Packaging your layer content

A Lambda layer is a .zip file archive that contains supplementary code or data. Layers usually contain library dependencies, a custom runtime, or configuration files.

This section explains how to properly package your layer content. For more conceptual information about layers and why you might consider using them, see Working with Lambda layers.

The first step to creating a layer is to bundle all of your layer content into a .zip file archive. Because Lambda functions run on Amazon Linux, your layer content must be able to compile and build in a Linux environment. If you build packages on your local Windows or Mac machine, you’ll get output binaries for that operating system by default. These binaries may not work properly when you upload them to Lambda.

To ensure that your layer content works properly in a Linux environment, we recommend creating your layer content using Amazon Cloud9. Amazon Cloud9 is a cloud-based integrated development environment (IDE) that provides built-in access to a Linux server for running and testing code. For more information, see Using Lambda layers to simplify your development process on the Amazon Compute Blog.

Layer paths for each Lambda runtime

When you add a layer to a function, Lambda loads the layer content into the /opt directory of that execution environment. For each Lambda runtime, the PATH variable already includes specific folder paths within the /opt directory. To ensure that your layer content gets picked up by the PATH variable, include the content in the following folder paths:

The following examples show how you can structure the folders in your layer .zip archive.