big in scope
• Solutions you maybe don't need on Day 1:
  • Fully automatic CI/CD
  • Dynamic performance scaling
  • Containerizing all or nothing
  • Starting with persistent data

Legacy apps work in Containers too

• Microservice conversion isn't required.
• 12 Factor is a horizon we're always chasing.
• Don't let these ideals delay containerization.

Focus: Dockerfiles

• More important than fancy orchestration; it's your new build and environment documentation.
• Study Dockerfile/ENTRYPOINT of Hub Officials

Docker Maturity Model

• Make it start
• Make it log all thing to stdout/stderr
• Make it documented in file
• Make it work for others
• Make it lean
• Make it scale

Dockerfile Anti-Pattern: Trapping Data

• Problem: Storing unique data in container

• Solution: Define VOLUME for each location

  VOLUME /var/lib/mysql
  
  ENTRYPOINT ["docker-entrypoint.sh"]
  
  CMD ["mysqld"]

Dockerfile Anti-Pattern: Using Latest

• Latest = Image builds will be o((⊙﹏⊙))o.

• Problem: Image builds pull FROM latest

• Solution: Using specific FROM tags

• Problem: Image builds install latest packages

• Solution: Specify version for critical apt/yum/apk packages.

  FROM php:7.0.24-fpm
  
  ENV NGINX_VERSION 1.12.1-1~jessie\
  	NODE_VERSION 6.11.4

  FROM ubuntu:xenial-20170915
  
  RUN apt-get update && apt-get install g++

Dockerfile Anti-Pattern: Leaving Default Config

• Problem: Not changing app defaults, or blindly copying VM conf.
  • E.g., php.ini, mysql.conf.d, java memory.
• Solution: Update default configs via ENV, RUN and ENTRYPOINT.

Dockerfile Anti-Pattern: Environment Specific

• Problem: Copy in environment config at image build

• Solution: Single Dockerfile with default ENV's, and overwrite per-environment with ENTRYPOINT script.

  FROM node:6.10
  
  COPY test-environment.json test-environment.json

Big 3 Infrastructure Decisions

• Containers-on-VM or Container-on-Bare-Metal ?
  • Do either, or both. Lots of pros/cons to either
  • Stick with what you know at first
  • Do some basic performance testing.
• OS Linux Distribution/Kernel Matters ?
  • Docker is very kernel and storage driver dependent
  • Innovations/fixes are still happening here.
  • "Minimum" version != "best" version
  • No pre-existing opinion ? Ubuntu 16.04 LTS
    • Popular, well-tested with Docker
    • 4.x Kernel and wide storage driver support
  • Or Infrakit and LinuxKit
• Container base Distribution: Which One ?
  • Which FROM image should you use ?
  • Don't make a decision based on image size (remember it's Single Instance Storage)
  • At first, match your existing deployment process
  • Consider changing to Alpine later, maybe much later.