EC2
EC2 (Virtual machine)
"basic computer/server", "instance". Use it for what ever you like.
Elastic Compute Cloud => EC2
Purchasing options
On-Demand
most expensive, most flexible (billed by hour)
Reserved
Purchase an instance for a set period of time for 1 or 3 years
you have a big discount
it does not matter whether you use it or not => you pay
Spot
unused instances are sold by amazon with a discount for short time
spot prices fluctuate
you are charged by the minute
when you have a bid => instance is provisioned for you when the spot price =< your bid
AMI (Amazon Machine images)
AMI = EC2 + operating system + software packages + settings
This is a template to quickly spin up EC2 instances based on defined AMI. (analog is a docker image and docker containers)
AMI components
Root volume template
operating system (e.g. Amazon linux)
application software (e.g. Apache web server)
Launch permissions (who is allowed to launch)
Block device mapping
EBS (hard drive mapping)
Available AMIs
Community AMI
free to use (but it is mainly a choice of OS)
AWS marketplace AMI
payed (may be with special vendor software)
My AMI
create yourself
Instance types
This is a CPU of your instance (hardware of the instance). E.g. t2.nano, t2.micro, t2.large, t2.xlarge, etc
EBS (Elastic Block Store)
EBS is a storage volume for an EC2 instance (think of hard drive).
EBS Snapshot
A snapshot is an image of EBS volume that can be stored as a backup of the volume or used to create a duplicate.
A snapshot is not an active EBS volume => you can not attach/detach it to EC2 instance
To restore a snapshot you need to create a new EBS volume using the snapshot as its template.
IOPS
Input/Output operations per second. (in KiB)
Amount of data that can be written to or retrieved from EBS per second.
Each EC2 instance must have a root volume, which may or may not be EBS.
Security groups
Security groups are similar to NACL, but Security groups are found on instance level.
Security groups are stateful
if traffic could reach an instance through SG rule => the traffic will be able to leave SG even if there is no matching outbound SG rule
SG does not have numbers comparing to NACL rule numbers
Up to five (5) security groups can be assigned per instance.
IP addressing
It is providing an EC2 instance with a public IP address.
private IP address
by default all EC2 instances have a it
it allows instances to communicate with each other as long as they are located in the same VPC (private network)
public IP address
EC2 instances can be launched with/without it depending on VPC/subnet settings
Public IP addresses are required for the instance to communicate with a internet
default VPC and subnets are configured so that any new instance that is provisioned has a public IP
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