Intro to AWS

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# Intro to Amazon Web Services

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### A Brief History of Amazon Web Services

AWS was born out of a startup struggling to stay on top of massive demand.
* In the early 2000s, Amazon was building infrastructure and tools to support Amazon.com.
* In 2006, Amazon brought their tools and infrastructure public with EC2.
* They were the first company to make a public cloud offering..
* Currently AWS control 35% of the cloud market
* AWS offers 98 different products

[70% of Internet Traffic Goes Through AWS Northern Virginia](http://www.nextgov.com/analytics-data/2016/01/70-percent-global-internet-traffic-goes-through-northern-virginia/124976/)
...

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## AWS Acronyms

**EC2** These are virtualized Linux, Windows, and Mac comupters that you rent from Amazon.
* Amazon gives you an IP address and SSH access to the computer.

**S3**  Cloud storage. Imagine a virtual, cloud file system. 
* Amazon gives you a access to a RESTful API that is used to store pretty much anything you want.

**RDS** Database.  High availability databases in any flavor you like (MySQL, Postgres, Oracle, MariaDB).
* Amazon gives you either an internally facing or externally facing IP address to connect to.

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## Why AWS?

You have options:
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* AWS
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* Google Cloud
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* Microsoft Azure
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* DigitalOcean
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* Linode ... hundreds more
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### People choose because it is the **complete tool** for **highly available** systems.

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## AWS High Availability

AWS has an uptime of **99.95%**.

### **99.95%** uptime is about **4 hours** of downtime a year.

*4 hours of downtime is not good enough for most companies*

###**Redundancy**

Reducing the the points of failure by creating failover back up systems.

* You can achieve even higher uptime by distributing your systems across  "Availability Zones".

* Amazon has 52 Availability Zones across the globe.  Each "AZ" is independently powered and cooled.  Each has their own networking and security.

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## AWS: **Complete** Toolset

AWS gives you everything that you would normally have in a data center and more:

* Easy to configure system access and security (**IAM**)

* Fine grained network security (**VPC**)

* Auto scaling servers (**Elastic Beanstalk**)

* Remote permanent storage (**S3**)

### AWS makes it "easy" to build out a resilient cloud application.
*(it's a lot of work to build out these tools on your own)*

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## **AWS** by Example

* How does AWS make things easy for the developer?

* How does AWS help your systems scale?

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## **AWS** by Example

Single Server Application
<img src="images/simple_single_server.png"></img>

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## **AWS** by Example

EC2 Server Simply Overwhelmed
<img src="images/simple_server_simply_overwhelmed.png"></img>

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## **AWS** by Example

### Single Server Situation

As traffic increases, having one server causes problems:

* Eventually the server reaches peak utilization and has to be upgraded.
* Since the one server is running both the web application and the database (and perhaps more) a performance problem on one system brings down everything.
* The single server is a point of failure.  If that server goes down, the applciation and all of the data goes with it!

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## **AWS** by Example

### The **Solution**

**RDS** Database

* An **RDS** database is simply an specialized EC2 instance that has Postgres, MySQL, Oracle, or MariaDB installed.

* An **RDS** databases have a few extra perks.

* An **RDS** database has **high availability**.  This means that behind the scenes AWS automatically creates multiple copies of your database in different datacenters.  If one data center goes down, your database is still up.

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## **AWS** by Example

Server with a separte Database

**Warning!** The communication between the web application and the database is not encrypted!

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## **AWS** by Example

### Cloud Security

* Traditional data centers protect data with with physical security and firewalls.

* In the cloud, **EVERYTHING** is potentially open to the public.

###Solution

* VPN networks can encrypt data moving across a group of computers.

*OR*

* AWS offers a **VPC** Virtual Private Cloud that acts as a data center around your cloud infrastructure.

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## **AWS** by Example

### Virtual Private Clouds

* **VPC**s are logically separated from all other virtual networks on AWS.

* **VPC**s create a virtual network on the cloud that is invisible to the rest of the internet.

* Since the network is invisibile to the outside world, the data is generally* safe to travel unencryped between devices.

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## **AWS** by Example

EC2 Server with a database in a VPC
<img src="images/simple_server_with_database_vpc.png"></img>

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## **AWS** by Example

As the app traffic increases, the load on the server increases.

The increased load has also causes sysytem failures resulting in downtime.

### Solution

Elastic Load Balancers
* ELBs distribute traffic across multiple servers.

* ELBs are smart.  They continuously check on their servers.  If a server goes down, it reroutes traffic to other servers in the group.

* ELBs are also **High Availability**.  Essentially, they will almost never go down.

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## **AWS** by Example

**EC2** Server behind an **ELB** using an **RDS** database within a **VPC**

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## **AWS** by Example

Keep scaling as many **EC2** instances as you need!

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## The Key is the **VPC**

**VPC** stands for Virtual Private Cloud.

The **VPC** is a virtually isolated network i.e. "bubble" on the internet.

* By default, nothing can enter or your leave your **VPC**. There is zero access to or from the internet.

* Access to end from the **VPC** is configured through fine grained network **Access Control List**.

* Inside the **VPC*, subnets can be configured with additional ACLs for even more fine grained control.*

* The VPC is initialized by providing a **CIDR** block to define the IP space.

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** Another VPC Diagram **
<img src="images/AWS-VPC-Diagram.png"></img>

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## A word about **CIDR** Blocks

CIDR is a notation used to describe the IP addresses within a network or subnet.

<br>
CIDR addresses are composed of two parts:
1. A template for the IP address `192.168.0.0`
2. A bit mask indicating the range of IP addresses available.  `/24`

Put them together and you have a full CIDR block!  `192.168.0.0/24`.

* The **CIDR** bit mask controls how many IP addresses are allocated to a network or subnet.

* The **CIDR** template indicates what range of IP addresses you want to use.

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## CIDR examples

### **Primer** - IPv4 address space spans from `0.0.0.0` to `255.255.255.255`
* A total of 4,294,967,296 possible IP addresses.

```
192.168.0.0/24     .............  192.168.0.0 - 192.168.0.255
192.168.0.0/16     .............  192.168.0.0 - 192.168.255.255
0.0.0.0/8          .............  0.0.0.0 - 0.255.255.255
0.0.0.0/0          .............  0.0.0.0 - 255.255.255.255
```

Most of the time ... pick your favoriate IP address range and choose a bit mask of 
* **24** - 255 Possible IP addresses - small network or subnet 
* **16** - 65,536 Possible IP addresses - large network or subnet
* **0** -  44,294,967,296 Possible IP addresses - VERY large

**CIDR** bit masks are most likely: 24, 16, 8, 4, 2

```
0.0.0.0/0  # selects all IP addresses

```