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AzureInternal and partner APIs11 min read

Zero trust API access on Azure, end to end

An Azure pattern for exposing APIs to users and partners with no implicit trust. Entra ID for identity, conditional access for posture, APIM for policy, and private endpoints for everything behind the line.

Why zero trust on Azure is different

Azure rewards a clear edge. Front Door for global ingress, API Management as the policy layer, and a strict vnet boundary that everything sensitive lives inside. Public service endpoints are off by default.

The interesting design choice is not the controls, it is the identity model. Entra ID issues tokens for users and workloads alike. Conditional access decides whether a token can be minted in the first place, based on device, location, risk score, and group.

Reference pattern

Requests hit Front Door (WAF + DDoS), proxy to APIM in the home region. APIM enforces rate limits, JWT validation against Entra ID, request schema validation, and IP allowlisting for partner traffic.

APIM is integrated to a private vnet, so backends are not exposed. App Service, Functions, SQL, Storage, and Key Vault are all bound to private endpoints. Outbound DNS resolves to private IPs.

Identity and access

Users authenticate to Entra ID. Conditional access requires managed device, sign in risk low, and group membership matching the API. For privileged operations we use PIM with just in time elevation and approval.

  • workload identity federation for github actions (no secrets)
  • managed identities for app service and functions
  • customer managed keys in key vault, rotated quarterly
  • defender for cloud running posture + workload protection
  • private dns zones linked to vnet for endpoint resolution

Telemetry

Every layer ships to Log Analytics. We route a subset to Sentinel for detection and Cost Management for budget alerts. The hot path for detection is sign in logs, APIM gateway logs, and Defender alerts.

References

Official documentation and standards we draw on for this pattern.

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Takeaway

Zero trust on Azure is not a product, it is the combination of identity, network, and policy moving in step. Get the three to agree and the rest follows.

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