AWS Lambda Layers
If you are using AWS as a provider, all layers inside the service are AWS Lambda layers.
Configuration
All of the Lambda layers in your serverless service can be found in serverless.yml under the layers property.
# serverless.yml
service: myService
provider:
name: aws
layers:
hello:
path: layer-dir # required, path to layer contents on disk
name: ${sls:stage}-layerName # optional, Deployed Lambda layer name
description: Description of what the lambda layer does # optional, Description to publish to AWS
compatibleRuntimes: # optional, a list of runtimes this layer is compatible with
- python3.11
compatibleArchitectures: # optional, a list of architectures this layer is compatible with
- x86_64
- arm64
licenseInfo: GPLv3 # optional, a string specifying license information
# allowedAccounts: # optional, a list of AWS account IDs allowed to access this layer.
# - '*'
# note: uncommenting this will give all AWS users access to this layer unconditionally.
retain: false # optional, false by default. If true, layer versions are not deleted as new ones are created
You can add up to 5 layers as you want within this property.
# serverless.yml
service: myService
provider:
name: aws
layers:
layerOne:
path: layerOne
description: optional description for your layer
layerTwo:
path: layerTwo
layerThree:
path: layerThree
Your layers can either inherit their packaging settings from the global package property.
# serverless.yml
service: myService
provider:
name: aws
package:
patterns:
- '!layerSourceTarball.tar.gz'
layers:
layerOne:
path: layerOne
Or you can specify them at the layer level.
# serverless.yml
service: myService
provider:
name: aws
layers:
layerOne:
path: layerOne
package:
patterns:
- '!layerSourceTarball.tar.gz'
Keep in mind that all patterns (even when inherited from the service config) are resolved against the layer's path and not the service path.
You can also specify a prebuilt archive to create your layer. When you do this, you do not need to specify the path element of your layer.
# serverless.yml
service: myService
provider:
name: aws
layers:
layerOne:
package:
artifact: layerSource.zip
Permissions
You can make your layers usable by other accounts by setting the allowedAccounts property:
# serverless.yml
service: myService
provider:
name: aws
layers:
layerOne:
path: layerOne
allowedAccounts:
- 111111111111 # a specific account ID
- 222222222222 # a different specific account ID
Another example, making the layer publicly accessible:
# serverless.yml
service: myService
provider:
name: aws
layers:
layerOne:
path: layerOne
allowedAccounts:
- '*' # ALL accounts!
Using your layers
Using the layers configuration key in a function makes it possible for your layer with a function
functions:
hello:
handler: handler.hello
layers:
- arn:aws:lambda:region:XXXXXX:layer:LayerName:Y
To use a layer with a function in the same service, use a CloudFormation Ref. The name of your layer
in the CloudFormation template will be your layer name
TitleCased (without spaces) and have
LambdaLayer appended to the end. EG:
layers:
test:
path: layer
functions:
hello:
handler: handler.hello
layers:
- !Ref TestLambdaLayer
You can also configure layers at the service level. EG:
# serverless.yml
service: myService
provider:
name: aws
runtime: python3.11
layers:
- arn:aws:lambda:us-east-1:xxxxxxxxxxxxx:layer:xxxxx:mylayer1
- arn:aws:lambda:us-east-1:xxxxxxxxxxxxx:layer:xxxxx:mylayer2
functions:
hello1:
handler: handler.hello1
hello2:
handler: handler.hello2