I'm a Docker Rocker and So Can You!

Introducing the basics of Docker, what it is, and how to adopt to the Docker paradigm and the "docker way".

Transcript

1. I’m a Docker Rocker and So Can You I Can Hardly Containerize My Excitement Hosted by Buster “Silver Eagle” Neece
2. What is Docker?
3. What Wikipedia Says Docker is • Initially released in 2013 • Builds on top of existing Linux technologies like LXC, cgroups, etc • Used to run software packages called "containers"
4. Containers • Standalone software packages configured by “images” • Isolated from each other and use their own set of tools and libraries • Communicate with each other through well-defined channels (mostly TCP/IP) • Share the same kernel • More lightweight than virtual machines
5. What This Means for You • Better dev and production parity: You can use the same Docker image(s) to power both your local dev environment and your production servers! • Easier spin-up of new machines/servers/team members: Images are all configured in predictable text files Pre-built images can be uploaded to a “hub” and pulled down quickly • Go “web-scale” in a jiffy: If you build your app right, you can go from one container doing one thing to a hundred doing that thing
6. Thinking Like Docker
7. Where we are (or were): Vagrant and Virtual Machines Pros: • Everything’s in one big honkin’ VM • You can SSH into the VM and goof around to your heart’s content • Can use existing infrastructure automation tools (like Ansible, Chef, or Puppet) Cons: • Everything’s in one big honkin’ VM • Changes you’ve made inside the VM after the provision aren’t saved or documented anywhere • Small and subtle differences between local dev and production servers add up to pain points down the road
8. Splitting the App Up PHP Web Application (php-fpm) Web Server Database Cache Virtual Machine PHP Web Application Database Web Server Cache
9. The Docker Way • Each container has one single command that it runs • When the command exits, the container stops • Daemons aren’t a thing; some containers just have really long-running commands and don’t exit • Commands can be anything you’d run in a shell • If you absolutely need to run more than one thing in a Docker container, you can use tools like Supervisor: http://supervisord.org/ Each container should only do one thing
10. The Docker Hub (hub.docker.com) Prebuilt Images for: • Nginx • Apache • PHP • MySQL/MariaDB • MongoDB • and much more For PHP Developers: • Wordpress • Drupal • Magento • MediaWiki • etc
11. Roll Your Own Images • Defined by a Dockerfile • FROM scratch ◦ FROM debian:stretch-slim ▪ FROM php:7.2-stretch ◦ FROM ubuntu:bionic ▪ FROM ◦ FROM alpine:latest ▪ FROM php:7.2-alpine
12. Docker Image Layering
13. Example Dockerfile FROM ubuntu:bionic MAINTAINER Foo Barrington version: 0.1 RUN apt-get update && apt-get install -y apache2 && apt-get clean && rm -rf /var/lib/apt/lists/* ENV APACHE_RUN_USER www-data EXPOSE 80 CMD ["/usr/sbin/apache2", "-D", "FOREGROUND"] https://docs.docker.com/engine/reference/builder/
14. Does Size Matter? Try Alpine • Alpine Linux • Built for containers • Base image size of ~3MB • Uses musl instead of glibc • Lots of prebuilt images: ◦ nginx:alpine ◦ php:7.2-alpine ◦ redis:alpine
15. Remember, Containers Go Away.
16. Where to Store Stuff • Temporary files may not need to be stored outside the container! • Flat files: Share a volume between containers (volumes don’t go away) • Databases: Store sessions and other persistent data in your DB • Dedicated Cache: Store caches and sessions in a dedicated key/value store, like Redis or Memcached ^ Handy library for abstracting caching: Stash http://www.stashphp.com/
17. Environment Variables Are Your Friend • Can be passed into Docker containers easily: ◦ From the docker run command ◦ Inside docker-compose.yml ◦ If using Docker Compose, they can also be in .env at the project root • Can easily customize for each environment you’re running in • Helpful tool for importing env files if you’re not in Docker: DotEnv https://github.com/symfony/dotenv Caveat: By default, PHP-FPM doesn’t pull environment variables from where it’s running, instead has them sent over by the web server (nginx, Apache, etc) You can add: clear_env = no ...to php-fpm.conf to change this behavior
18. Tools That Help
19. Docker for Linux • Native support on many distros (CentOS, Ubuntu, Debian, etc) • Nowadays split into Enterprise Edition ($$$) and Community Edition (free!) • Packages often named docker-ce • May need to install a PPA for latest version • Very high performance and low overhead
20. Docker for Windows and MacOS Docker for Windows • Uses HyperV • Requires Windows 10 Pro • Kubernetes support out of the box • Some known issues Docker for MacOS • Uses’s MacOS’s Hypervisor API / xhyve Docker Toolkit • Considered “legacy” version • Uses VirtualBox • Includes docker-compose
21. docker-compose • Python utility script, originally called “Fig” • One single file, docker-compose.yml, that defines how multiple services interact, exposed ports, volumes, networks, etc. • Turns what could be a 40-line Docker bash command into: docker-compose up -d • Comes with Docker for Windows and Mac, can be installed by itself too: https://docs.docker.com/compose/install/#install-compose
22. Example docker-compose.yml version: '3.3' services: db: image: mysql:5.7 volumes: - db_data:/var/lib/mysql restart: always environment: MYSQL_ROOT_PASSWORD: somewordpress MYSQL_DATABASE: wordpress MYSQL_USER: wordpress MYSQL_PASSWORD: wordpress wordpress: depends_on: - db image: wordpress:latest ports: - "8000:80" restart: always environment: WORDPRESS_DB_HOST: db:3306 WORDPRESS_DB_USER: wordpress WORDPRESS_DB_PASSWORD: wordpress volumes: db_data:
23. docker-app • Brand new, experimental program • Extends upon Docker Compose to create a .dockerapp file that contains: ◦ Project metadata ◦ Docker-compose-style services ◦ Environment-specific settings • Docker App can be distributed on the Docker Hub just like a Docker image • Works directly with Kubernetes and can generate Helm charts for you • Check it out at https://github.com/docker/app
24. Kitematic • https://kitematic.com/ • Powerful GUI for Windows/Mac • Explore images • View all running containers
25. Thanks! Buster “Silver Eagle” Neece @SlvrEagle23 azuracast.com