Note_Tech

All technological notes.

Project maintained by simonangel-fong Hosted on GitHub Pages — Theme by mattgraham

AWS - EC2

Back

AWS - EC2

`Amazon EC2`

Amazon EC2:
- Elastic Compute Cloud
- Infrastructure as a Service
It mainly consists in the capability of :
- Renting virtual machines (EC2)
- Storing data on virtual drives (EBS)
- Distributing load across machines (ELB)
- Scaling the services using an auto-scaling group (ASG)

EC2 sizing & configuration options

Operating System (OS): Linux, Windows or Mac OS
How much compute power & cores (CPU)
How much random-access memory (RAM)
How much storage space:
- Network-attached (EBS & EFS)
- hardware (EC2 Instance Store)
Network card: speed of the card, Public IP address
Firewall rules: security group
Bootstrap script (configure at first launch): EC2 User Data

EC2 Instance Types

Naming convention: [instance_class][generation].[size]
- eg: m5.2xlarge, t2.micro
different types of EC2 instances that are optimised for different use cases
- ref: https://aws.amazon.com/ec2/instance-types/

Type	Feature	Use Case	Example
General Purpose	for a diversity of workloads	web servers	`t2`
Compute Optimized	for compute-intensive tasks	ML, Gaming server	`C6g`
Memory Optimized	for workloads that process large data sets in memory	In-memory databases	`R5`
Storage Optimized	for intensive access to large data sets on local storage	OLTP	`I3`

Purchasing Options

Option	Feature
On-Demand Instances	short workload, predictable pricing, pay by second
Reserved (1 & 3 years) - Reserved	long workloads
Reserved (1 & 3 years) - Convertible Reserved Instances	long workloads with flexible instances
Savings Plans (1 & 3 years)	commitment to an amount of usage, long workload
Spot Instances	short workloads, cheap, can lose instances (less reliable)
Dedicated Hosts	book an entire physical server, control instance placement
Dedicated Instances	no other customers will share your hardware
Capacity Reservations	reserve capacity in a specific AZ for any duration

On Demand

Pay for what you use:
- Linux or Windows - billing per second, after the first minute
- All other operating systems - billing per hour
Has the highest cost but no upfront payment
No long-term commitment
Recommended for short-term and un-interrupted workloads, where you can’t predict how the application will behave

Reserved Instances

Up to 72% discount compared to On-demand
You reserve a specific instance attributes (Instance Type, Region, Tenancy, OS)
Reservation Period
- 1 year (+discount)
- 3 years (+++discount)
Payment Options
- No Upfront (+),
- Partial Upfront (++),
- All Upfront (+++)
Reserved Instance’s Scope
- Regional
- Zonal (reserve capacity in an AZ)
Recommended
- for steady-state usage applications (think database)
You can buy and sell in the Reserved Instance Marketplace
Convertible Reserved Instance
- Can change the EC2 instance type, instance family, OS, scope and tenancy
- Up to 66% discount

Hands-on: Reserved Instances

reserve_instance

Savings Plans

Get a discount based on long-term usage (up to 72% - same as RIs)
Commit to a certain type of usage ($10/hour for 1 or 3 years)
Usage beyond EC2 Savings Plans is billed at the On-Demand price
Locked to a specific instance family & AWS region (e.g., M5 in us-east-1)
Flexible across:
- Instance Size (e.g., m5.xlarge, m5.2xlarge)
- OS (e.g., Linux, Windows)
- Tenancy (Host, Dedicated, Default)

Hands-on: Savings Plans

ec2_saving_plan

will redirect to Cost management

saving_plan_compute

Spot Instances

Can get a discount of up to 90% compared to On-demand. Most discount
Instances that you can “lose” at any point of time if your max price is less than the current spot price
The MOST cost-efficient instances in AWS
Useful for workloads that are resilient to failure
- Batch jobs
- Data analysis
- Image processing
- Any distributed workloads
- Workloads with a flexible start and end time
Not suitable for critical jobs or databases

Spot Instance Requests

Can get a discount of up to 90% compared to On-demand
Define max spot price and get the instance while current spot price < max
- The hourly spot price varies based on offer and capacity
- If the current spot price > your max price you can choose to stop or terminate your instance with a 2 minutes grace period.
Other strategy: Spot Block
- “block” spot instance during a specified time frame (1 to 6 hours) without interruptions
- In rare situations, the instance may be reclaimed
Used for batch jobs, data analysis, or workloads that are resilient to failures.
Not great for critical jobs or databases
terminate Spot Instances:
- You can only cancel Spot Instance requests that are open, active, or disabled.
- Cancelling a Spot Request does not terminate instances
- You must first cancel a Spot Request, and then terminate the associated Spot Instance

terminate_spot_instance

Hand-on: Spot Instance Requests

EC2 > Instances > Launch an instance

spot_instances

Spot Fleets

Spot Fleets allow us to automatically request Spot Instances with the lowest price
Spot Fleets
- set of Spot Instances + (optional) On-Demand Instances
The Spot Fleet will try to meet the target capacity with price constraints
- Define possible launch pools: instance type (m5.large), OS, Availability Zone
- Can have multiple launch pools, so that the fleet can choose
- Spot Fleet stops launching instances when reaching capacity or max cost
Strategies to allocate Spot Instances:
- lowestPrice: from the pool with the lowest price (cost optimization, short workload)
- diversified: distributed across all pools (great for availability, long workloads)
- capacityOptimized: pool with the optimal capacity for the number of instances
- priceCapacityOptimized (recommended): pools with highest capacity available, then select the pool with the lowest price (best choice for most workloads)

Hands-on: Spot Fleets

EC2 > Spot requests > Request Spot Instances

spot_req

spot_Instance_pricing_history

allocation_strategy

Dedicated Hosts

A physical server with EC2 instance capacity fully dedicated to your use
Allows you address compliance requirements and use your existing server-bound software licenses (per-socket, per-core, pe—VM software licenses)
Purchasing Options:
- On-demand – pay per second for active Dedicated Host
- Reserved - 1 or 3 years (No Upfront, Partial Upfront, All Upfront)
The most expensive option
Useful
- for software that have complicated licensing model (BYOL – Bring Your Own License)
- for companies that have strong regulatory or compliance needs
Hands-on

Allocate_Dedicated_Host

Dedicated Instances

Instances run on hardware that’s dedicated to you
May share hardware with other instances in same account
No control over instance placement (can move hardware after Stop / Start)

Capacity Reservations

Reserve On-Demand instances capacity in a specific AZ for any duration
- You always have access to EC2 capacity when you need it
No time commitment (create/cancel anytime), no billing discounts
Combine with Regional Reserved Instances and Savings Plans to benefit from billing discounts
You’re charged at On-Demand rate whether you run instances or not
Suitable for short-term, uninterrupted workloads that needs to be in a specific AZ

Capacity_Reservation

Right Option

Spot instances: the hotel allows people to bid for the empty rooms and the highest bidder keeps the rooms. You can get kicked out at any time
On demand: coming and staying in resort whenever we like, we pay the full price
Reserved: like planning ahead and if we plan to stay for a long time, we may get a good discount.
Savings Plans: pay a certain amount per hour for certain period and stay in any room type (e.g., King, Suite, Sea View, …)
Capacity Reservations: you book a room for a period with full price even you don’t stay in it
Dedicated Hosts: We book an entire building of the resort

Advanced

Attach aws role to EC2 instance

After create an instance

role

Result:
- Security: instance can access aws services without keep access key in the instance.

role

User Data

It is possible to bootstrap our instances using an EC2 User data script.
bootstrapping:
- launching commands when a machine starts
- That script is only run once at the instance first start
EC2 user data is used to automate boot tasks such as:
- Installing updates
- Installing software
- Downloading common files from the internet
- Anything you can think of
The EC2 User Data Script runs with the root user. (script can skip sudo)

Hands-on: User Data

Create an EC2 as a linux server using user data

#!/bin/bash
# Use this for your user data (script from top to bottom)
# install httpd (Linux 2 version)
yum update -y
yum install -y httpd
systemctl start httpd
systemctl enable httpd
echo "<h1>Hello World from $(hostname -f)</h1>" > /var/www/html/index.html

Placement Groups

placement groups
- used to define EC2 Instance placement strategy
Strategies for the group:
- Cluster:
  - clusters instances into a low-latency group in a single Availability Zone
- Spread:
  - spreads instances across underlying hardware (max 7 instances per group per AZ)
- Partition:
  - spreads instances across many different partitions (which rely on different sets of racks) within an AZ. Scales to 100s of EC2 instances per group (Hadoop, Cassandra, Kafka)

Cluster

cluster

Same Rack, Same AZ
Pros:
- Great network (10 Gbps bandwidth between instances with Enhanced Networking enabled - recommended)
Cons:
- If the rack fails, all instances fails at the same time
Use case:
- Big Data job that needs to complete fast
- Application that needs extremely low latency and high network throughput

Spread

Different rack, same AZ or different AZ
Pros:
- Can span across Availability Zones (AZ)
- Reduced risk is simultaneous failure
- EC2 Instances are on different physical hardware
Cons:
- Limited to 7 instances per AZ per placement group
Use case:
- Application that needs to maximize high availability
- Critical Applications where each instance must be isolated from failure from each other

Partition

Different partitions, different rack.
Up to 7 partitions per AZ
Can span across multiple AZs in the same region
Up to 100s of EC2 instances
The instances in a partition do not share racks with the instances in the other partitions
A partition failure can affect many EC2 but won’t affect other partitions
EC2 instances get access to the partition information as metadata
Use cases:
- HDFS, HBase, Cassandra, Kafka

Hands-on: Placement group

EC2 > Placement groups > Create placement group

placement

Hibernate

We know we can stop, terminate instances
- Stop – the data on disk (EBS) is kept intact in the next start
- Terminate – any EBS volumes (root) also set-up to be destroyed is lost.
On start, the following happens:
- First start: the OS boots & the EC2 User Data script is run
- Following starts: the OS boots up
- Then your application starts, caches get warmed up, and that can take time!
Introducing EC2 Hibernate:
- The in-memory (RAM) state is preserved
- The instance boot is much faster! (the OS is not stopped / restarted)
- Under the hood: the RAM state is written to a file in the root EBS volume
- The root EBS volume must be encrypted
Use cases:
- Long-running processing
- Saving the RAM state
- Services that take time to initialize
Good to know
- Supported Instance Families – C3, C4, C5, I3, M3, M4, R3, R4, T2, T3, …
- Instance RAM Size – must be less than 150 GB.
- Instance Size – not supported for bare metal instances.
- AMI – Amazon Linux 2, Linux AMI, Ubuntu, RHEL, CentOS & Windows…
- Root Volume – must be EBS, encrypted, not instance store, and large
- Available for On-Demand, Reserved and Spot Instances
- An instance can NOT be hibernated more than 60 days

Hands-on: Hibernate

Enable Hibernate when creating EC2
- instance memory < EBS
- EBS Encrypted
- Advanced > Stop - Hibernate behavior: Enable

hiberante_storage

hiberante_enable

Hibernate instance

hiberante_instance

AMI

AMI: Amazon Machine Image
- a customization of an EC2 instance
- You add your own software, configuration, operating system, monitoring…
Faster boot / configuration time because all your software is pre-packaged
AMI are built for a specific region (and can be copied across regions)
You can launch EC2 instances from:
- A Public AMI:
  - AWS provided
- Your own AMI:
  - you make and maintain them yourself
- An AWS Marketplace AMI:
  - an AMI someone else made (and potentially sells)

AMI Process (from an EC2 instance)

Start an EC2 instance and customize it
Stop the instance (for data integrity)
Build an AMI – this will also create EBS snapshots
Launch instances from other AMIs

ami_diagram

Hands-on: AMI

Create

ami_create

List

ami_list

TOP