API Gateways and Microservices Security

API gateways sit at the edge of a microservices stack. They act like a front door, deciding who can enter and how requests travel to backend services. When security is built into the gateway, teams can protect data, control traffic, and reduce risk across many services. This post shares practical ideas to strengthen API gateways and safeguard microservices without slowing delivery. The goal is simple: clear policies, verified identities, and trusted communication.

Key security needs include strong identity, trusted communication, and clear policies. Use TLS to encrypt traffic in transit and mTLS for service-to-service calls so every hop is authenticated. Validate tokens at the edge: JWTs or opaque tokens issued by a trusted identity provider, and check token lifetimes. Enforce scopes and roles, mapping them to API routes, so a user can access only what they should. Rotate keys regularly and plan for token revocation. Finally, combine alerting and logs to spot anomalies quickly and respond before problems grow.

  • Authenticate and authorize at the gateway with OAuth 2.0 / OpenID Connect.
  • Prefer mutual TLS between gateway and services to prevent eavesdropping.
  • Apply rate limits, quotas, and circuit breakers to protect the backend.
  • Centralize logging and auditing for accountability.
  • Protect APIs with WAF rules and input validation.

Example: A payment service uses the gateway to verify a JWT issued by an identity provider. The gateway checks expiry, issuer, and required scopes before routing to the payment microservice. Between the gateway and services, mTLS is enabled to protect metadata. If a token is revoked or expires, requests fail at the edge, not inside the system. This reduces risk and keeps payments fast while staying under strong control.

With these practices, teams keep a broad surface area safer while keeping momentum. Start small, implement the baseline security at the gateway, and extend as you add services.

Key Takeaways

  • Gateways centralize security for microservices.
  • Use strong identity, short-lived tokens, and mTLS where possible.
  • Combine rate limiting, logging, and WAF for resilience.