Elastic Cloud Compute

 

EC2

Features

• EC2 = Elastic Cloud Compute -> Infrastructure as a Service
• Rent virtual machines
• Store data on virtual drives (EBS)
• Load distribution across machines (ELB)
• Scaling the services using auto-scaling group (ASG)

EC2 sizing and configuration options

• OS
• CPU
• RAM
• Storage space (EBS &EFS)
• Network card speed
• Firewall rules
• Bootstrap script : EC2 user data

Bootstrapping 

• To launch commands when the machine starts
• Carried out using EC2 User data scripts
• Script runs only once at the instance's first start
• Used to automate boot tasks such as 
• install updates
• install software
• download common files from internet
• EC2 User data script runs under root user (sudo rights)

EC2 Instance Types

• General Purpose
• great for diversity of workloads (web services and code repos)
• good balance between compute, memory and networking
• example : t2.micro

• Compute Optimised
• Good for compute intensive tasks 
• batch processing workloads
• media transcoding
• high performance web servers
• high performance computing
• scientific modelling & machine learning
• dedicated gaming servers
• Example C6g, C6gn, C5, C5a, etc

• Memory Optimised
• Fast performance for workloads processing large data sets
• Use cases:
• high performance, relational/non-relational databases
• distributed web scale cache stores
• In-memory databases optimised for BI
• Apps performing real-time processing of big unstructured data
• Example : R-series, X, Z, high memory

• Storage Optimised
• Great for storage intensive tasks requiring high sequential read/write access to large data sets on local storage
• Use cases:
• high frequency online transaction processing (OLTP) systems
• relational and NoSQL databases
• Cache for in-memory databases
• Data warehousing apps
• distributed file systems
• Example : I-series, D and H

AWS naming convention : Using example of m5.2xlarge

m            : instance class

5             : generation (incremented as AWS improves them over time)

2xlarge    : size within the instance class (indicates the size of memory, cpu, etc)

 

Security Groups

• Fundamental of network security of AWS
• controls how traffic is allowed into or out of EC2 instances.
• only contain "allow" rules
• rules can reference by IP or other security groups
• act as "firewall" on EC2 instances
• they regulate :
• access to ports
• authorised IP ranges - IPv4 and IPv6
• control of inbound network 
• control of outbound network
• can be attached to multiple instances
• instances can have multiple security groups
• closely coupled with the region/VPC combination
• exists as a "firewall" outside of the EC2 instance
• Good practice to maintain one separate security group for SSH access
• if application is not accessible (time outs), its probably a security group issue
• However, "connection refused" indicates that traffic went through but application errored out or didn't launch
• By default, all inbound traffic is blocked and all outbound traffic is authorised

Classic Ports to know

• 22 = SSH (secure shell) - log into a Linux instance
• 21 = FTP - upload file into a file share
• 22 = SFTP - upload files using SSH
• 80 = HTTP - to access unsecured websites
• 443 = HTTPS - access secured websites
• 3389 = RDS (remote desktop protocol) - log into a Windows instance