Docker for developers
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The document presents a comprehensive overview of Docker, a platform that allows developers and sysadmins to build, ship, and run distributed applications using containers. It explains technical aspects, tools (like Docker Hub and Docker Compose), and provides examples on how to run and manage containers, including persistent data with volumes and networking between containers. Additionally, it discusses the use of Docker Machine for provisioning and Docker Swarm for cluster management, ending with insights on deployment and application structure with Docker Compose.
![Running a container
• `docker run` will run a container
• This will not restart an exisVng container, just create a new one
• docker run [opVons] IMAGE [command] [arguments]
• [opVons ]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
SunshinePHP 2016 16](https://image.slidesharecdn.com/dockerfordevelopers-160207173427/85/Docker-for-developers-16-320.jpg)
![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 interacVve mode
• --name – Give the container a name
• -p [local port]:[container port] – Forward the local port to the container port
SunshinePHP 2016 19](https://image.slidesharecdn.com/dockerfordevelopers-160207173427/85/Docker-for-developers-19-320.jpg)
![FROM phusion/baseimage:0.9.10
# …
CMD ["/sbin/my_init"]
# Nginx-PHP Installation
RUN apt-get update
RUN apt-get install -y vim git curl wget build-essential python-software-properties
php5-cli php5-fpm php5-mysql php5-pgsql php5-sqlite php5-curl
php5-gd php5-mcrypt php5-intl php5-imap php5-tidy mysql-client
# …
RUN mkdir /var/www
ADD build/default /etc/nginx/sites-available/default
# …
EXPOSE 80 22
VOLUME /var/www
VOLUME /etc/nginx
VOLUME /etc/php/
VOLUME /var/log
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
SunshinePHP 2016 36](https://image.slidesharecdn.com/dockerfordevelopers-160207173427/85/Docker-for-developers-36-320.jpg)
![Inspect a container
docker inspect [opVons] CONTAINER_NAME
• Returns a JSON string with data about the container
• Can also query
• docker inspect -f “{{ .NetworkSezngs.IPAddres }}” web_server
• Really handy for scripVng out things like reverse proxies
SunshinePHP 2016 39](https://image.slidesharecdn.com/dockerfordevelopers-160207173427/85/Docker-for-developers-39-320.jpg)
![Custom Docker File
FROM php:7-fpm
# Install modules
RUN apt-get update && apt-get install -y
libmcrypt-dev
&& docker-php-ext-install pdo
&& docker-php-ext-install pdo_mysql
CMD ["php-fpm"]
SunshinePHP 2016 69](https://image.slidesharecdn.com/dockerfordevelopers-160207173427/85/Docker-for-developers-69-320.jpg)
Docker for developers
- 2. Who Am I • PHP Programmer for over 11 years • Sysadmin/DevOps for around 9 years • Using Linux for more than 15 years • hGps://github.com/dragonmantank • Author of “Docker for Developers” • Reigning, Defending, Undisputed PHP MTG Champion of the World SunshinePHP 2016 2
- 5. What is it from a technical standpoint? • Docker is a wrapper around Containers • Docker Engine is the packaging porVon that builds and runs the containers • Docker Hub allows you to publish images for others to use • Docker Machine is a bare-metal provisioning tool • Docker Swarm is an load-balancing deployment tool • Docker Compose is a mulV-container build system SunshinePHP 2016 5
- 7. Normal Bare-Metal Server SunshinePHP 2016 7 CPU RAM HD Network OperaVng System nginx PHP DB
- 8. Virtual Machines SunshinePHP 2016 8 CPU RAM HD Network OperaVng System nginx PHP DB OperaVng System nginx PHP DB OperaVng System Hypervisor
- 9. Containers SunshinePHP 2016 9 CPU RAM HD Network OperaVng System nginx nginx PHP DB PHP DB
- 10. Docker can use many different containers • Since 0.9.0 it supports: • LXC (Linux Containers) – Started with LXC when it was released • OpenVZ • Systemd-nspawn • libvert-sandbox • Qemu/kvm • BSD Jails • Solaris Zones • chroot SunshinePHP 2016 10
- 11. Runs on *nix and Windows Hyper-V • No naVve container drivers for OSX • Amazon has ElasVc Container Service, and Microsoj Azure has Azure Container Service SunshinePHP 2016 11
- 12. Sorry OSX Users • Docker support is officially maintained through Docker Toolbox SunshinePHP 2016 12
- 13. Docker Toolbox also is for Windows SunshinePHP 2016 13
- 15. Assumptions • OSX and Windows users have Docker Toolbox installed • Linux users have the naVve binaries installed • The following images are downloaded: • php:7-fpm • php:7-cli • nginx • mysql • composer/composer SunshinePHP 2016 15
- 16. Running a container • `docker run` will run a container • This will not restart an exisVng container, just create a new one • docker run [opVons] IMAGE [command] [arguments] • [opVons ]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 SunshinePHP 2016 16
- 17. Running a simple shell SunshinePHP 2016 17
- 19. 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 interacVve mode • --name – Give the container a name • -p [local port]:[container port] – Forward the local port to the container port SunshinePHP 2016 19
- 21. Modifying a running container • `docker exec` can run a command inside of an exisVng container • Use Volumes to share data SunshinePHP 2016 21
- 22. Persistent Data with Volumes • You can designate a volume with -v • Volumes can be shared amongst containers • Volumes can mount data from the host system SunshinePHP 2016 22
- 23. Mounting from the host machine SunshinePHP 2016 23
- 24. 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 • Docker Toolbox’s VM only allows mounVng from within your home directory SunshinePHP 2016 24
- 25. Container Data Volumes • Uses a small container that does nothing but stores data • Have our app containers use the data volume to store data • Use ‘editor containers’ to go in and modify data when needed SunshinePHP 2016 25
- 27. Why not run SSH inside of the container? • Well, you can… • Docker is designed for one command per container • If you need to modify data, then you need to change your setup • If you have to run SSH, then you need a way to run SSH and your command SunshinePHP 2016 27
- 28. Why go through the hassle? • Data volumes are portable • Data volumes are safer • Separates the app containers from data • ProducVon can use a data volume, dev can use a host volume • Our app containers stay small SunshinePHP 2016 28
- 30. Docker Links • Allows containers to ‘see’ each other over the network • Each container thinks the other one is just another machine • Containers all have an internal network address, so we don’t need to expose everything through the host • Currently only works if all the containers are on one machine, Docker 1.10 should fix that SunshinePHP 2016 30
- 31. More Traditional Setup SunshinePHP 2016 31 INTARWEBS Nginx PHP-FPM Data Volume Port 9000 Editor
- 33. More Notes! • We can now rebuild secVons of the app as needed • We can restart nginx without impacVng PHP • We can extend much easier • Linked containers will not update if they are stopped/started • If we upgrade PHP, we have to destroy/create the web_server container again SunshinePHP 2016 33
- 34. Creating your own Images SunshinePHP 2016 34
- 35. Dockerfile • Dockerfile is the configuraVon 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 SunshinePHP 2016 35
- 37. 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 SunshinePHP 2016 37
- 39. Inspect a container docker inspect [opVons] CONTAINER_NAME • Returns a JSON string with data about the container • Can also query • docker inspect -f “{{ .NetworkSezngs.IPAddres }}” web_server • Really handy for scripVng out things like reverse proxies SunshinePHP 2016 39
- 40. Work with images • docker pull IMAGE – Pulls down an image before using • docker images – Lists all the images that are downloaded • docker rmi IMAGE – Deletes an image if it’s not being used SunshinePHP 2016 40
- 42. What is Docker Machine? • A provisioning tool that is used to set up a box with Docker • Used in Docker Toolbox to create the VM • Supports: • EC2 • Azure • Digital Ocean • Hyper-V • OpenStack • Virtualbox • VMWare SunshinePHP 2016 42
- 43. Creating a new machine SunshinePHP 2016 43
- 44. Why use it? • Makes it very easy to spin up new boxes • Docker Machine handles all of the dirty stuff for you • Docker Toolbox users are already using it • Integrates with Docker Swarm • It is not necessarily portable SunshinePHP 2016 44
- 46. What is Docker Swarm? • Cluster management tool developed by Docker • Looks like a machine running docker, but is actually many machines SunshinePHP 2016 46
- 47. Create a Swarm token $ docker run --rm swarm create 2 //... 340122bb69c98825b4ac7094c87a07e21 SunshinePHP 2016 47
- 48. Create a Swarm Master $ docker-machine create -d virtualbox --swarm --swarm-master --swarm-discovery token://40122bb69c98825b4ac7094c87a07e21 swarm-master SunshinePHP 2016 48
- 49. Add nodes to the swarm docker-machine create -d virtualbox --swarm --swarm-discovery token://40122bb69c98825b4ac7094c87a07e21 swarm-node-1 docker-machine create -d virtualbox --swarm --swarm-discovery token://40122bb69c98825b4ac7094c87a07e21 swarm-node-2 SunshinePHP 2016 49
- 50. Switch to the master eval $(docker-machine env --swarm swarm-master) SunshinePHP 2016 50
- 53. What is Docker Compose? • MulV-container orchestraVon • A single config file holds all of your container info • Works with Docker Swarm and a few other tools, like Rancher SunshinePHP 2016 53
- 55. Docker Compose in Action SunshinePHP 2016 55
- 56. Let’s build an application SunshinePHP 2016 56
- 57. The Goal • A three container applicaVon with nginx, php, and mysql • ApplicaVon will read and write to the database • Can deploy to a producVon machine SunshinePHP 2016 57
- 62. Bringing it to life SunshinePHP 2016 62
- 64. Docker Compose changes aren’t automatic • You will need to stop, then bring the system again • docker-compose stop • docker-compose up • Docker Compose will generally only restart boxes that have config changes • Docker Compose will not automaVcally fix links SunshinePHP 2016 64
- 65. Connecting to the database <?php $hostname = 'mysqlserver'; $database = 'dockerfordevs'; $user = 'root'; $password = 'docker'; $dbh = new PDO('mysql:host=' . $hostname . ';dbname=' . $database . '', $user, $password); echo 'Hello World'; SunshinePHP 2016 65
- 67. Why didn’t it work? • Default PHP images ship with barely any extensions enabled by default • We will need a custom PHP Image SunshinePHP 2016 67
- 70. Let’s try that again SunshinePHP 2016 70
- 72. I can’t answer this for you SunshinePHP 2016 72
- 74. Each situation is different • You will probably build something custom, using exisVng tools • Do you use data volumes? • Do you just package the enVre compiled app? • Does it need to be distributed? • Is it going on Swarm, or Amazon ECS? SunshinePHP 2016 74
- 75. Things to consider • Docker Compose will only deploy an app to one server • Docker Swarm is preGy low-level and bare-bones • Volumes on Swarm cannot be shared across hosts • Host mounVng is 99.99999% of the Vme not what you want to do SunshinePHP 2016 75
- 76. Rancher is a good start • Provides a nice GUI to manage everything • Allows volume sharing and networking across hosts • Works with docker-compose.yml files • These files can be supplemented with environment variables SunshinePHP 2016 76