Building Development Environments with Docker (Zendcon 2015)

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Building Development Environments with Docker Josh Butts Zendcon 2015

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About Me • VP of Engineering  at Offers.com • Austin PHP Organizer • github.com/jimbojsb • @jimbojsb 2

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About Offers.com • We help people save money • Launched in 2009 • 100k lines of PHP across several apps • Millions of Uniques / Month • Runs almost entirely in Docker 3

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Agenda In No Particular Order • What is Docker • Docker Terminology • Flow of Data in Docker • Running Docker • Docker CLI tools • Anatomy of a Dockerfile • Building a Dockerfile for PHP apps • Images & Containers • Docker orchestration • Docker Compose • Registries & Sharing Containers • Putting it all together

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DOCKER? What is 5

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BUILDING, RUNNING AND DISTRIBUTING APPLICATION CONTAINERS Docker is a tool for 6

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What is Docker? • Docker allows you to package applications with infrastructure • Docker uses Linux kernel container technology • Docker is well suited for distributed and highly available applications 7

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High Level Overview 8

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Who Cares? • Docker allows engineers to choose exactly the stack for any app • Containers run anywhere that runs Docker • Ops focuses on infrastructure instead of stacks 9

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Docker Dictionary - Container • Container • A running instance of your app and it’s complete software stack • You might have many identical containers running • Often runs just one process 10

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Docker Dictionary - Image • An image is the compiled distributable version of your app and it’s stack • Images are built from Dockerfiles • You can start many containers from the same image 11

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Docker Dictionary - Layer • Docker uses a layering system to optimize storage • Each line in your Dockerfile is a layer • Many layers make up an image • Images share common layers where possible 12

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Docker Dictionary - Dockerfile • The Dockerfile is a text file that lives in your project root • Describes how to build your image • Installs software packages, configures runtimes, etc • Tells Docker what command to run and what ports to open 13

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Docker Dictionary - Registry • A server that stores images • Provides organization and authentication as needed • Facilitates sharing of pre-built images • Example: DockerHub 14

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The Docker Binary • Both the CLI client and the server • Written in Go • Speaks REST-ish over Unix socket or TCP/SSL • CLI and server can be on different hosts 15

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Building Images 16 Dockerfile Image Container Registry Image Image Build Push/Pull Run

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How Containers Run • Docker daemon runs as root and starts containers • Containers are basically stateless • Can expose local storage if you need to • Can’t see each other’s files • State is gone on exit 17

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Outsource your Persistence • Cloud (AWS) example: • RDS for database storage • Sessions in Memcached or Redis • File storage in S3 • This may require changes to your app! 18

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Docker vs Virtualization • Docker is lightweight • No overhead of a guest OS • Docker can be controlled / contained by systemd and cgroups 19

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DOCKER What does it mean to run 20

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Running the Docker Daemon • Unless you’re running Linux, you need a VM (i.e. dev environment) • For MacOS / Windows, you want Vagrant for this • docker -d 21

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A Word on the Control OS • Any modern Linux should be able to run Docker • I personally don’t recommend Ubuntu • CoreOS is a small Linux distro that is designed to run Docker 22

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HELLO WORLD EXAMPLE Lets try a 23

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Naming Images • hello-world • hello-world:latest • _/hello-world • dockerhub.com/_/hello-world 24

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Naming Containers • Containers get a name • It’s different from the name of the image • It’s dumb by default • use --name 25

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Dockerfiles • FROM - specify your base image • RUN - run commands in the context • ADD - put your files in • EXPOSE - listen on ports • ENV - set environment vars • VOLUME - persistent storage 26

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DOCKERFILE Lets actually write a 27

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Typical Non-Linux Setup 28 MacOS Projects / Source Code Vagrant VM CoreOS Docker Daemon Containers Containers Containers Containers Docker CLI

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More on CoreOS • “Docker Native” • Auto Self-upgrading • Pay attention^^ • No package manager • Minimal wasted non-Docker resources 29

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Notes on Sample Docker VM • Based on CoreOS • Designed for development • Designed to be your only dev VM • Designed to run lots of containers simultaneously 30

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DOCKER VM Running a development 31

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Building Images from Dockerfiles • docker build . • use -t to give it a repo / tag • docker images to see what’s available on your system • docker rmi to delete images 32

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Running Containers • docker run --name [image] • At runtime you can • add volumes • specify port mappings • change the CMD 33

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PHP APPLICATIONS Building Dockerfiles for 34

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My Container Philosophy • ONE DOCKERFILE for your app • Use that docker file for dev and prod • Default to prod, configure for dev 35

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WORDPRESS Lets build a Dockerfile for 36

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Docker Compose • Docker Compose lets you orchestrate containers • Doesn’t do anything that Docker itself can’t do • YAML config file • Speaks the Docker Remote API 37

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Sharing Images • You probably want to run your own registry • SSL is required, you need a real TLD • This is a giant pain in the ass • Check out Quay.io 38

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CI Strategies • Auto build images from all pull request branches • Tag with :pr1234 • Use docker-compose to bring up test integration environment • Mysql with a ramdisk 39