Polaris Service Principals

Polaris Service Principals

Polaris Service Principals are the programmatic identities managed inside Apache Polaris. Because catalogs are accessed by machines (such as query engines, automated ETL scripts, and BI tools) rather than humans entering credentials on a web page, Polaris uses service principals to control API access. Each service principal represents a unique identity that can be authenticated and authorized.

Authentication Credentials

When a service principal is created, Polaris generates a client ID and a client secret:

• Client ID: A unique public identifier for the service principal.
• Client Secret: A secure cryptographic string that must be kept secret.

Query engines use this pair of values to authenticate via the standard OAuth2 token flow. Once authenticated, the engine receives a temporary token to run catalog API calls, such as loading tables or updating schemas.

Association with Roles

To prevent unauthorized access, a new service principal has no permissions by default. It must be explicitly mapped to a principal role:

Service Principal (e.g. Spark_Ingest_Principal)
     │
     └── Granted to ──> Principal Role (e.g. Ingestion_Writer_Role)

This mapping allows the service principal to inherit the catalog permissions assigned to the role, such as writing to specific tables or reading specific catalog namespaces.

Operational Best Practices

When managing programmatic identities, security teams follow several operational rules:

• Principle of Least Privilege: Create dedicated service principals for distinct workloads (e.g. one for Spark writes and one for Trino reads) rather than sharing a single administrative principal.
• Credential Rotation: Periodically regenerate client secrets using the Polaris management API or console to reduce the risk of compromise.
• Granular Auditing: Name service principals descriptively to ensure catalog logs clearly show which service made specific table updates.