Azure Service Endpoints provide secure and direct connectivity between a Virtual Network (VNet) and Azure services over the Azure backbone network.
They allow resources in a VNet to communicate with Azure services (e.g., Azure Storage, Azure SQL Database) without requiring a public IP address, improving both security and performance.
Key Features of Service Endpoints
1. Enhanced Security
Restricts service access to specific VNet subnets, ensuring traffic never leaves the Azure backbone.
2. Improved Performance
Eliminates the need for traffic to travel via public IPs, reducing latency and optimizing routing.
3. Simplified Access Control
Integration with Azure service-level firewall and access controls to specify VNet and subnet access.
How Service Endpoints Work
When a Service Endpoint is enabled for a subnet, Azure dynamically updates the route table for that subnet to direct traffic for the selected service to the Azure backbone network.
Azure services recognize requests coming from a Service Endpoint-enabled subnet and apply access policies configured for that VNet.
Supported Azure Services
Service Endpoints can be used with the following Azure services (partial list):
Azure Storage (Blob, Table, Queue, File)
Azure SQL Database and Managed Instance
Azure Key Vault
Azure Cosmos DB
Azure App Service
Azure Data Lake
Azure Event Hubs
Azure Service Bus
Each service may have specific considerations for Service Endpoint configuration.
How to Enable Service Endpoints
1. Virtual Network Configuration
Scope: Service Endpoints are configured at the subnet level in a VNet.
You can enable multiple Service Endpoints for the same subnet (e.g., for both Azure Storage and SQL).
2. Service Access Restrictions
By default, Azure services are accessible from any internet-connected network.
After enabling Service Endpoints, you can configure the service to restrict access only to your VNet/subnets.
Steps to Enable Service Endpoints
1. Enable on the Subnet
Go to the VNet in the Azure Portal.
Select Subnets → Choose a subnet → Click + Service Endpoints.
Select the Azure service(s) you want to enable (e.g., Microsoft.Storage).
Specify the regions where the service is hosted.
Save changes.
2. Restrict Access on the Service
Go to the Azure resource (e.g., a Storage Account).
Under Networking, select Selected Networks.
Add your VNet and subnet to the list of allowed networks.
Service Endpoint Use Case Example
Scenario
You want to restrict access to an Azure Storage account so that only VMs in a specific subnet can access it.
Solution
Enable Service Endpoint for Azure Storage on the target subnet.
Update the Storage Account’s firewall settings:
Set Selected Networks and add your VNet and subnet to the allowed list.
Deploy a VM in the subnet and test access:
The VM can access the Storage Account without a public IP, while requests from outside the VNet are denied.
Advantages of Service Endpoints
1. Secure Connectivity
All traffic to the Azure service remains on Azure's private backbone, reducing exposure to internet-based threats.
2. No Public IP Required
Resources in the VNet don’t need public IPs to communicate with Azure services.
3. Cost Efficiency
No additional cost for enabling Service Endpoints, though the Azure service usage charges still apply.
4. Simple Configuration
Easily enabled at the subnet level with minimal setup.
Limitations of Service Endpoints
1. Regional Dependency
The service must be available in the same region as the VNet's subnet.
2. Applies to Subnets, Not Individual Resources
Service Endpoints apply to an entire subnet, not to individual resources within the subnet.
3. No Cross-Region Support
Service Endpoints are region-specific. For cross-region access, other mechanisms like Private Link are recommended.
4. Not for On-Premises
Service Endpoints work only within Azure; on-premises traffic to Azure services still requires public IPs or VPN/ExpressRoute.
Service Endpoints vs. Private Endpoints
| Feature | Service Endpoints | Private Endpoints |
|---|---|---|
| Traffic Path | Azure backbone network. | Azure backbone with a private IP in your VNet. |
| Scope | Subnet level. | Individual resource level. |
| Cross-Region Support | No (region-specific). | Yes (can connect to resources in other regions). |
| On-Premises Access | Not supported (needs public IP or VPN). | Supported via private IP and DNS resolution. |
| Use Case | Simple access control for Azure services in the VNet. | Isolated, granular access to specific resources. |
Best Practices for Service Endpoints
1. Restrict Service Access
After enabling Service Endpoints, always configure the Azure service to allow only specific VNets and subnets.
2. Combine with NSGs
Use Network Security Groups (NSGs) to further control traffic within the VNet.
3. Monitor Traffic
Use Azure Monitor to track and audit access to the service.
4. Avoid Overuse
If you require high isolation or cross-region connectivity, consider Azure Private Link instead.
Summary
Service Endpoints in Azure provide a secure, efficient, and cost-effective way to connect VNets to Azure services.
While they are ideal for basic scenarios where resources in the same region need access, for more advanced requirements like cross-region connectivity or tighter resource-level control, Azure Private Link may be a better choice.
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