I'm a DevOps

Overview

• Why do we need something else?
• What is Docker?
• Trying it out
• Tips and tricks

Dependencies

Software does not work in vacuum

Except you are in space

🛰

Your basic web app requires:

• Web server (Nginx, Apache)
• PHP
• SQL DBMS (PostgreSQL, MySQL)

A few steps forward add:

• NoSQL DBMS (ElasticSearch, Redis)
• Message broker (RabbitMQ)
• Cache
• WebSocket

You develop 2 projects.
They require:

• different configurations of the same dependency
• different versions of the same dependency

It steals your time!

Estimate the price of adding new PHP extension

Deployment and scaling

It would be good to have

• Ubiquitous dev, staging and prod environment
• Persistent environment configuration shipping
• Fast deploy
• Easy manage

Let's start our first app

What happened?

• PHP image downloaded
• Container created
• php -v executed
• Container stopped and removed

Virtualization

vs

Containerisation

Virtual Machine (VM)

• Emulates everything around.
• Starts from a system image.
• Supports different Guest OS on same host.
• Takes time to boot.
• Guest OS is not as efficient is Host

Virtualization

Same OS, same env, different apps

Virtual Environment (VE)

• No emulation – uses host kernel containerization.
• Fast start – only 50 ms
• Can use layered file systems (Overlay2, AuFS).
• Minimal performance impact.

Docker is an interface for containers management

Docker