Custom VM images in Microsoft Azure offer a dynamic way to streamline virtual machine (VM) deployments and establish consistency across your cloud infrastructure. These images act as pre-configured templates containing your desired operating system, applications, and settings. Think of them as personalized templates for your virtual machines, enabling faster deployments with pre-configured settings and applications.
Why Use Custom VM Images?
- Reduced Deployment Time: Pre-configure settings and install essential software within the image to significantly speed up VM deployments.
- Standardized Environments: Ensure consistency across your VMs, simplifying management and reducing the risk of errors.
- Improved Efficiency: Automate the creation and deployment of VMs using custom images, freeing up time and resources for other tasks.
Scenarios Benefiting from Custom VM Images
- Line-of-Business Applications: Streamline deployments of specific applications across multiple VMs.
- Development and Testing Environments: Standardize environments for development teams to collaborate more effectively.
- High-Availability Clusters: Ensure consistent configurations across all cluster members for rapid VM deployments in case of failures.
Prerequisites
You must have an existing virtual machine (VM).
Key Resource Descriptions
- Image Source: A resource used to create an image version in a gallery, such as an existing Azure VM, a managed snapshot, or an image version in another gallery.
- Gallery: A repository for organizing and sharing VM apps and images, similar to the Azure Marketplace but with access control.
- Image Definition: Created within a gallery, it includes information about the image and requirements for using it (e.g., OS type, memory requirements).
- Image Version: Used to create a VM, you can have multiple versions for different needs and reuse them as required.
Steps to Create a Custom VM Image in Azure
1. Provision a VM
Log in to the Azure portal as a Global Admin and create a new VM with your desired operating system and configuration (e.g., Windows Server 2016 Datacenter).
2. Install Applications
Install all necessary applications and configure the VM according to your specific requirements (e.g., XPS Viewer, Adobe Reader, create a folder in C:).
3. Generalize the VM
Run %windir%\system32\sysprep\sysprep.exe as an administrator within the VM. In the new window, select OOBE and Generalize, and choose Shutdown as the shutdown option. This removes machine-specific details like unique IDs and hostnames, preparing the VM for image creation.
4. Capture the Image
Once the VM shuts down, go to the VM properties page in the Azure portal and click the Capture icon. Provide a name for the image, select the resource group to save the image, and choose to automatically delete this virtual machine after creating the image. Click Create.
5. Store and Distribute
After the image is created, go to All Services > Images to see the created image. Click on the image and go to its properties page, then click Create VM. Resize the VM image and change other configurations as needed. Once the VM is created, log in and verify that it includes all the customizations.
Additional Considerations
- Security: Fortify the base operating system and configure security settings directly within the image.
- Version Control: Implement version control to track changes, revert to previous versions if necessary, and maintain a history of image configurations.
- Optimization: Periodically review and update your custom images to ensure they remain efficient and incorporate the latest software versions.
