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)
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  • 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
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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
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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
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  • Layer wise functionality
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  • 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
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  • Layer 4 LB in Azure => Azure Load Balancer
  • Layer 4 LB in AWS => Network Load Balancer
  • Path Based Routing in Layer 7
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  • Header based routing in Layer 7
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