Query COGs with Lambda

TL;DR
Use Lambda with rasterio (and/or rio-tiler) to read Cloud Optimized GeoTIFFs (COGs) in S3 via HTTP range requests and return clipped/warped subsets or tiles on demand.

Flow: Client → API Gateway → Lambda → S3 (COG) → Lambda returns PNG/WEBP/JSON.
Cache headers (or API Gateway/Lambda@Edge/CloudFront in front) can reduce repeated reads.

Overview

This pattern serves on-demand reads from large rasters stored as COGs in S3. A client requests a window/tile/stat; API Gateway invokes Lambda, which uses rasterio (or rio-tiler) to read only the needed byte ranges from the COG and returns the result (PNG/WEBP/COG tile, or JSON stats).

When to Use

• You need dynamic subsets (windows, tiles, reprojected extracts) without pre-generating tiles.
• You want to access pixel data, without tiling for visualisation
• Pay-per-use access to large rasters; low/irregular traffic.
• You want to keep data in S3 and avoid maintaining tile servers.

Trade-offs

• Cold starts and Lambda timeout/memory limits for heavy reads.
• Throughput/concurrency can be constrained for very hot workloads.
• Per-request CPU is limited; heavy reprojection/warps can be slow.
• Requires creation of a Docker image Lambda for rasterio and GDAL support.

References

• Blog post: https://www.addresscloud.com/blog/serverless-flood
• Example code (archived): https://github.com/addresscloud/aws-lambda-docker-rasterio

For Tiling from COGs check out TiTiler (note: this should probably be it's own pattern).