Azure VM Images

• Generalization:
  • In this VM Image will not have user specific information
  • The user information is set while creating a VM
  • On the first boot you can set the hostname, admin user and other vm specific configuration.
  • These images contain the Azure agent, this aggent will process the parameters and signal back to the platform that the initial configuration has completed. This process is called as provisioning.
  • Provisioning in linux requires
    • Azure Linux Agent
    • Cloud init
• Specialization:
  • These are the images that are completely configured and do not require VM or special parameters.
  • The platform will turn the VM on and you will need to handle uniqueness within the vm like setting the host name etc.
• Azure VM Images can be stored in the following two ways
  • Managed Images:
    • Can be used to create multiple VMs, but they have a lot of limitations.
    • Managed Images can be created from a generlized source.
    • They can only be used to create VMs in the same region and they can’t be shared across subscriptions and tenants
  • Azure Compute Gallery
    • This is recommended for creating managing and sharing the images at scale.
    • Azure Compute Gallery helps build structure and organization around your images
      • Supports both Generalized and specialized Images
      • Global replication of Image
      • Versioning and Grouping of images for easier management
      • Sharing across subscriptions and even between tenants using Azure RBAC
    • At a high level, you create a gallery and it is made up of
      • Image definition: container that holds group of images
      • Image version: These are actual images
• Gen 1 vs Gen 2 VM Refer Here
• Sources for Creating VM Images
  • VM
  • Create an Image from a disk backup (VM Snapshot)
  • External tools like Packer Refer Here
  • Azure Image Builder
• Create a VM Image from Azure Portal
  
  
  
  
  
  
  
• Now lets create a vm with the vm image
  
  
  
  
• Exercise: Create a new resource group and create a windows vm (Windows Server 2016) and install IIS server. Refer Here
  • Store the vm image in the image gallery with new image defintion and version.