Auto Scaling
- Lets create an Auto Scaling Group with an AMI (apache2, php and stress)
- Create a Launch Configuration by selecting
- AMI
- Instance type
- Storage
- Security Group
- KeyPair
- Create AutoScaling Group linked with Launch Configuration
- Configure Increase Scenario (eg average cpu utilization > 75 for period of 5 minutes)
- Configure Decrease Scenario (eg average cpu utilization <= 50 for period of 5 minutes)
- Then you should see the machine running
- Login into one machine to create artificial load using stress
stress --cpu 8 --io 4 --vm 2 --vm-bytes 128M -v --timeout 10m
- To have a closer look, create one more ssh login session and execute htop and observe cpu
Load Balancers
- With Auto scaling group, you will have multiple servers where your application is running, we need to give unique ip/dns to the user
- For this we go with load Balancers
- In AWS, we have three kinds of Load balancers
- Classic Load Balancer : Layer 4 and Layer 7
- Application Load Balancer: Layer 7
- Network Load Balancer: Layer 4
- Load Balancer needs to know which machines are healthy, to do this we have health checks
- Generally there are two kinds of LBs
- Layer-4 Loadbalancers: LBs which are aware of ip and port
- Layer-7 Loadbalancers: LB which are aware of http,url, ip and port
- Refer here
- Create a Classic Load balancer by configuring health checks
- Access the appplication using classic loadbalancers dns name.
