How to use Azure API Management with virtual networks
Azure Virtual Networks (VNETs) allow you to place any of your Azure resources in a non-internet routeable network that you control access to. These networks can then be connected to your on-premises networks using various VPN technologies. To learn more about Azure Virtual Networks start with the information here: Azure Virtual Network Overview.
Azure API Management can be deployed inside the virtual network (VNET), so it can access backend services within the network. The developer portal and API gateway, can be configured to be accessible either from the Internet or only within the virtual network.
Azure API Management supports both classic and Azure Resource Manager VNets.
This article has been updated to use the new Azure PowerShell Az module. You can still use the AzureRM module, which will continue to receive bug fixes until at least December 2020. To learn more about the new Az module and AzureRM compatibility, see Introducing the new Azure PowerShell Az module. For Az module installation instructions, see Install Azure PowerShell.
This feature is available in the Premium and Developer tiers of API Management.
To perform the steps described in this article, you must have:
An active Azure subscription.
An APIM instance. For more information, see Create an Azure API Management instance.
Enable VNET connectivity using the Azure portal
Navigate to your APIM instance in the Azure portal.
Select Virtual Network.
Configure the API Management instance to be deployed inside a Virtual network.
Select the desired access type:
External: the API Management gateway and developer portal are accessible from the public internet via an external load balancer. The gateway can access resources within the virtual network.
Internal: the API Management gateway and developer portal are accessible only from within the virtual network via an internal load balancer. The gateway can access resources within the virtual network.
You will now see a list of all regions where your API Management service is provisioned. Select a VNET and subnet for every region. The list is populated with both classic and Resource Manager virtual networks available in your Azure subscriptions that are setup in the region you are configuring.
Service Endpoint in the above diagram includes Gateway/Proxy, the Azure portal, the Developer portal, GIT, and the Direct Management Endpoint. Management Endpoint in the above diagram is the endpoint hosted on the service to manage configuration via Azure portal and Powershell. Also, note, that, even though, the diagram shows IP Addresses for its various endpoints, API Management service only responds on its configured Hostnames.
When deploying an Azure API Management instance to a Resource Manager VNET, the service must be in a dedicated subnet that contains no other resources except for Azure API Management instances. If an attempt is made to deploy an Azure API Management instance to a Resource Manager VNET subnet that contains other resources, the deployment will fail.
Click Save in the top navigation bar.
Click Apply network configuration in the top navigation bar.
The VIP address of the API Management instance will change each time VNET is enabled or disabled. The VIP address will also change when API Management is moved from External to Internal or vice-versa
If you remove API Management from a VNET or change the one it is deployed in, the previously used VNET can remain locked for up to two hours. During this period it will not be possible to delete the VNET or deploy a new resource to it.
You can also enable VNET connectivity using the PowerShell cmdlets
Create an API Management service inside a VNET: Use the cmdlet New-AzApiManagement to create an Azure API Management service inside a VNET.
Deploy an existing API Management service inside a VNET: Use the cmdlet Update-AzApiManagementRegion to move an existing Azure API Management service inside a Virtual Network.
After your API Management service is connected to the VNET, accessing backend services within it is no different than accessing public services. Just type in the local IP address or the host name (if a DNS server is configured for the VNET) of your web service into the Web service URL field when creating a new API or editing an existing one.
Following is a list of common misconfiguration issues that can occur while deploying API Management service into a Virtual Network.
- Custom DNS server setup: The API Management service depends on several Azure services. When API Management is hosted in a VNET with a custom DNS server, it needs to resolve the hostnames of those Azure services. Please follow this guidance on custom DNS setup. See the ports table below and other network requirements for reference.
If you plan to use a Custom DNS Server(s) for the VNET, you should set it up before deploying an API Management service into it. Otherwise you need to update the API Management service each time you change the DNS Server(s) by running the Apply Network Configuration Operation
- Ports required for API Management: Inbound and Outbound traffic into the Subnet in which API Management is deployed can be controlled using Network Security Group. If any of these ports are unavailable, API Management may not operate properly and may become inaccessible. Having one or more of these ports blocked is another common misconfiguration issue when using API Management with a VNET.
|Source / Destination Port(s)||Direction||Transport protocol||Service Tags
Source / Destination
|Purpose (*)||Virtual Network type|
|* / 80, 443||Inbound||TCP||INTERNET / VIRTUAL_NETWORK||Client communication to API Management||External|
|* / 3443||Inbound||TCP||ApiManagement / VIRTUAL_NETWORK||Management endpoint for Azure portal and Powershell||External & Internal|
|* / 80, 443||Outbound||TCP||VIRTUAL_NETWORK / Storage||Dependency on Azure Storage||External & Internal|
|* / 80, 443||Outbound||TCP||VIRTUAL_NETWORK / AzureActiveDirectory||Azure Active Directory (where applicable)||External & Internal|
|* / 1433||Outbound||TCP||VIRTUAL_NETWORK / SQL||Access to Azure SQL endpoints||External & Internal|
|* / 5672||Outbound||TCP||VIRTUAL_NETWORK / EventHub||Dependency for Log to Event Hub policy and monitoring agent||External & Internal|
|* / 445||Outbound||TCP||VIRTUAL_NETWORK / Storage||Dependency on Azure File Share for GIT||External & Internal|
|* / 1886||Outbound||TCP||VIRTUAL_NETWORK / INTERNET||Needed to publish Health status to Resource Health||External & Internal|
|* / 443||Outbound||TCP||VIRTUAL_NETWORK / AzureMonitor||Publish Diagnostics Logs and Metrics||External & Internal|
|* / 25||Outbound||TCP||VIRTUAL_NETWORK / INTERNET||Connect to SMTP Relay for sending e-mails||External & Internal|
|* / 587||Outbound||TCP||VIRTUAL_NETWORK / INTERNET||Connect to SMTP Relay for sending e-mails||External & Internal|
|* / 25028||Outbound||TCP||VIRTUAL_NETWORK / INTERNET||Connect to SMTP Relay for sending e-mails||External & Internal|
|* / 6381 - 6383||Inbound & Outbound||TCP||VIRTUAL_NETWORK / VIRTUAL_NETWORK||Access Azure Cache for Redis Instances between RoleInstances||External & Internal|
|* / *||Inbound||TCP||AZURE_LOAD_BALANCER / VIRTUAL_NETWORK||Azure Infrastructure Load Balancer||External & Internal|
The Ports for which the Purpose is bold are required for API Management service to be deployed successfully. Blocking the other ports however will cause degradation in the ability to use and monitor the running service.
SSL functionality: To enable SSL certificate chain building and validation the API Management service needs Outbound network connectivity to ocsp.msocsp.com, mscrl.microsoft.com and crl.microsoft.com. This dependency is not required, if any certificate you upload to API Management contain the full chain to the CA root.
DNS Access: Outbound access on port 53 is required for communication with DNS servers. If a custom DNS server exists on the other end of a VPN gateway, the DNS server must be reachable from the subnet hosting API Management.
Metrics and Health Monitoring: Outbound network connectivity to Azure Monitoring endpoints, which resolve under the following domains:
Azure Environment Endpoints Azure Public
azure region.warm.ingestion.msftcloudes.com where
East US 2is eastus2.warm.ingestion.msftcloudes.com
SMTP Relay: Outbound network connectivity for the SMTP Relay, which resolves under the host
Developer portal CAPTCHA: Outbound network connectivity for the developer portal's CAPTCHA, which resolves under the host
Azure portal Diagnostics: To enable the flow of diagnostic logs from Azure portal when using the API Management extension from inside a Virtual Network, outbound access to
dc.services.visualstudio.comon port 443 is required. This helps in troubleshooting issues you might face when using extension.
Force Tunneling Traffic to On-prem Firewall Using Express Route or Network Virtual Appliance: A common customer configuration is to define their own default route (0.0.0.0/0) which forces all traffic from the API Management delegated subnet to flow through an on-premises firewall or to an Network virtual appliance. This traffic flow invariably breaks connectivity with Azure API Management because the outbound traffic is either blocked on-premises, or NAT'd to an unrecognizable set of addresses that no longer work with various Azure endpoints. The solution requires you to do a couple of things:
Enable service endpoints on the subnet in which the API Management service is deployed. Service Endpoints need to be enabled for Azure Sql, Azure Storage, Azure EventHub and Azure ServiceBus. Enabling endpoints directly from API Management delegated subnet to these services allows them to use the Microsoft Azure backbone network providing optimal routing for service traffic. If you use Service Endpoints with a forced tunneled Api Management, the above Azure services traffic isn't forced tunneled. The other API Management service dependency traffic is forced tunneled and can't be lost or the API Management service would not function properly.
All the control plane traffic from Internet to the management endpoint of your API Management service are routed through a specific set of Inbound IPs hosted by API Management. When the traffic is force tunneled the responses will not symmetrically map back to these Inbound source IPs. To overcome the limitation, we need to add the following user-defined routes (UDRs) to steer traffic back to Azure by setting the destination of these host routes to "Internet". The set of Inbound IPs for control Plane traffic is as follows:
126.96.36.199/32, 188.8.131.52/32, 184.108.40.206/32, 220.127.116.11/32, 18.104.22.168/32, 22.214.171.124/32, 126.96.36.199/32, 188.8.131.52/32, 184.108.40.206/32, 220.127.116.11/32, 18.104.22.168/32, 22.214.171.124/32
For other API Management service dependencies which are force tunneled, there should be a way to resolve the hostname and reach out to the endpoint. These include
- Metrics and Health Monitoring
- Azure portal Diagnostics
- SMTP Relay
- Developer portal CAPTCHA
Initial Setup: When the initial deployment of API Management service into a subnet does not succeed, it is advised to first deploy a virtual machine into the same subnet. Next remote desktop into the virtual machine and validate that there is connectivity to one of each resource below in your azure subscription
- Azure Storage blob
- Azure SQL Database
- Azure Storage Table
After you have validated the connectivity, make sure to remove all the resources deployed in the subnet, before deploying API Management into the subnet.
Incremental Updates: When making changes to your network, refer to NetworkStatus API, to verify that the API Management service has not lost access to any of the critical resources, which it depends upon. The connectivity status should be updated every 15 minutes.
Resource Navigation Links: When deploying into Resource Manager style vnet subnet, API Management reserves the subnet, by creating a resource navigation Link. If the subnet already contains a resource from a different provider, deployment will fail. Similarly, when you move an API Management service to a different subnet or delete it, we will remove that resource navigation link.
Azure reserves some IP addresses within each subnet, and these addresses can't be used. The first and last IP addresses of the subnets are reserved for protocol conformance, along with three more addresses used for Azure services. For more information, see Are there any restrictions on using IP addresses within these subnets?
In addition to the IP addresses used by the Azure VNET infrastructure, each Api Management instance in the subnet uses two IP addresses per unit of Premium SKU or one IP address for the Developer SKU. Each instance reserves an additional IP address for the external load balancer. When deploying into Internal vnet, it requires an additional IP address for the internal load balancer.
Given the calculation above the minimum size of the subnet, in which API Management can be deployed is /29 which gives three IP addresses.
- A load balanced public IP address (VIP) will be reserved to provide access to all service endpoints.
- An IP address from a subnet IP range (DIP) will be used to access resources within the vnet and a public IP address (VIP) will be used to access resources outside the vnet.
- Load balanced public IP address can be found on the Overview/Essentials blade in the Azure portal.
- A subnet containing API Management instances cannot contain any other Azure resource types.
- The subnet and the API Management service must be in the same subscription.
- A subnet containing API Management instances cannot be moved across subscriptions.
- For multi-region API Management deployments configured in Internal virtual network mode, users are responsible for managing the load balancing across multiple regions, as they own the routing.
- Connectivity from a resource in a globally peered VNET in another region to API Management service in Internal mode will not work due to platform limitation. For more information, see Resources in one virtual network cannot communicate with Azure internal load balancer in peered virtual network
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