...or how to start your adventure with Docker. Promises, goals and practical examples by one of our devs, Tomasz. Visit our blog for more! www.espeo.eu/blog

1. INTRODUCTION

2. INTRODUCTION
PROMISES
▸ isolation
▸ lightness
▸ repeatability
▸ speed
▸ easy collaboration
▸ easy configuration

3. INTRODUCTION
WHY DOCKER?

4. INTRODUCTION
TECHNOLOGIES
▸ LXC - Linux Containers - process
isolation
▸ UnionFS - layered file system
▸ Go - programming language
LINUX
UNION FS LXC
DOCKER (GO)

5. ▸ container - run
▸ image - build
▸ registry - pull/push
INTRODUCTION
TERMS AND OPERATIONS

6. EXAMPLE
MINECRAFT SERVER
# Minecraft 1.8.7 Dockerfile - Example with notes
# Use the offical Debian Docker image with a specified version tag, Wheezy, so
not all
# versions of Debian images are downloaded.
FROM debian:wheezy
# Use APT (Advanced Packaging Tool) built in the Linux distro to download Java, a
dependency to run Minecraft.
RUN apt-get -y update
RUN apt-get -y install openjdk-7-jre-headless wget
# Download Minecraft Server components
RUN wget -q https://s3.amazonaws.com/Minecraft.Download/versions/1.9.2/
minecraft_server.1.9.2.jar
# Sets working directory for the CMD instruction (also works for RUN, ENTRYPOINT
commands)
# Create mount point, and mark it as holding externally mounted volume
WORKDIR /data
VOLUME /data
# Expose the container's network port: 25565 during runtime.
EXPOSE 25565
#Automatically accept Minecraft EULA, and start Minecraft server
CMD echo eula=true > /data/eula.txt && java -jar /minecraft_server.1.9.2.jar

7. DEMO
JUMP AT THE DEEP END

8. DEMO
WHAT’S THE GOAL
▸ bpasik’s Node.js app with Mongo DB running on Docker
https://github.com/Gustu/Node-Asynchronous-Examples
TOOLS REFERENCE
▸ Docker hub
https://hub.docker.com/_/node
https://hub.docker.com/_/mongo/
▸ Dockerfile
https://docs.docker.com/engine/reference/builder/
▸ Docker compose
https://docs.docker.com/compose/

9. DEMO
BUILD IT
# Dockerfile
FROM node:onbuild
EXPOSE 3000
RUN IT
# run mongo as daemon container and expose it’s 27017 port to localhost’s 27017
# WARNING: on Windows or OS X Docker is not running on localhost
# it’s running on boot2docker VM with it’s own IP
# so it’s exposing this port as e.g. 192.169.99.100:27017
# (this also means you’d have to embed this IP into config/default.json)
$ docker run -d -p 27017:27017 mongo
<< mongo container id here>>
# build our app Docker image and tag it as node-app
$ docker build -t node-app .
<< lots of logs here >>
# run mongo as daemon and expose container’s port 3000 to localhost’s 3000
$ docker run -d -p 3000:3000 node-app
<< node-app container id here>>
# you can now access localhost:3000 and see the running containers
$ docker ps

10. DEMO
BUT RUNNING IT BY HAND EACH TIME IS UNCOOL…
# WARNING: remove all containers (running and stopped)
$ docker ps -qa | xargs docker rm -f
Cleanup
Declarative docker compose configuration
# docker-compose.yml
version: '2'
services:
web:
# use our Dockerfile
build: .
# expose the port 3000
ports:
- "3000:3000"
links:
# link the mongo container under hostname 'mongo'
# remember to change config/default.json to use mongo:27017
- mongo
mongo:
image: mongo
$ docker-compose up
# try changing public/index.html and refresh the page
Run it!

11. DEMO
WHAT IF WE WANT TO EDIT LIVE FILES?
$ docker-compose down
Cleanup (the docker-compose way)
Change our Dockerfile to use other base image
# Dockerfile
FROM node
EXPOSE 3000
# point to our volume (where the app is mounted)
WORKDIR /app
# start with the app’s start command
CMD [ "npm", "start" ]
$ docker-compose up
# try changing public/index.html again and see the changes live
Run it!
Change our docker-compose.yml to use a volume
version: '2'
services:
web:
build: .
ports:
- "3000:3000"
# mount . directory to container’s /app
volumes:
- .:/app
links:
- mongo
mongo:
image: mongo

12. DEMO
SUMMING UP
▸ we’ve started from running containers by hand
▸ defined Docker compose config with linked containers
▸ changed the app embedded in the image to be mounted
as a volume
▸ Dockerization available in my fork of the app:
https://github.com/tcichowicz/Node-Asynchronous-
Examples