Lambda Layers and Environment Variables

As your serverless applications grow, you need strategies for sharing code across functions and externalising configuration. Lambda Layers let you package shared libraries, custom runtimes, and common utilities separately from your function code. Environment variables provide a mechanism for injecting configuration without modifying code.

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What Are Lambda Layers?

A Lambda Layer is a ZIP archive containing libraries, a custom runtime, or other dependencies. Layers are extracted to the /opt directory in the execution environment and are available to your function code at runtime.

Execution Environment
+------------------------------------------+
|  /opt/                                   |
|  ├── nodejs/node_modules/  (Layer 1)     |
|  ├── python/lib/           (Layer 2)     |
|  └── custom-bin/           (Layer 3)     |
|                                          |
|  /var/task/                              |
|  └── index.mjs             (Your code)  |
+------------------------------------------+

Why Use Layers?