Azure Relay: Unlocking Hybrid Cloud Potential

Azure Relay is a powerful tool that lets you connect your on-premises applications to cloud services like Azure and other services over the internet. It allows you to expose your on-premises applications to the cloud, making them accessible from anywhere.

With Azure Relay, you can use standard WebSockets and REST APIs to communicate with your on-premises applications, making it easy to integrate them with cloud services. This is especially useful for applications that are behind firewalls or have other connectivity issues.

Azure Relay provides a secure and reliable way to connect your on-premises applications to the cloud, using industry-standard protocols like HTTPS and WebSocket. This ensures that your data is protected and your applications can communicate securely.

Azure Relay is a fully managed service that helps you securely expose services within your corporate enterprise network to the public cloud.

It allows you to expose services without opening a firewall connection, and without requiring intrusive changes to your corporate network infrastructure. This is a huge advantage, as it reduces the complexity of setup and makes it easier to integrate your on-premises resources with Azure applications.

There are two main types of Azure Relays: Hybrid Connections and WCF Relays.

Azure Relay creates a hybrid environment where on-premises resources are accessible to Azure applications with a secure, managed connection. This is achieved through outbound connections, which provide a secure channel over which your Azure applications can communicate with on-premises resources.

Charging for Azure Relay involves more than just the relay itself. You're charged for associated data transfers for egress outside of the datacenter in which your application is provisioned.

The pricing for WCF Relay is only available in Standard tier namespaces. This means that if you're using a Standard tier namespace, you'll be charged based on the number of messages, not operations.

Relay hours are also a factor in the pricing, and you can find more information about this in the "Hybrid Connections and WCF Relays" table on the pricing details page.

To migrate a namespace to another Azure subscription, you can use the Azure portal or PowerShell commands. You must be an Administrator user on both the source and target subscriptions.

To use PowerShell, the namespace must be active, and you'll need to run a sequence of commands. This requires Administrator access on both subscriptions.

You can also use the Hybrid Connections feature in Azure Relay to integrate on-premises APIs with cloud applications. This allows cloud apps to connect to HTTP-based APIs hosted on-premises, without exposing them to the internet.

When a relay has multiple listeners connected to it, it's considered open, and adding more listeners results in additional relay hours.

A relay is considered open when at least one relay listener is connected to it. The number of relay senders that are connected to a relay doesn't affect the calculation of relay hours.

Azure Relay can handle multiple concurrent connections, enabling load balancing across multiple on-premises services. This means that if you have multiple services that need to communicate with each other, Azure Relay can help distribute the traffic and ensure that each service gets the resources it needs.

Relay can scale up based on demand, ensuring that hybrid applications can handle high levels of traffic without sacrificing performance.

Here's a summary of the benefits of load balancing and scaling with Azure Relay:

Migrating a namespace to another Azure subscription can be done using the Azure portal or PowerShell commands.

The namespace must already be active to be migrated, and the user running the commands must be an Administrator on both the source and target subscriptions.

To use the Azure portal, you can follow the steps outlined in Move resources to a new resource group or subscription.

The user running PowerShell commands must also be an Administrator on both subscriptions, and the namespace must be active.

Integrating On-Premises APIs with Cloud Applications is a breeze with Azure Relay. This feature allows cloud applications to connect to HTTP-based APIs hosted on-premises, enabling seamless integration without exposing APIs to the internet.

To get started, you'll need to configure the Hybrid Connection feature, which involves setting up a shared access policy in the Azure portal. This includes creating a shared access policy, generating a primary or secondary key, and assigning a name to the policy.

Here are the key properties you'll need to set for authentication and listening:

Once you've set these properties, you can connect to the Azure Relay service by setting the Listening property to True. This will establish a WebSocket connection to the address returned by the Hybrid Connection endpoint.

By using Azure Relay, you can integrate your on-premises APIs with cloud applications securely and easily, without exposing them to the internet. This is a game-changer for companies that want to expose their on-premises APIs to Azure applications.

Troubleshooting can be a challenge, but it's a crucial step in resolving issues with your Azure Relay.

If you're encountering problems, check out the Relay exceptions page for a list of common exceptions and suggested actions to take.

Don't let errors hold you back - knowing how to troubleshoot can save you time and frustration.

For a detailed description of common exceptions, see the Relay exceptions page.

Azure Relay offers robust security and authentication features to ensure safe data exchange between cloud and on-premises resources. This is achieved through encrypted relay sessions and token-based authentication using Azure Active Directory (AAD) and Shared Access Signatures (SAS).

To authenticate the listener component, you'll need to set four properties: AccessKey, AccessKeyName, HybridConnection, and NamespaceAddress. These properties are required to connect to the Azure Relay service.

The AccessKey and AccessKeyName are used to authenticate the listener with Azure Relay, and they can be obtained from the Azure portal. The HybridConnection property refers to the name of the hybrid connection created in the Azure portal, while the NamespaceAddress property is the fully qualified domain name of the relay namespace hosting the Hybrid Connection.

After setting these properties, you can set the Listening property to True to connect to the Azure Relay service. The component will attempt to connect to the service by making a listening request to the Hybrid Connection endpoint and establishing a WebSocket connection to the address returned.

To authenticate the sender component, the same four properties are required: AccessKey, AccessKeyName, HybridConnection, and NamespaceAddress. If the hybrid connection is configured to accept anonymous sends, AccessKey and AccessKeyName are not required.

Here are the properties required for authentication:

By using these properties and configuring the Azure Relay service correctly, you can ensure secure communication between cloud and on-premises resources.

The sender and receiver roles in Azure Relay are two distinct entities that interact with the service in different ways. The sender has two interactions with the service: it connects a Web Socket or it sends requests via HTTPS.

Requests can't be sent over a Web Socket from the sender role, so it's essential to understand the limitations of each interaction method. This is crucial for designing a reliable and efficient communication system.

The AzureRelayReceiver component is an easy way to implement the listener role in the Azure Relay service. It establishes a WebSocket connection with the service, specifically to an Azure Hybrid Connection endpoint in a registered namespace.

Once clients have requested connections and been accepted, data can be directly transferred between the connected client and AzureRelayReceiver. This enables seamless communication between the sender and receiver.

The AzureRelaySender component implements the sender role in the Azure Relay interaction model. It acts as the client which will initiate a new connection towards a listener client via the Azure Relay service.

The component establishes a WebSocket connection with the service, specifically to an Azure Hybrid Connection endpoint in a registered namespace. This connection allows the sender to send and receive data which will be relayed to and from the listener.

The Timeout value controls the amount of time the component will spend performing any operation before an exception is thrown. A value of 0 indicates that operations should run uninterrupted until completion or error.

Data can be received using the ConnectionDataIn event, which includes the ConnectionId of the client which sent the data, the Text of the message, and the DataFormat. The EOM parameter indicates whether or not this is the End Of Message.

The AzureRelayProxy component is designed to listen locally and forward received data over a connection to the Azure Relay Service, allowing any TCP-based client to connect and send data to Azure Relay Service without any additional knowledge.

This component creates a corresponding connection to the configured NamespaceAddress for each new connection made to AzureRelayProxy.

To authenticate the proxy before setting Listening, the same four properties required for the AzureRelayReceiver component are needed.

You can use SSL for incoming connections by setting SSLCert to a valid certificate with private key and setting SSLEnabled to True before setting Listening.

To stop listening for new connections, simply set Listening to False.

The component also supports forwarding traffic to another location, defined by the ForwardingHost and ForwardingPort properties, which must be specified for traffic to be forwarded.

Data will then flow freely between the connected client and the host once a connection is made and the forwarding properties are set.

Each new connection made to AzureRelayProxy results in a new connection made to the Azure Relay Service, and connections are not shared between clients.

To shutdown the server including existing connections, call Shutdown.

Create a Relay Namespace in the Azure Portal to serve as a container for all Relay resources. This is the first step in setting up Azure Relay.

To choose the right relay type, select either Hybrid Connections for HTTP/WebSocket or WCF Relay for TCP and HTTP protocols. This decision depends on your application's needs.

Configure Shared Access Policies with specific permissions for the on-premises and cloud applications. You can use Azure AD and SAS tokens for authentication.

For Hybrid Connections, download and install the Relay Hybrid Connection Manager (HCM) on your on-premises server. This creates a secure outbound connection from the server to Azure Relay.

Configure your cloud application to use the Hybrid Connection or WCF Relay endpoint. You can use the Azure SDKs or REST API to set up connections and begin relaying traffic.

Here's a quick checklist to get started:

With these steps complete, you'll be ready to monitor and scale your Azure Relay resources using Azure Monitor.

Azure Relay is a powerful tool for businesses looking to extend their on-premises applications to the cloud securely and reliably. It offers a range of key features and benefits that make it a preferred choice for hybrid connectivity in cloud environments.

One of the key features of Azure Relay is its ability to eliminate the need for open inbound firewall ports, reducing potential security vulnerabilities. This is achieved through outbound-only connections that are encrypted.

Azure Relay also simplifies connectivity between cloud applications and on-premises resources, streamlining hybrid architecture without complex VPN or network setups. This makes it easier to integrate cloud and on-premises systems.

Here are some of the key benefits of using Azure Relay:

Overall, Azure Relay is a powerful tool for businesses looking to extend their on-premises applications to the cloud securely and reliably.