In large-scale cloud architectures, where APIs serve both internal consumers and external partners across multiple regions, a single-region API Management instance can quickly become a bottleneck.

To ensure high availability, low latency, geo-resilience, and security, this pattern showcases how to deploy Azure API Management (APIM) in a multi-region active/active setup, fronted by Azure Front Door for global distribution and Application Gateway with WAF for regional protection.

This design enables internal and external API consumption through secured channels while preserving governance, performance, and observability at scale.

You can choose this pattern if:

• You serve global consumers (external or internal) and need regional performance.
• You want to provide internal-only APIs without exposing them to the internet.
• You require zero trust access, combining public and private traffic isolation.
• Your API Management strategy must scale across multiple Azure regions.
• You want to enforce security using Web Application Firewalls (WAF).
• You need global high availability with minimal failover complexity.
• Your APIs must be exposed via a unified global entrypoint (e.g., api.cdl.com).
• You want centralized DevOps, monitoring, and observability across regions.

Architecture Overview

This pattern deploys Azure API Management in multi-region mode, using one primary instance (North Europe) and two secondary instances (East US 2 and Southeast Asia). These are all part of the same Global Shared APIM setup, offering unified configuration but localized performance.

Each region is protected by an Application Gateway with WAF enabled. These gateways sit behind Network Virtual Appliances (NVAs) and expose private IPs only, ensuring that the APIM backends are not directly reachable from the internet.

The public entrypoint (api.cdl.com) is managed by Azure Front Door, which routes requests to the nearest healthy Application Gateway based on geography and health probes.

Internal APIs (used by internal backend services) are accessible only within the internal network via private endpoints, ensuring no public exposure.

This setup provides a secure, distributed, and performant API infrastructure.

Components and Roles

Component	Role
Azure API Management	Global shared APIM with one primary instance (North Europe) and two secondary instances.
Azure Front Door	Global entrypoint that routes traffic based on proximity and health.
Application Gateway + WAF	Regional layer 7 load balancer protecting APIM instances from threats and attacks.
Network Virtual Appliance	Enforces outbound/inbound flow rules before reaching App Gateway.
Internal Backend Services	Hosted in VNETs, not reachable from the internet.

Security

Securing APIs at global scale is more than firewalls and tokens — it’s about defense-in-depth and controlling every layer of the stack: network, identity, and application.

In this pattern, security starts at the edge:

• Azure Front Door acts as the global reverse proxy, exposing a single DNS endpoint (api.cdl.com) with HTTPS enforced.
• Application Gateways with WAF enabled in each region inspect and block malicious traffic based on OWASP rules.
• Traffic then passes through Network Virtual Appliances (NVAs), adding another layer of filtering or logging (customizable).
• Only internal subnets are allowed to reach the private IPs of the APIM instances.
• Internal APIs are not exposed to Front Door at all; they’re accessed privately, inside the VNET.

Access to APIM management (Dev Portal, Publisher Portal) is centralized in the primary instance only, reducing the attack surface.

Availability

Multi-region deployment offers geo-redundancy by design. Front Door probes each region’s Application Gateway and routes traffic based on health and latency.

In this setup:

• If North Europe becomes unavailable, traffic from Europe is rerouted to East US or Southeast Asia.
• If a local App Gateway or APIM node is degraded, only that region is bypassed — not the whole service.
• Internal API access is still possible locally in each region, ensuring business continuity.

This model is particularly suited for mission-critical APIs where downtime in one region must not impact the global consumer experience.

Scalability

Scalability in this pattern is both horizontal and geo-distributed:

• API Management supports scale-out via regional instances — all managed centrally.
• Application Gateway scales automatically based on load.
• You can increase capacity in a single region or add new regions over time.
• Front Door handles scaling transparently and globally.
• DevOps can deploy APIs once (centrally) and replicate across all regions automatically.

This model supports growth by design: new consumers, new regions, and higher traffic can be added without architectural changes.

Network

Network design in multi-region API deployments can take many forms.

In this pattern, we focus on service endpoint–based communication, with the following setup:

• APIM instances are deployed inside VNETs in each region.
• These VNETs are protected by NVAs + Application Gateways, exposing only private IPs to APIM.
• Internal backends are not reachable from the internet — they use internal APIs over private connections.
• Azure Front Door reaches the App Gateway’s public IP, which then routes internally to APIM.

In some future scenarios, you may prefer to use Azure Private Link, ExpressRoute, or firewall + DNS + UDR-based flows for even deeper control. That’s a separate design pattern we’ll cover soon.

Observability

Global deployments require centralized and distributed observability. This pattern integrates:

• Azure Monitor and Log Analytics for infrastructure and network-level metrics.
• Azure Application Insights for APIM usage, failures, and latency tracking.
• Grafana dashboards (connected to Log Analytics) for real-time visualization across all regions.
• Health Probes in Azure Front Door to monitor gateway responsiveness and trigger failovers.
• WAF logs for attack detection and forensic analysis.

Together, these tools ensure complete visibility from edge to backend, and from consumer to API logic.