This document introduces Apache Sentry, an open source authorization module for Hadoop. It provides fine-grained, role-based authorization across Hadoop components like Hive, Impala and Solr. Sentry uses a centralized policy store to manage permissions for resources like databases, tables and collections. It evaluates rules to determine if a user's group has privileges to access resources based on their roles defined in the Sentry policy. Future work aims to introduce Sentry to more Hadoop components and provide a centralized authorization service for all protected resources and metadata.