Setting up cross-account access between AWS Lambda and S3 is a common requirement in enterprise environments where resources are distributed across multiple AWS accounts for security, compliance, or organizational reasons. This guide provides a comprehensive walkthrough of establishing secure cross-account access, covering IAM role configuration, bucket policies, and practical implementation patterns.

Cross-account access enables Lambda functions in one AWS account (Account A) to securely access S3 buckets in another account (Account B). This pattern is essential for data processing workflows, backup operations, and multi-account architectures where centralized data storage serves multiple application accounts.

Data lake architectures represent a fundamental departure from traditional data warehousing approaches, embracing schema-on-read principles and polyglot storage strategies that accommodate the velocity, variety, and volume characteristics of modern data ecosystems. Unlike data warehouses that require upfront schema definition and ETL processes to conform data to predefined structures, data lakes preserve raw data in its native format while providing flexible analysis capabilities that adapt to evolving analytical requirements. AWS provides a comprehensive suite of services that enable sophisticated data lake implementations while managing the operational complexity traditionally associated with big data platforms.