Azure Authentication Patterns: Managed Identity vs Service Principal vs OIDC

Modern Azure applications require secure authentication without exposing secrets. In this article, I compare three common approaches used in real-world deployments.

1. Service Principal (Client Secret)

Traditional approach using client ID and secret.

• Easy to implement
• Requires secret storage
• Security risk if leaked

2. Managed Identity

Azure-managed identity assigned to a resource (VM, App Service, etc).

• No secrets required
• Best option for Azure-hosted apps
• Limited to Azure resources

3. OIDC Federation (GitHub Actions)

Modern approach using OpenID Connect without storing credentials.

• No secrets stored
• Short-lived tokens
• Ideal for CI/CD pipelines

Conclusion

For production systems, I prefer Managed Identity for Azure workloads and OIDC federation for CI/CD pipelines. Service principals should be used only when other options are not available.

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