Download pdf - Why Docker? Dayton PHP, April 2017

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


Using Docker – The Basics


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


Running a simple shell






What’s Going On?


Ubuntu Kernel

/+ bin/+ etc/+ dev/+ home/+ usr/+ var/+ lib/+ …

/+ bin/+ etc/+ dev/+ home/+ usr/+ var/+ lib/+ …

php

nginx

bash

Running Multiple Copies of Software


Running Two Webservers
















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


As a Dev Environment


Volumes


Mounting from the host machine










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


Simulating Networks


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


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


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


Create a network


Attach to a network


Ping the web container


Add another web and kill web1


Building Custom Environments


Custom Images

• PHP images are pretty bare• Lots of times need to install extensions


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


docker/Dockerfile

FROM php:apache

RUN a2enmod rewrite


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


Build it

docker build -t d4dapp docker/



Use the new image

docker run -d --name d4dapp \

-v C:\drago\Projects\dockerfordevs-app:/var/www/ \

-p 8080:80

d4dapp


Use the new image


Containerizing Build Components


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


Run Multi-Tier Applications


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


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


No longer use docker run

$ docker rm –f d4dapp

$ docker-compose up -d


Now we have 2 containers


Other Tools


Docker Ecosystem

• Docker Machine• Docker Swarm


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• [email protected]• @dragonmantank


https://leanpub.com/dockerfordevs

https://leanpub.com/dockerfordevs

http://ctankersley.com/

mailto:[email protected]