Show HN: Pglayers – PostgreSQL extensions as stackable Docker layers

- Pglayers is a new tool that lets you build PostgreSQL extensions as reusable Docker image layers, so you can mix and match extensions without rebuilding from scratch each time. - PostgreSQL extensions add features (e.g., PostGIS for geospatial data, pgvector for AI embeddings) but traditionally require compiling and installing them into a specific database version — a tedious process that makes it hard to share or combine extensions. - Docker layers are incremental filesystem snapshots; by packaging each extension as its own layer, pglayers allows users to stack them like LEGO blocks on top of a base PostgreSQL image, saving time and simplifying deployment. - The project targets developers and DBAs who self-host PostgreSQL or run it in containerized environments (Kubernetes, Docker Compose) and need a clean, repeatable way to manage custom extensions without maintaining bulky custom images.