ELB
ELB (Elastic Load Balancer)
Evenly distributes incoming web traffic across multiple EC2 instances in multiple availability zones.
This increases fault tolerance of apps
ELB detects unhealthy instances and routes traffic only to healthy instances.
Free tier is NOT available for ELB.
How are you charged for using ELB
each hour or partial hour the load balancer is running
for each GB of data transferred through the load balancer
Auto Scaling
A tool that can automate scale-in and scale-out of EC2 instances based on traffic demands.
scaling in and out => adds and removes instances
scaling up and down => adds additional resources like memory/disk to existing instances
Autoscaling groups
Auto scaling happens based on thresholds.
Autoscaling components
Launch configuration
EC2 template used when auto scaling needs to add an additional server to auto scaling group
Auto scaling group
all the rules and settings that govern when EC2 server is automatically added or removed
Pricing
Auto scaling is free to use.But you will be charged for resources that Auto Scaling provision (e.g. EC2 instances that go beyond Free Tier allotment)
How to create
create launch configuration
create auto scaling group using launch configuration
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