/terraform_vmss_from_image_with_multi_ag

Primary LanguagePython

Azure VMSS Lifecycle Hook

This feature enables users to conduct a graceful shutdown on VMSS instance, when it is targeted for deletion. This provides huge flexibility for exceptional case handling on customer code.

Overall Architecture

Architecture Image Prerequisite

  • The subscription must opt in for this feature.
  • EnablePendingDeletion=true tag configured on the VMSS.

Overall Procedure

Architecture Image

Core components

Web Service - healthprobe_flask Architecture Image

Delete VMSS Instance - delete_vmss_instance Architecture Image

Deployment

Environment

Overall evnironment will be deployed from terraform with following characteristics.

  • Availability Zone: not considered.
  • PublicLB: deployed with a NAT rule for ssh.
  • MSI: Enabled and configured as contributor on resource group.
  • Custom Extension: read bootstrap file.
  • VMSS scale-in policy: NewestVM, configured from the portal.
  • Application Gateway: Backend pool and custom probe configured for this VMSS.
  • Applictions: Written in python, leverages Azure REST API and Azure SDK for python.
  • Managed Image: Managed Image, which has data disk will be referred.
  • VMID : Numeric id of VMSS instance is parsed from "name" of IMDS from each VMSS instance.
  • Data Drive formatting : setup.sh has the code for fdisk and making an entry in /etc/fstab.
  • Managed Image : a managed image will be retrieved for provisioning of VMSS instance.
  • Versioning : This code supersedes https://github.com/bedro96/terraform_vmss_ag

Terraform

Clone this git and modify terraform.tfvars as required. Execute following commands to deploy the environment.

terraform init
terraform plan -out=vmss_ag.out
terraform apply vmss_ag.out