template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Metadata:
  AWS::ServerlessRepo::Application:
    Name: eks-auto-drain
    Description: Drains an EKS Worker Node when invoked by a CloudWatch event matching an Auto Scaling Group instance-terminating lifecycle action
    Author: Derek Keightley
    SpdxLicenseId: MIT
    LicenseUrl: LICENSE
    ReadmeUrl: README.md
    Labels: ['eks', 'asg', 'lambda', 'kubernetes']
    HomePageUrl: https://github.com/dkeightley/eks-auto-drain
    SemanticVersion: 0.1.0
    SourceCodeUrl: https://github.com/dkeightley/eks-auto-drain

Resources:
  LambdaFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      Handler: lambda_function.lambda_handler
      Runtime: python3.6
      Timeout: 600
      Policies:
        - Version: '2012-10-17'
          Statement:
            - Effect: Allow
              Action:
                - 'ec2:DescribeInstances'
                - 'eks:DescribeCluster'
                - 'autoscaling:CompleteLifecycleAction'
              Resource: '*'

  EventRule:
    Type: AWS::Events::Rule
    Properties:
      Description: eks-auto-drain event rule
      EventPattern: 
        source:
          - "aws.autoscaling"
        detail-type:
          - "EC2 Instance-terminate Lifecycle Action"
      State: ENABLED
      Targets: 
        - 
          Arn:
            Fn::GetAtt:
              - "LambdaFunction"
              - "Arn"
          Id: 
            Ref: "LambdaFunction"

  EventRuleSpot:
    Type: AWS::Events::Rule
    Properties:
      Description: eks-auto-drain event rule for spot instances
      EventPattern: 
        source:
          - "aws.ec2"
        detail-type:
          - "EC2 Spot Instance Interruption Warning"
      State: ENABLED
      Targets: 
        - 
          Arn:
            Fn::GetAtt:
              - "LambdaFunction"
              - "Arn"
          Id: 
            Ref: "LambdaFunction"

  PermissionForEventsToInvokeLambda: 
    Type: AWS::Lambda::Permission
    Properties: 
      FunctionName: 
        Ref: "LambdaFunction"
      Action: "lambda:InvokeFunction"
      Principal: "events.amazonaws.com"
      # SourceArn: 
      #   Fn::GetAtt: 
      #     - "EventRule"
      #     - "Arn"

Outputs:
  LambdaRole:
    Value: 
      Fn::GetAtt: 
        - "LambdaFunctionRole"
        - "Arn"
    Description: "Lambda IAM Role, to be added to the aws-auth ConfigMap"