Lambda layers allow sharing code and data across functions by packaging dependencies in a ZIP file. Layers can contain common code, libraries, or other components and can be referenced by up to five functions at once. The Lambda runtime API allows selecting a custom runtime using an executable bootstrap file to interface between code and the Lambda environment. Several open source runtimes have been developed using this API.

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Lambda Layers and Runtime API
Danilo Poccia
Principal Evangelist, Serverless
@danilop

2. © 2018, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Agenda
Lambda Layers
Lambda Runtime API
Demo

3. Lambda Layers

4. Photo by Thibault Mokuenko on Unsplash
A way to centrally manage code and data
that is shared across multiple functions

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Lambda Layers Use Cases
Custom code that is used by
multiple functions, Partner
libraries, etc.
Shared code that doesn’t change
frequently
Layers can be shared across
Accounts, publicly with any
Account and all Accounts within
an Organization
Lambda
Layers
Lambda
Function
Lambda
Function
Lambda
Layers
Account A Account B
Same-account Layers
Lambda
Layers
Icon made by Freepik from www.flaticon.com

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Using Lambda Layers
Put common components in a ZIP file
and upload it as a Lambda Layer
Layers are immutable and can be
versioned to manage updates
When a version is deleted or
permissions to use it are revoked,
functions that used it previously will
continue to work, but you won’t be
able to create new ones
Lambda
Layers
arn:aws:lambda:region:accountId:layer:shared-lib:1
Lambda
Layers
arn:aws:lambda:region:accountId:layer:shared-lib:2
Lambda
Layers
arn:aws:lambda:region:accountId:layer:shared-lib:3
Icon made by Freepik from www.flaticon.com

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Using Lambda Layers
You can reference up to five layers,
one of which can optionally be a
custom runtime
When the function is invoked, layers
are installed in the execution
environment in the order you
provided
The overall, uncompressed size of
function and layers is subject to the
usual unzipped deployment package
size limit (250MB)
Lambda
Layers
Lambda
Function
Lambda
Layers
Lambda
Layers
Lambda
Layers
Lambda
Layers
Up to 5 Layers
/opt NodeJS v11.X provided runtime
/opt Node runtime + node_modules

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Including Library Dependencies in a Layer
Runtime Folders
Node.js
nodejs/node_modules
nodejs/node8/node_modules (NODE_PATH)
Python
python
python/lib/python3.7/site-packages (site directories)
Java java/lib (CLASSPATH)
Ruby
ruby/gems/2.5.0 (GEM_PATH)
ruby/lib (RUBY_LIB)
All
bin (PATH)
lib (LD_LIBRARY_PATH)

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Lambda Layers API
New APIs
• ListLayers
• ListLayerVersions
• PublishLayerVersion
• DeleteLayerVersion
• GetLayerVersion
• GetLayerVersionPolicy
• AddLayerVersionPermission
• RemoveLayerVersionPermission
Updated
• CreateFunction
• UpdateFunctionConfiguration
docs.aws.amazon.com/lambda/latest/dg/API_Reference.html

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SAM support
BashRuntime:
Type: AWS::Serverless::LayerVersion
Properties:
LayerName: bash-sam
Description: Bash Runtime FWIW
ContentUri: bash_runtime
LicenseInfo: 'MIT-0 license’
RetentionPolicy: Retain
HelloBashFunction:
Type: AWS::Serverless::Function
Properties:
CodeUri: bash_hello
Handler: hello.handler
Runtime: provided
Layers:
- !Ref BashRuntime
- <LayerTwoArn>
New AWS::Serverless::LayerVersion
resource creates new Lambda Layer
from local filesystem or S3 URI
Layers can also be restricted to certain
Runtimes (CompatibleRuntimes
property)
SAM CLI 0.8.1+ supports Layers locally
and remotely (ARN)

11. Lambda Runtime API

12. Photo by Jeremy Lapak on Unsplash
A simple interface to use
any programming
language, or a specific
language version, for
developing your
functions

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Lambda Runtime API
Select a custom runtime in the console
(provided in the API/SDKs/CLI) as the
runtime of a Lambda function
The Function must include (in its code
or in a layer) an executable file
called bootstrap
The runtime bootstrap is responsible for
the communication between your code
and the Lambda environment
Bash FWIW
docs.aws.amazon.com/lambda/latest/dg/runtimes-walkthrough.html

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Runtime Boostrap
The bootstrap executable act as a bridge
between the Runtime HTTP API and the
Function to be executed
Bootstrap needs to manage response/error
handling, context creation and function
execution
Information on the interface endpoint and
the function handler are shared as
environment variables
/runtime API
/invocation/next
/init/error /ID/error
/invocation/ID/response
/invocation/ID/error
bootstrap
Process events/headers
Clean up
Initialize and Invoke function
Response/Error handling
Lambda
Function

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Lambda Runtime API - Environment Variables
• AWS_LAMBDA_RUNTIME_API
• HOSTNAME:PORT
• _HANDLER
• SCRIPT_NAME.FUNCTION_NAME
• LAMBDA_TASK_ROOT
• The directory that contains the function code

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Lambda Runtime API - Runtime Interactions
• POST /runtime/init/error
• GET /runtime/invocation/next
• The invocation-id is in the Lambda-Runtime-Aws-Request-Id header
• For AWS X-Ray there is a tracing header Lambda-Runtime-Trace-Id
• POST /runtime/invocation/{invocation-id}/response
• POST /runtime/invocation/{invocation-id}/error
• Sample Endpoint + Resource Path
• http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next
More info and OpenAPI specification available: docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html

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Open Source Runtimes already available
C++ (AWS)
Rust (AWS)
Nim (LambCI)
Erlang (Alert Logic)
Elixir (Alert Logic)
Cobol (Blu Age)
Node.js (NodeSource N|Solid)
PHP (Stackery)
github.com/mthenw/awesome-layers
Check this out for more links

18. Demo

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Lambda Layers Demo
• Node.js
• Creating a layer with moment.js, request, and request-promise
• Using the layer
• Python
• SciPy & NumPy layer example
• Adding a matplotlib layer

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Lambda Runtime API Demo
• Creating a Custom Runtime for… Bash functions!
• Bootstrap
• hello.sh

21. Photo by Christoph Krichenbauer on Unsplash
What are you going to build?

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Thank you!
@danilop