Docker Intro

Deni Bertovic / @denibertovic

About me

Deni Bertovic

initeQ d.o.o.

denibertovic.com

About this talk

  • Docker 101
  • Images/Containers/etc
  • Development Environments
  • Automation
  • Deployment
  • Orchestration/Scheduling
  • Service Discovery
  • Questions at the end

    • What is Docker?

    What is Docker?

    • "Open platform for developers and sysadmins to build, ship, and run distributed applications. "
    • Light weight containers
    • Available on most linux distros

    What's a container?

    Traditional VM vs. Docker

    Images vs. Containers?

    Images vs. Containers

    Why should you care?

    • It's fast
    • Minimal overhead/resource usage
    • Run thousands of containers
    • Easy to run your whole production stack locally

    Architecture

    What we've learned so far?

    • Container - Light weight virtualization
    • Image - Immutable snapshot of a container
    • Hub/Index- Central hub for sharing images

    Docker CLI example

    user@host:/$ docker pull postgres
    user@host:/$ docker run -d -p 5432:5432 postgres

    Manipulating Containers

    user@host:/$ docker ps
    
CONTAINER ID  IMAGE      COMMAND   CREATED        STATUS
d03ba4afb47c  debian:7.5 /bin/bash 10 seconds ago Up 9 seconds

    user@host:/$ docker logs d03ba4afb47c
    user@host:/$ docker stop d03ba4afb47c
    user@host:/$ docker kill d03ba4afb47c
    user@host:/$ docker start d03ba4afb47c

    Images - Dockerfiles

    
FROM      debian:wheezy
ENV DEBIAN_FRONTEND noninteractive

...

RUN apt-get -qq update && apt-get -qq -y install postgresql-9.3 \
    postgresql-client-9.3 postgresql-contrib-9.3
ADD postgresql.conf /etc/postgresql/9.3/main/postgresql.conf
...

CMD /usr/local/bin/start_postgres.sh

    Dockerfiles

    user@host:/$ docker build -t username/postgres .

    Hub

    
user@host:/$ docker login
                        
    
user@host:/$ docker push username/postgresql
                        
    
co-worker@workstation2:/$ docker pull username/postgresql

    Recap

    • How to work with containers
    • Use Dockerfiles for building images

    How does docker fit into your dev environment?

    Requirements

  • Let's say we have to build a website for a conference called Webcamp Zagreb
  • We're going to use Python/Django
  • For starters we're going to need a database (PostgreSQL)
  • We want potential contributors to be able to bring up a dev env fast

    • Docker Compose

    https://docs.docker.com/compose/

    
# docker-compose.yml
db:
    image: postgres:9.3
    ports:
        - "5432:5432"

web:
    build: ./
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
        - ./:/code
    links:
        - db
    ports:
        - "8000:8000"

    Container links

    
root@web:/$ cat /etc/hosts

172.17.0.9  db
                    
    
                    root@f9e4e78c60c6:/# export
DATABASE_PORT="tcp://172.17.0.9:5432"
DATABASE_PORT_5432_TCP="tcp://172.17.0.9:5432"
DATABASE_PORT_5432_TCP_ADDR="172.17.0.9"
DATABASE_PORT_5432_TCP_PORT="5432"
DATABASE_PORT_5432_TCP_PROTO="tcp"

    Dockerfile

    
# Dockerfile
FROM python:2.7

ENV PYTHONUNBUFFERED 1

RUN mkdir /code
WORKDIR /code

ADD requirements /code/requirements
RUN pip install -r /code/requirements/dev.txt

    Benefits

    • Simplify runtime
    • Make sure everyone runs the same version of deps
    • What about virtualenv? --> C libraries!

    Everyone on the team runs the same version of database, cache, amqp, openssl, C libraries...etc

    Makes it easy to maintain a project that you haven't touched in a year!

    "docker-compose up" and do hotfix in 3 minutes, push to github, deploy

    Automation

    
IMAGE_NAME="denibertovic/myimage"

## Build image from Dockerfile.
build:
    docker build --rm -t $(IMAGE_NAME) .

## Push image to hub
push:
    docker push $(IMAGE_NAME)

## Run container with default command.
run: build_env
    @docker run -it \
        --log-driver=syslog \
        --env-file=/tmp/envfile \
        $(IMAGE_NAME)

## Spawn a bash prompt in a container.
bash: build_env
    @docker run -it \
        --log-driver=syslog \
        --env-file=/tmp/env \
        $(IMAGE_NAME) /bin/bash

    Hosting images

  • Docker Hub (has private repos)
  • Self hosted docker registry
  • DTR

    • Automate builds

  • Docker Hub has webhook support for github/bitbucket
  • Or just use Jenkins

    • Yeah but I have a Mac/Windows!

    Use Docker Toolbox!

    https://www.docker.com/toolbox

    Deployment

  • I'm talking about legacy stuff...
  • For single machine...Use Docker Compose
  • For multi node...
  • Use what you know!
  • Ansible/Chef/Puppet/Salt

    • Deployment

    
- name: redis container
  docker:
    name: myredis
    image: redis
    command: redis-server --appendonly yes
    state: started
    expose:
    - 6379

    Secrets

  • Hashicorp Vault
  • Shopify/ejson

    • Logging

  • Docker Logging Drivers:
  • Syslog
  • Journald
  • Fluentd
  • Gelf

    • Orchestration/Scheduling

  • Docker Swarm
  • Kubernetes
  • Mesos
  • Nomad

    • Service discovery

  • Consul
  • etcd
  • Zookeeper
  • Whatever/HA/key/value/store

    • In case it wasn't clear

    The last 6+ slides are ideas for future talks you should submit...

    Some more ideas...

    Docker Networking Plugins, Docker storage drivers...

    Thanks!

    Questions