Azure Traffic Manager
Azure Traffic Manager is a DNS-based traffic load balancer that allows you to distribute traffic optimally to your services hosted in different Azure regions, or even to external endpoints. It provides high availability and responsiveness by directing user traffic to the endpoint that provides the best performance or availability for your application.
How Traffic Manager Works
Traffic Manager uses the Domain Name System (DNS) to direct client requests to the most appropriate endpoint. You configure a Traffic Manager profile with a set of endpoints and a traffic-routing method. When a client makes a DNS query for your Traffic Manager domain name, Traffic Manager responds with the DNS record for the selected endpoint based on the chosen routing method and the health of the endpoints.
Traffic-Routing Methods
Traffic Manager supports several traffic-routing methods:
- Priority: Directs all traffic to a primary endpoint, and only fails over to secondary endpoints if the primary is unavailable.
- Weighted: Distributes traffic across a set of endpoints based on configured weights. This is useful for A/B testing or gradual rollouts.
- Performance: Directs traffic to the endpoint with the lowest network latency for the client. This is ideal for improving application responsiveness.
- Geographic: Directs traffic to the endpoint located closest to the user based on their geographic location.
- Multivalue: Returns multiple healthy endpoint IP addresses for a given DNS query. Clients then choose an endpoint from the returned list.
- Subnet: Directs traffic to specific endpoints based on the client's IP address subnet.
Key Features
- High Availability: Ensures your applications remain available by automatically failing over to healthy endpoints.
- Performance Optimization: Improves application responsiveness by routing users to the closest or best-performing endpoint.
- Geographic Distribution: Distribute your application across multiple regions for resilience and to serve global audiences.
- Endpoint Monitoring: Continuously monitors the health of your endpoints and takes them out of rotation if they become unhealthy.
- Flexible Routing: Supports various routing methods to meet diverse application requirements.
Creating a Traffic Manager Profile
You can create and manage Traffic Manager profiles using the Azure portal, Azure CLI, or PowerShell.
Here's a general overview of the steps:
- Navigate to the Azure portal.
- Search for "Traffic Manager profiles" and select it.
- Click "Create".
- Provide a name for the profile, select the subscription and resource group.
- Choose the desired Traffic-routing method.
- Configure the endpoints by adding their IP addresses or FQDNs (Fully Qualified Domain Names).
- Define the monitoring settings (protocol, port, interval, etc.).
- Review and create the profile.
Monitoring Endpoints
Traffic Manager performs health checks on your endpoints. You can configure:
- Protocol: HTTP, HTTPS, or TCP.
- Port: The port to use for the health check.
- Path: For HTTP/HTTPS, the path to probe on the endpoint (e.g.,
/health). - Interval: The frequency of probes.
- Timeout: How long to wait for a response.
- Tolerated number of failures: How many consecutive failures before an endpoint is considered unhealthy.
Example Scenario: Performance Routing
Imagine you have your web application deployed in both the East US and West Europe Azure regions. To ensure the best performance for your users worldwide:
- Create a Traffic Manager profile.
- Select the Performance routing method.
- Add your web application endpoint in East US and your web application endpoint in West Europe.
- Configure health probes.
Now, users in North America will be routed to the East US endpoint, and users in Europe will be routed to the West Europe endpoint, providing them with the lowest latency.
Considerations
- Traffic Manager operates at the DNS level. Changes to endpoint health may take time to propagate through DNS caches.
- It is essential to have at least two healthy endpoints for failover to work effectively.
- Ensure your application endpoints are correctly configured to respond to health probes.
For detailed configuration and advanced scenarios, please refer to the official Azure Traffic Manager documentation.