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
- Managed 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.
