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Service Principals vs Managed Identities

🔄 Service Principal vs. Managed Identity — Comparison Table

Feature Service Principal Managed Identity
Definition Identity used by applications or services to authenticate with Azure resources. Identity automatically managed by Azure for authenticating Azure resources to other services.
Creation Manually created via Azure CLI, PowerShell, or Portal. System-assigned: auto-created. User-assigned: manually created, reusable across resources.
Lifecycle Exists independently and must be manually maintained. System-assigned: tied to resource lifecycle. User-assigned: independent of resource lifecycle.
Credential Management Requires manual handling of secrets or certificates. Credentials and key rotation handled entirely by Azure.
Scope Can span across multiple subscriptions, tenants, and resources. System-assigned: specific to a single resource. User-assigned: sharable across multiple resources.
Permissions Must assign roles manually using RBAC. Roles also assigned using RBAC, but no need to handle credentials.
Use Case Suitable for external apps, CI/CD tools, or multi-tenant apps. Ideal for Azure-native workloads like VMs, Functions, and App Services accessing Azure services.
Security Prone to mismanagement if credentials are exposed or not rotated. More secure — no secret exposure and built-in credential rotation by Azure.

🔄 Azure to AWS Identity Mapping

Azure Concept AWS Equivalent
Service Principal IAM User or IAM Role with static credentials
Managed Identity (System-assigned) IAM Role attached to an EC2 instance (Instance Profile)
Managed Identity (User-assigned) Reusable IAM Role attached to multiple services
Azure RBAC Role Assignment IAM Policy Attachment
Azure Key Vault Access via MSI S3 / Secrets Manager access via IAM Role
Token from Azure AD Temporary security token from AWS STS