AWS OpenSearch Cluster with Serverless Framework

readme.md

Source code from "Deploying an AWS OpenSearch Cluster with Serverless Framework".

handler.js

const aws4 = require('aws4')

const host = process.env.OPENSEARCH_ENDPOINT

module.exports.default = async function handler(
  event,
  context,
) {
  const fetch = (await import('node-fetch')).default
  const indexName = 'example'

  const options = aws4.sign({
    host,
    path: '/' + indexName,
    method: 'HEAD',
    headers: { 'Content-Type': 'application/json' },
  })

  const result = await fetch(
    `https://${host}/${indexName}`,
    options,
  )
  
  if (result.status === 404) {
    return {
      statusCode: 404,
      body: JSON.stringify({ message: `Index "${indexName}" does not exist.`})
    }
  }
  
  const body = await result.text()
  
  return { statusCode: 200, body }
}

serverless.yml

service: opensearch-howto

provider:
  name: aws
  runtime: nodejs14.x

functions:
  example:
    description: An OpenSearch example
    handler: handler.default
    memorySize: 256
    events:
      - http: GET /example
    environment:
      OPENSEARCH_ENDPOINT: !GetAtt OpenSearchDomain.DomainEndpoint
    role: LambdaOpenSearchAccessRole

resources:
  Resources:
    LambdaOpenSearchAccessRole:
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument:
          Statement:
            - Effect: Allow
              Principal:
                Service: lambda.amazonaws.com
              Action: sts:AssumeRole
        ManagedPolicyArns:
          - arn:aws:iam::aws:policy/AWSXrayWriteOnlyAccess
          - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
  #       Policies:
  #         - PolicyName: ssm
  #           PolicyDocument:
  #             Statement:
  #               - Effect: Allow
  #                 Action:
  #                   - ssm:GetParametersByPath
  #                 Resource:
  #                   - arn:aws:ssm:*:*:parameter/${self:service}/*  
  
    # Documentation: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-opensearchservice-domain.html
    OpenSearchDomain:
      Type: AWS::OpenSearchService::Domain
      Properties:
        DomainName: 'example'
        EngineVersion: 'OpenSearch_1.0'
        ClusterConfig:
          # DedicatedMasterEnabled: true
          InstanceCount: '1'
          # ZoneAwarenessEnabled: true
          InstanceType: 't3.small.search'
          # DedicatedMasterType: 't3.small.search'
          # DedicatedMasterCount: '1'
        EBSOptions:
          EBSEnabled: true
          VolumeSize: '20'
          VolumeType: 'gp2'
        AccessPolicies:
          Version: '2012-10-17'
          Statement:
            - Effect: 'Allow'
              Principal:
                AWS: !GetAtt LambdaOpenSearchAccessRole.Arn
              Action: 'es:ESHttp*'
              Resource:
                - !Sub 'arn:aws:es:${AWS::Region}:${AWS::AccountId}:domain/example/*' # "example" should be the same as your value for DomainName above
        AdvancedOptions:
          rest.action.multi.allow_explicit_index: true