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 Managing Lambda dependencies with 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.

To ensure that your layer content works properly in a Linux environment, we recommend creating your layer content using a tool like Docker or AWS Cloud9. AWS 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 AWS 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 the PATH variable picks up your layer content, your layer .zip file should have its dependencies in the following folder paths:

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

Node.js

Example file structure for the AWS X-Ray SDK for Node.js

xray-sdk.zip
└ nodejs/node_modules/aws-xray-sdk

Python

Example file structure for the Requests library

layer_content.zip
└ python
    └ lib
        └ python3.11
            └ site-packages
                └ requests
                └ <other_dependencies> (i.e. dependencies of the requests package)
                └ ...

Ruby

Example file structure for the JSON gem

json.zip
└ ruby/gems/3.3.0/
               | build_info
               | cache
               | doc
               | extensions
               | gems
               | └ json-2.1.0
               └ specifications
                 └ json-2.1.0.gemspec

Java

Example file structure for the Jackson JAR file

layer_content.zip
└ java
    └ lib
        └ jackson-core-2.17.0.jar
        └ <other potential dependencies>
        └ ...

All

Example file structure for the jq library

jq.zip
└ bin/jq

For language-specific instructions on packaging, creating, and adding a layer, refer to the following pages:

We recommend against using layers for the following languages. The linked pages contain more information.