Azure Classroomnotes 01/Oct/2022

Immutable Infrastructure

• Changes in the Infra are not allowed directly.
• Any changes required have to be done by provisioning i.e. create a new image for VMSS (Azure)/ASG (AWS)
  
• The creation of Images in cloud is manual so far (what we have learn).
• If we automate the Image creation and if it is triggered by ci/cd pipeline, then we can use this for deployments
• Creating VM Images is specific to Cloud, hashicorp released a tool called as Packer which is used for image creations is various virtual environments
• The ideal workflow could be
  

Packer

• Refer Here for the official documentation.
• Packer can be configured in json/HCL (Hashicorp configuration language)
• Terminology:
  • Builder: This is where you want to create image
  • Provisioning: This is where we install the necessary applications which should be part of vm. Here Shell/Powershell/Ansible/Chef etc are supported.
• Installation:
• Download the packer Refer Here
• unzip and add the folder to the environment variable PATH
  

Scenario 1: Create a hello-world image

• Json template Refer Here
• To build a image in AWS we need to figure out builder Refer Here
• Refer Here for ebs
• Generally for builders authentication needs to be setup
• Refer Here for the changeset containing azure and aws image creation
• Using Variables in template: Refer Here
• Exercise: Complete the script to create php info image with variable version. Refer Here
• Azure: Refer Here for the documentation from microsoft to use azure

Load Balancer

• The OSI Model
  
• Layer wise functionality
  
• Transport Layer => Level 4:
  • Ip address
  • port
  • TCP/UDP
• Application Layer => Level 7:
  • http:
    • paths in urls => Routes
    • headers
  • ssl
  • Ip address
  • port
  • TCP/UDP
    
    
• Layer 4 LB in Azure => Azure Load Balancer
• Layer 4 LB in AWS => Network Load Balancer
• Path Based Routing in Layer 7
  
• Header based routing in Layer 7