sam.md

Cheatsheet: aws SAM (serverless application model)

How to ZIP your files for packaging and deploying

If you want to ZIP the packages yourself, you can do the following commands

Zip a single Lambda function folder

zip -j your_lambda_code.zip your_lambda_code/*

Zip all Lambda functions in a folder (code/ in example)

for i in $(find code/* -type d -d 0); do zip -jr "${i%/}.zip" "$i"; done

Packaging and deploying

Package the template and files to upload to s3 for deployment

sam package --profile *yourprofile* --region *yourregion* --template-file template.yaml --s3-bucket *yourbucket* --output-template packaged.yaml

deploy with cloudformation

sam deploy --profile yourprofile --template-file packaged.yaml --region yourregion --capabilities CAPABILITY_IAM --stack-name name_of_your_stack

Build the application

With the -u command the functions will be build with a docker similar to the AWS

sam build -u

Now we can also invoke the functions locally

Local invoke

Create event payload

sam local generate-event sqs receive-message > SqsEvent.json

Invoke function

sam local invoke SubmitVerdictFunction -e SqsEvent.json

Start local API

sam local start-api

SAM layers

Make a layer for SAM to deploy

The folder structure needs to look like this

.
└── yourlayer/
    └── python/
        └── script_to_import.py

In the SAM template: Reference the FOLDER, not the zip Define the layer in your SAM template

 MyLayer:
    Type: AWS::Serverless::LayerVersion
    Properties:
        LayerName: layerExample
        Description: Layer to do cool stuff
        ContentUri: my_layer_folder/
        CompatibleRuntimes:
            - python3.6
            - python2.7
        LicenseInfo: MIT
        RetentionPolicy: retain

This can be referenced in a function with (YAML style) in your Function:

Layers:
    - !Ref layerExample

If the layer needs to be packaged and uploaded seperately

Put it in a ZIP file, while in the layer/ folder with the python sub directory

zip -r myname_layer.zip ./python/

Custom policies

Add a custom policy to a Function, example with SSM

Policies:
  - Statement:
    - Sid: SSMDescribeParametersPolicy
      Effect: Allow
      Action:
      - ssm:DescribeParameters
      Resource: '*'
    - Sid: SSMGetParameterPolicy
      Effect: Allow
      Action:
      - ssm:GetParameters
      - ssm:GetParameter
      Resource: '*'