Azure Classroom Series – 20/Aug/2020

Azure VMSS Concepts

  • VMSS Orchestration Modes:
    • ScaleSetVMs: VMs can be added based only on the scaleset configuration.
    • VM: Virtual Machines outside Scaleset can be explicitly added to the VMSS
  • Scaling:
    • Scaling VMs can be done by using the metrics collected by Azure Monitor.
    • For app servers and web servers we use Percentage CPU

Azure Load Balancer

  • Components:
    1. Frontend IP Configuration: This is ip address of load balancer and this can be public/private (Internet facing/internal) ip address
    2. Backend pool: This is group of vms in a vmss that can serve your application
    3. Health Probes: this is a probe (check) to determine the health status of vm in vmss.
    4. Loadbalancer rules: This is used to define how incoming traffic is distributed to all instances in be pool.
    5. Inbound NAT Rule: This rule forwards incoming traffic sent to frontend ip address and port combination to specific virtual machine. By default an ssh rule is created to login into vm.
  • Load Balancer SKUs:
    • Standard Load Balancer:
      • Supports upto 1000 instances
      • BE Pool: Any virtual machines or vmss in a single virtual network
      • Health Probes: TCP, HTTP, HTTPS
      • Availability Zones: Supported
      • Secure by default: All the inbound flows unless allowed by network security group are closed
    • Basic Load Balancer
      • supports upto 300 instances
      • BE Pool: Virtual machines in single availability set or virtual machine scale set
      • Health Probes: TCP, HTTP
      • Availability Zones: Not Supported
      • Open by default. Network security group is optional

Azure VMSS Steps

  1. Create a VM Image
  2. Creating a Azure VMSS with the VM Image created in step 1
  3. Add the load balancer details
  4. login into vm instance and execute the following command
stress --cpu 8 --io 4 --vm 2 --vm-bytes 128M --timeout 100m -v
  1. Watch out for vmss instances for the next 5 minutes


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