What Is Azure Resource Manager (ARM)?
Azure Resource Manager, or ARM, is a Microsoft Azure service that allows users to deploy, manage, and monitor Azure resources. ARM simplifies the process of creating and organizing Azure resources, including virtual machines, SQL databases, and storage accounts.
Technically, ARM is a layer that allows for the creation, update, and deletion of resources within an Azure account. When users send requests to Azure, regardless of the method—Azure Portal, PowerShell, SDKs, or RESTful API—they are communicating with the ARM endpoint, not the individual Azure services. This establishes a consistent management practice across all Azure services. ARM utilizes resource providers specific to various Azure services to execute these operations.
For example, when creating a virtual machine, ARM liaises with the Microsoft.Compute resource provider. Rather than requiring users to detail each provisioning step, ARM employs a declarative syntax, often in the form of ARM templates, where users define their desired state, and ARM orchestrates the necessary provisioning.
A key capability of ARM is consistent state management. If a multi-resource deployment encounters an error, ARM can automatically revert the changes, ensuring environments aren’t left half-configured. Additionally, ARM integrates seamlessly with Azure Active Directory, which enables it to uphold access controls and policies, ensuring the right permissions for users and services.
This is part of a series of articles about Azure automation
In this article:
- Key Concepts of Azure Resource Manager
- 5 Key Features and Capabilities of Azure Resource Manager
- ARM Best Practices: Creating the Perfect ARM Template
Key Concepts of Azure Resource Manager
In the Azure context, a resource is an entity you need to automate. For example, it can be a database server, a virtual machine, a storage account, or any other service instance that you can create or configure in Azure.
Each resource in Azure has some common properties like name and type, which help identify what the resource is. Additionally, they have location properties to specify where they are stored or run. Some resources have additional properties unique to their type. For example, a virtual machine will have properties like size and operating system image.
Resource groups serve as logical containers in which Azure resources are deployed and managed. For instance, you could have a resource group for your production environment and another for your test environment.
Resource groups provide a way to collectively monitor, control access, provision, and manage billing for resources.
Resource providers are services that supply the resources you can deploy and manage through Azure Resource Manager. Each resource provider offers a set of resource types and operations that you can use within your applications.
For example, Microsoft.Compute is a resource provider that offers types like virtual machines, virtual machine scale sets, and availability sets. Microsoft.Storage is another resource provider that offers types like storage accounts and blob services. ARM uses these providers to create, update, delete, or retrieve resources in your Azure environment.
ARM templates are JSON files that define the resources you need to deploy for your solution. They provide a declarative way to define your intention to deploy a workload. The templates let you specify the resources to deploy, the location to deploy them, and the desired order of deployment.
ARM templates are idempotent, meaning you can run them multiple times, and they will always produce the same result. This feature makes ARM templates very useful for reliable infrastructure automation.
You can deploy any combination of resources in Azure using ARM templates. You can specify the order of resource deployment and even deploy resources to different resource groups and Azure subscriptions in a single operation. ARM also provides safety checks during deployments, ensuring your resources are correctly configured before deployment.
5 Key Features and Capabilities of Azure Resource Manager
1. Consistent Management Layer
Azure Resource Manager provides a consistent management layer, which means that regardless of how you interact with Azure, be it through the Azure portal, PowerShell, REST APIs, or client SDKs, you are interacting through ARM. This consistency ensures that you always have the same set of capabilities and the same user experience, regardless of your interface choice.
The consistent management layer creates a unified and streamlined user experience, reducing the learning curve for new users. It also simplifies resource management, as the same operations and commands apply across all Azure resources.
2. Tagging Capabilities
Tags are name-value pairs that you can assign to your Azure resources. They allow you to categorize resources based on your organizational needs, making it easier to manage and monitor your resources.
For instance, you can tag resources based on cost centers, projects, or environments. This allows you to filter and report on your Azure resources more effectively. Moreover, you can use tags to automate operations, such as shutting down all VMs tagged as ‘Test’ at the end of the day to save costs.
3. Template-Driven Deployment and Automation
Azure Resource Manager supports template-driven deployment and automation. This feature allows you to define infrastructure as code (IaC), which can then be version-controlled, tested, and deployed as part of your continuous integration/continuous deployment (CI/CD) pipelines.
ARM templates are JSON files that define the resources needed for your applications. They provide a declarative way to define your Azure resources, allowing you to specify what you want to deploy without having to write the sequence of programming commands to create it. This leads to more reliable and repeatable deployments.
Learn more in our detailed guide to azure automanage (coming soon)
4. Role-Based Access Control (RBAC) Integration
ARM integrates with Azure’s Role-Based Access Control (RBAC), allowing you to manage who has access to your Azure resources and what they can do with them. RBAC enforces your organization’s access policies by ensuring that only authorized users can perform certain actions on your resources.
With RBAC, you can assign specific roles to users, groups, and applications at certain scopes. For example, you can assign the ‘Reader’ role to a user at the subscription level, allowing them to view all resources in the subscription but not make any changes.
5. Grouping Related Resources
ARM resource groups allow you to manage and monitor related resources as a single entity. For example, if you have multiple resources that are part of the same application, you can group them together into a single resource group.
Resource groups allow you to manage the lifecycle of related resources together, making it easier to monitor and manage your Azure environment. Additionally, you can apply consistent policies and access controls to the entire group, enhancing security and compliance.
ARM Best Practices: Creating the Perfect ARM Template
Now that we understand ARM’s key capabilities, let’s review a few best practices that can help you create effective ARM templates.
Modularize Templates for Reuse
Modularizing templates involves them breaking into smaller, reusable components. Modularization not only makes the templates easier to manage and maintain but also promotes reusability.
Moreover, modularization also enhances the clarity and readability of the templates, making it easier for other developers to understand and work with them. It also allows for better testing, as each module can be tested independently before being combined into a larger system.
Use Parameters and Variables
Parameters allow for the customization of templates, as they can take on different values for different deployments. Variables are used to simplify complex expressions and to define values that are used multiple times within a template.
Using parameters and variables efficiently can greatly enhance the flexibility and maintainability of the templates. It allows for the easy adjustment of templates to fit different deployment scenarios, and it reduces the chances of errors by minimizing the amount of hard-coded values.
Implement Dependencies with the dependsOn Property
ARM templates also support the declaration of dependencies between resources through the dependsOn property. This allows for the proper sequencing of resource deployment, ensuring that a resource is only deployed after its dependencies are successfully deployed. This can improve reliability and efficiency for complex deployments.
Handle Secrets Securely
Secrets, such as passwords and connection strings, should never be stored in plain text within ARM templates. Instead, they should be stored securely in Azure Key Vault (or any other secret management system), and then referenced in the templates.
Handling secrets securely not only protects sensitive information from unauthorized access but also ensures compliance with regulatory standards. It also allows for the centralized management of secrets, making it easier to update and rotate them as needed.
Store Templates in Source Control
Source control allows for the tracking of changes to your templates over time, providing a clear history of who made what changes and when. It also facilitates collaboration among developers, as they can work on different parts of the templates without stepping on each other’s toes.
Maintaining templates in source control also provides a safety net, as it allows for the easy rollback of changes in case something goes wrong. It also enables the automation of deployments, as the templates can be automatically deployed whenever changes are pushed to the source control repository.
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