📋 Amazon Cognito Cheat Sheet

Cognito essentials for the DVA-C02 exam — User Pools, Identity Pools, OAuth flows, MFA, and triggers.

User Pools

  • User Pool = user directory for sign-up and sign-in. Issues JWT tokens (ID, access, refresh).
  • Supports username/password, email, phone, social identity providers (Google, Facebook, Apple), SAML, OIDC.
  • MFA: SMS or TOTP. Can be required, optional, or off.
  • Hosted UI provides a pre-built sign-in/sign-up page with OAuth 2.0 / OIDC support.
  • Custom attributes: up to 50 per User Pool. Cannot be removed after creation.

Identity Pools

  • Identity Pool = federated identities. Exchanges tokens for temporary AWS credentials via STS.
  • Supports Cognito User Pool tokens, social providers, SAML, OpenID Connect, and custom developers.
  • Authenticated and unauthenticated (guest) roles can be configured.
  • Attribute-based access control (ABAC): map claims to session tags for fine-grained IAM policies.

Lambda Triggers

  • Pre sign-up: validate, auto-confirm, or auto-verify users before registration.
  • Pre authentication: add custom validation before sign-in.
  • Post confirmation: send welcome emails, log events after sign-up confirmation.
  • Pre token generation: add, suppress, or modify claims in the JWT before it is issued.
  • Custom message: customize verification/MFA messages and email subjects.
  • Migrate user: import users from a legacy system on first sign-in.

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