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. Creating a layer involves three general steps:
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Package your layer content. This means creating a .zip file archive that contains the dependencies you want to use in your functions.
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Create the layer in Lambda.
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Add the layer to your functions.
We don't recommend using layers to manage dependencies for Lambda functions written in Go. This is because Lambda functions in Go compile into a single executable, which you provide to Lambda when you deploy your function. This executable contains your compiled function code, along with all of its dependencies. Using layers not only complicates this process, but also leads to increased cold start times because your functions need to manually load extra assemblies into memory during the init phase.
To use external dependencies with your Go handlers, include them directly in your deployment package. By doing so, you simplify the deployment process and also take advantage of built-in Go compiler optimizations. For an example of how to import and use a dependency like the AWS SDK for Go in your function, see Define Lambda function handlers in Go.
