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Why Docker?
Chris Tankersley
@dragonmantank
Dayton PHP, April 2017
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What Is Docker?
“Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications. Consisting of Docker Engine, a portable, lightweight runtime and packaging tool, and Docker Hub, a cloud service for sharing applications and automating workflows, Docker enables apps to be quickly assembled from components and eliminates the friction between development, QA, and production environments.”
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https://www.docker.com/whatisdocker/
Containers
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Normal Bare-Metal Server
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CPU RAM HD Network
Operating System
nginx PHP DB
Virtual Machines
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CPU RAM HD Network
Operating System
nginx PHP DB
Operating System
nginx PHP DB
Operating System
Hypervisor
Containers
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CPU RAM HD Network
Operating System
nginxnginx PHP DB PHP DB
Containers Are Not New
• LXC (Linux Containers)• OpenVZ• Systemd-nspawn• Qemu/kvm• BSD Jails• Solaris Zones• chroot
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Docker is an Ecosystem
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Docker Engine
Docker is an Ecosystem
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Docker ComposeDocker Machine Docker Swarm
How does it work?
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Uses a variety of existingContainer technologies
Server ContainersHyper-V Containers xhyve Virtualization
Sorry OSX < 10.10 and Windows < 10 Users
Docker Toolbox
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Using Docker – The Basics
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Running a container
• `docker run` will run a container• This will not restart an existing container, just create a new one• docker run [options] IMAGE [command] [arguments]• [options ]modify the docker process for this container• IMAGE is the image to use• [command] is the command to run inside the container• [arguments] are arguments for the command
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Running a simple shell
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Running a simple shell
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Running a simple shell
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What’s Going On?
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Ubuntu Kernel
/+ bin/+ etc/+ dev/+ home/+ usr/+ var/+ lib/+ …
/+ bin/+ etc/+ dev/+ home/+ usr/+ var/+ lib/+ …
php
nginx
bash
Running Multiple Copies of Software
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Running Two Webservers
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Some Notes
• All three containers are 100% self contained• Docker containers share common ancestors, but keep their own files• `docker run` parameters:• --rm – Destroy a container once it exits• -d – Run in the background (daemon mode)• -i – Run in interactive mode• --name – Give the container a name• -p [local port]:[container port] – Forward the local port to the container port
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As a Dev Environment
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Volumes
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Mounting from the host machine
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Mounting from the host machine
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Mounting from the host machine
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Mounting from the host machine
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Mounting from the host machine
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Mounting from the host isn’t perfect
• The container now has a window into your host machine• Permissions can get screwy if you are modifying in the container• Most things it creates will be root by default, and you probably aren’t root on
the host machine
• Host-mounted volumes are not portable at all• OSX and Hyper-V VMs have limited pathings to mount• OSX has poor I/O performance
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Simulating Networks
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Networking
• Docker can create multiple network “pools”• Each container gets an IP address• Containers can be attached to multiple networks• Docker network allow service discovery inside networks
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Legacy - Docker Links
• Legacy Links work with `--link`• Only works on the legacy “bridge” network• Doesn’t support service discovery
• Not worth it to use anymore
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Docker Networks
• Discreet IP pool for containers• Containers can be added and removed to the network at whim• Service discovery though ‘--network-alias’• Can be set up to work across hosts
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Create a network
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Attach to a network
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Ping the web container
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Add another web and kill web1
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Building Custom Environments
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Custom Images
• PHP images are pretty bare• Lots of times need to install extensions
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Dockerfile
• Dockerfile is the configuration steps for an image• Can be created from scratch, or based on another image• Allows you to add files, create default volumes, ports, etc• Can be used privately or pushed to Docker Hub
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docker/Dockerfile
FROM php:apache
RUN a2enmod rewrite
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Build it
docker build -t tag_name ./
• This runs through the Dockerfile and generates the image• We can now use the tag name to run the image
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Build it
docker build -t d4dapp docker/
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Use the new image
docker run -d --name d4dapp \
-v C:\drago\Projects\dockerfordevs-app:/var/www/ \
-p 8080:80
d4dapp
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Use the new image
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Containerizing Build Components
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Running Composer
docker run --rm \
-v c:/Users/drago/.composer:/root/.composer \
-v c:/Users/drago/Projects/workshop:/app \
-v c:/Users/drago/.ssh:/root/.ssh \
composer/composer \
install
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Run Multi-Tier Applications
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What is Docker Compose?
• Multi-container orchestration• A single config file holds all of your container info• Works with Docker Swarm and a few other tools, like Rancher
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Sample docker-compose.ymlversion: '2'
volumes: mysqldata: driver: local
services: d4dapp: build: ./docker/ volumes: - ./:/var/www/ ports: - 8080:80
mysqlserver: image: mysql environment: MYSQL_DATABASE: dockerfordevs MYSQL_ROOT_PASSWORD: 's3curep@assword' volumes: - mysqldata:/var/lib/mysql
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No longer use docker run
$ docker rm –f d4dapp
$ docker-compose up -d
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Now we have 2 containers
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Other Tools
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Docker Ecosystem
• Docker Machine• Docker Swarm
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Thank You!
• Software Engineer for InQuest• Author of “Docker for Developers”• https://leanpub.com/dockerfordevs
• Co-Host of “Jerks Talk Games”• http://jerkstalkgames
• http://ctankersley.com• chris@ctankersley.com• @dragonmantank
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