Disclaimer:   Jamie isn't that good at Docker

Virtual Machine

Container

When to use Docker:

- If you already have a grasp on sysops

- For orchestrating multiple runtimes

- Orchestrating deploys on multiple servers

- Isolating multiple runtimes on a single server

- Separation of concerns on a systems level

- Replacing conventional VMs

- Establishing a consistent developer workflow

When NOT to use Docker:

- If you don't already have a grasp on sysops

- Single host, single runtime deployment

- Early optimization

- For nothing more than a consistent dev environment

- DOCKERIZE ALL THE THINGS

Before using Docker in Production:

- Secured least-privilege access (key based logins, firewalls, fail2ban, etc)

- Restorable secure off-site database backups

- Automated system setup (using Ansible, Puppet, etc)

- Automated deploys

- Automated provisioning

- Monitoring of all critical services

- Documentation, etc

debian image

Docker Layers

debian image

RUN apt-get install emacs

emacs

Docker Layers

debian image

RUN apt-get install emacs

RUN export ENV_VAR=value && mv ...

emacs

Docker Layers

some result

Debian

Docker Layers

apt-get install emacs

RUN export ENV_VAR=value && mv ...

emacs

some result

mutable app container

your app

Docker Layers

emacs

some result

writable container

your app

Docker Containers

debian

emacs

some result

mutable app

docker

host

nginx

redis

$ docker run -d -P training/webapp python app.py

Running A Container

Display Running Containers

$ docker-machine ip default

$ docker top agitated_brattain

Container Processes

$ docker stop agitated_brattain

Start, Stop, Destroy

Docker Images

Docker Images

Existing can be used to eliminate overhead. We can:

Use existing images

Create custom images

Orchestrate images

Custom Images

Dockerfiles are used to instruct how an image should be built

Concept: If all steps are followed an unlimited number of times, they should yield the same result

Images are the result of many layers of changes on top of some base environment (ie. Debian)

Custom Images

Example Dockerfile to build a simple node image

FROM node:latest

RUN mkdir /src

RUN npm install nodemon -g

WORKDIR /src
ADD . /src
RUN npm install

EXPOSE 3000

CMD npm start

Custom Images

Use Dockerfile to build a simple node image

Jamies-MacBook-Pro:docker-powerhour jcounsell$ docker build .
Sending build context to Docker daemon 4.167 MB
Step 1 : FROM node:6.2.1
6.2.1: Pulling from library/node
51f5c6a04d83: Downloading 16.78 MB/51.36 MB
a3ed95caeb02: Download complete 
7004cfc6e122: Download complete 
5f37c8a7cfbd: Downloading 22.59 MB/42.49 MB
8ad7684cace4: Waiting 
2cc6b7c79e1c: Waiting 
7d91187ae10f: Waiting 

... a ton of shit

Successfully built 8e06bdfbcc61

$

Docker Compose

Tool to orchestrate many docker images

web:
  build: ./app
  volumes:
    - "./app:/src/app"
  ports:
    - "80:3000"
  links:
   - redis
redis:
    image: redis:latest
    ports:
        - "6379:6379"

Docker Compose UI