DevOps - The Introduction Course: 1

Introduction to Chef

Configuration push is initiated with the master node (from 'cook' to 'servers'), e.g. Ansible, Saltstack
pull - you can think of it as a 'buffet', where the customer periodically walks up to the table and takes what they need, e.g. Puppet, Chef

Generic concepts used by operating systems and other orchestration tools

An idempotent task is one that yields the same result when repeated multiple times
- e.g. asking a waiter to fill your glass of water: whether it's empty, half-full or already full (requiring no action), you'll always end up with a full glass of water
- e.g. in user creation, if the user doesn't exist then the user is created; if they do, then the operation is skipped:
```
    user 'sam' do
      action :create
    end
```
Convergence means "to bring together"
- e.g bringing together a set of ingredients to cook a dish. The dish requires noodles - if they're already cooked, skip them; otherwise, cook noodles. While adding salt, taste to see if there's enough already before adding more.
- What's important is that at the end of the process we get the same dish we're expecting that tastes the same, with the right amount of ingredients.
Summary
- No complex scriptting
- Consistent in heterogenous environment
- Imperative and declarative patterns
- Idempotent

SSH'd into an Ubuntu VM
Revised YAML
Learned about automation in Chef
- Imperative vs Declaritve programming: is declarative == abstraction? Apparently, yes!
Read a chapter of 'The Phoenix Project')