Introduction to Docker

# Introduction to Docker

Matthias Jahn<br>
Peerigon GmbH<br>
[@matthaias](https://twitter.com/matthaias)

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# Agenda

1. What is Docker and why we need it
2. VM vs. Docker
3. Docker tools
4. Creating a container
6. Ecosystem
7. Alternatives
7. Demo

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### What is Docker?

.slides-columns.slides-content[
  .col[
    <img src="./assets/large_v-trans.png" width="300">
  ]
  .col[
    > Docker containers wrap a piece of software in a complete filesystem that contains everything needed to run: code, runtime, system tools, system libraries – anything that can be installed on a server. This guarantees that the software will always run the same, regardless of its environment.
  ]
]
.slides-quote-ref[https://www.docker.com/what-docker]

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### Images

* Read-only template for creating a container
* Example: A image contains an Ubuntu operating system and a node.js app
* Images can be downloaded or built from scratch
* An image can be based on another image
* Building an image is done via a `Dockerfile` or commiting a state of a running container
* An image consists of one ore more layers

<img src="./assets/layer.png" width="300">
.slides-quote-ref[https:docker.com]
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#### Containers

* A runnable instance of a Docker image
* A container can be sarted, stopped, moved or deleted
* While starting the container it is possible to add metadata like networking or env variables
* Each container is an isolated and secure app platform
* A container can get access to another container, persistent storage or databases

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### What is a container?

<img src="./assets/Docker-linux-interfaces.svg" width="400">
.slides-quote-ref[https://en.wikipedia.org/wiki/Docker_(software)]

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### Docker architecture

<img src="./assets/architecture.svg" width="600">
.slides-quote-ref[https://docs.docker.com/engine/understanding-docker/]

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### Why do we need something new?

.slides-columns.slides-content[
  .col[
  <div style="text-align: center; font-weight: bold">Complex application stack</div>
  * Static Page
  * Web Frontend
  * Workers
  * Database
  * Queue
  * Service X
  * ...
  ]
  .col[
  <div style="text-align: center; font-weight: bold">Platforms</div>
  * Developer machine
  * CI
  * Stage
  * Prod
  * Public Cloud
  * Private Cloud
  * ...
  ]
]

<!-----
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### Docker for

* fast, consistent delivery of applications
* responsive deployment and scaling
* running more workloads on the same server-->

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### Why should developers care?

* A portable runtime environment for the application
  * No missing dependencies
  * Instant developer environment
  * No constraints to languages or tools
  * Testing with different environments

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### Separation of concerns

.slides-columns.slides-content[
  .col[
  <div style="text-align: center; font-weight: bold">Developer</div>
  The developer cares about the inside of the container:
  * Code
  * Libs
  * Package manager
  * Apps
  * Data
  ]
  .col[
  <div style="text-align: center; font-weight: bold">Ops</div>
  The ops team cares about the outside of the container:
  * Logging
  * Remote access
  * Monitoring
  * Network

=> All apps start the same way
  ]
]

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### VM vs. Docker

.slides-columns.slides-content[
  .col[
  <div style="text-align: center; font-weight: bold">Similarities</div>
  * Isolation
  * Easy to move
  ]
  .col[
  <div style="text-align: center; font-weight: bold">Differences</div>
  * VM has own OS and Kernel
  * VM guest can be another OS than host
  * Docker offers copy-on-write
  * Docker starts with initial command
  * Container is "version controlled" (image layers)
  ]
]

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### VM vs. Docker

.slides-columns.slides-content[
  .col[
    <img src="./assets/WhatIsDocker_2_VMs_0-2_2.png" width="400">
  ]
  .col[
    <img src="./assets/WhatIsDocker_3_Containers_2_0.png" width="400">
  ]
]
.slides-quote-ref[https://www.docker.com/what-docker]

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### Docker tools

* Docker Engine
* Docker Compose
* Docker Registry
* Docker Machine
* Docker Swarm
* Kitematic

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### Docker Engine

<img src="./assets/engine-components-flow.png" width="500">
.slides-quote-ref[https://docs.docker.com/engine/understanding-docker/]

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### Docker Compose

.slides-columns.slides-content[
  .col[
* A tool for multi-container applications on a single host
* Reusing volume data 
* Recrating only changed containers
* Environment variables can be passed to a container
* Use cases:
  * Development
  * Testing
  * Single host deployments
  ]
  .col[
  <img src="./assets/Compose.png" width="300">
  .slides-quote-ref[https://github.com/docker/docker.github.io/blob/master/images/Compose.png]
  ]
]

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<div style="text-align: center; color: grey">docker-compose.yml</div>
```yml
 version: '2'
 services:
   db:
     image: mysql:5.7
     volumes:
       - "./.data/db:/var/lib/mysql"
     environment:
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: wordpress
       [...]
   wordpress:
     depends_on:
       - db
     image: wordpress:latest
     links:
       - db
     ports:
       - "8000:80"
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_PASSWORD: wordpress
```

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### Docker Registry

.slides-columns.slides-content[
  .col[
* Storage/Repo for Docker images
* Offers storage drivers like S3, Azure...
* Docker service: [hub.docker.com](https://hub.docker.com)
* Use Cases:
    * CI/CD Process
    * Distribute images easily in an own infrastructure
  ]
  .col[
  <img src="./assets/registry.png" width="150">
  .slides-quote-ref[https://github.com/docker/distribution]
  ]
]

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### Docker Machine

.slides-columns.slides-content[
  .col[
Docker machine creates Docker hosts and clusters on:
* Desktops 
* Cloud providers
* Own datacenter

]
  .col[
  <img src="./assets/MACHINE.png" width="150">
  .slides-quote-ref[https://www.docker.com]
  ]
]

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### Docker Swarm

.slides-columns.slides-content[
  .col[
* Included in the newest engine (used to be standalone)
* Native cluser for Docker engine
* Scaling, number of running instances of a task can be specified
* Multi-host overlay networking
* Service discovery
* Load balancing
* Rolling updates
  ]
  .col[
<div style="text-align: center; font-weight: bold">  
<img src="./assets/swarm.png" width="350">
.slides-quote-ref[https://www.docker.com]
</div>
  ]
]

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### Kitematic

.slides-columns.slides-content[
  .col[
* Graphical docker engine installer
* Docker Hub integration
* Allows to set and change:
  * Port mapping
  * Environment variables
  * Volumes
  ]
  .col[

<img src="./assets/Kitematic.png.png" width="500">

  ]
]
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### Building a image with a Dockerfile

<div style="text-align: center; color: grey">Dockerfile</div>
```Dockerfile
FROM node:6.5

WORKDIR /code/

COPY . .

RUN npm install --silent

CMD ["npm", "start"]
```

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### Ecosystem

.slides-columns.slides-content[
  .col[
#### Cloud services

* Docker cloud
* Amazon Web Sevices
* Google Cloud Platform
* Microsoft Azure
* ...
  ]
  .col[
#### Orchestration

* Swarm
* Kubernetes
* Nomad 
* Rancher
* DC/OS
* ...
  ]
  .col[
#### Operating Systems

* Linux with a 2.6.32+ kernel
* CoreOS
* Project Atomic
* RancherOS
* ... 
  ]
]

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### Alternatives

* Rkt
* LXC
* LXD

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### Demo

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# Thanks!