How to run lambda integration mode in serverless locally

[karthikpower]

I want to run serverless application locally earlier this was working using lambda proxy but I want to change it to lambda integration. So I have defined request and response template as follows but when I invoke lambda locally, I see this response,

    {
    "isBase64Encoded": false,
    "statusCode": 200,
    "headers": {
        "access-control-allow-origin": "*",
        "content-type": "application/json; charset=utf-8",
        "content-length": "2",
        "etag": "W/\"2-l9Fw4VUO7kr8CvBlt4zaMCqXZ0w\""
    },
    body
: 
"{\"error\":\"[{\\\"error\\\":\\\"Invalid query parameters\\\",\\\"messages\\\":[\\\"'page' is required\\\",\\\"'pagesize' is required\\\"]}]\"}"
}

and I expect only body in response this breaks running UI locally , when I run the application in aws I get correct response. Is there any additional configuration to be done in serverless.yml. This is how serverless.yml looks like

service: my-service-api

provider:
  name: aws
  runtime: nodejs16.x
  memorySize: 256 
  timeout: 10 
  region: us-west-2
  profile: xyz
  versionFunctions: false
  endpointType: regional
  deploymentBucket:
    name: ps-serverless
  vpc: xyz
  apiGateway:
    restApiId: xyz
    restApiRootResourceId: xyz
    restApiResources:
      /district-settings: xyz
plugins:
  - serverless-offline

custom:
  corsOptions:
    origin: http://localhost:3000/
    headers:
      - Content-Type
      - X-Amz-Date
      - Authorization
      - X-Api-Key
      - X-Amz-Security-Token
      - X-Amz-User-Agent
      - X-Xsrf-Token
    allowCredentials: true
  requestTemplate:
    application/json: |
      #set($request_header = $input.params().header)
      #set($request_query = $input.params().querystring) 
      #set($request_path = $input.params().path)
      #set($request_stage_vars = $stageVariables)
      #set($request_context = $context) 
      {  
        "body": "$util.escapeJavaScript($input.json('$'))",
        "httpMethod": "$context.httpMethod",
        "headers": {
        #foreach($header in $request_header.keySet())
              "$header" : "$util.escapeJavaScript($request_header.get($header))"
              #if($foreach.hasNext),#end
              #end
            }, 

        "queryStringParameters": {
        #foreach($query in $request_query.keySet())
              "$query" : "$util.urlDecode($request_query.get($query))"
              #if($foreach.hasNext),#end
              #end
            }, 

        "pathParameters": {
        #foreach($path in $request_path.keySet())
              "$path" : "$util.escapeJavaScript($request_path.get($path))"
              #if($foreach.hasNext),#end
              #end
            }, 

        "stageVariables": {
        #foreach($stage in $request_stage_vars.keySet())
              "$stage" : "$util.escapeJavaScript($request_stage_vars.get($stage))"
              #if($foreach.hasNext),#end
              #end
            }, 
        "resource": "$context.resourcePath",
        "path":"$context.path",
        "requestContext": {
        #foreach($reqContext in $request_context.keySet())
              "$reqContext" : "$util.escapeJavaScript($request_context.get($reqContext))"
              #if($foreach.hasNext),#end
              #end
            },
        "isBase64Encoded": false
      }

  responseHeaders:
    headers:
      Content-Type: ${env:CONTENT_TYPE}
      Access-Control-Allow-Credentials: ${env:ALLOW_CREDENTIAL}
      Strict-Transport-Security: ${env:SECURE_TRANSPORT_SECURITY}
      Cache-Control: ${env:CACHE_CONTROL}
      Content-Security-Policy: ${env:DEFAULT_CSP}
      X-Content-Type-Options: ${env:CONTENT_TYPE_OPTIONS}
      X-XSS-Protection: ${env:XSS_PROTECTION}
      X-Frame-Options: ${env:X_FRAME_OPTIONS}
      Pragma: ${env:PRAGMA}

    statusCodes:
      200:
        pattern: ''
        template:
          application/json: |
            #set($body = $input.json('$.body'))
            #set($statusCode = $input.json('$.statusCode'))
            #set($Integer = 0)
            $util.parseJson($body)
            #set($origin = $input.params().header)
            #set($context.responseOverride.header.Access-Control-Allow-Origin = $origin)
            #if($body.contains("error"))
            #set($context.responseOverride.status = $Integer.parseInt($statusCode))
            #end

functions:
  listDistricts:
    handler: src/districts/district-handler.list
    events:
      - http:
          path: 'district'
          method: get
          cors: ${self:custom.corsOptions}
          integration: lambda
          request:
            passThrough: NEVER
            template: ${self:custom.requestTemplate}
          response: ${self:custom.responseHeaders}

Any additional configuration I need to configure to get correct only body in response running locally will be of great help. Also I have GET request with query params that is not passed.

Please note I am using [email protected], node version 16. I am running app locally using sls offline start.

this is the lambda code

async (req: Request, res: Response, next: NextFunction): Promise<void> => {
 try {
      const districtListQueryParam: DistrictListQueryParam = (req.query as unknown) as DistrictListQueryParam;
      
      const districtList = <<some district service>>
      res.status(HttpStatusCodes.OK).send(districtList);
    } catch (err) {
      logger.error(`Error while listing the districts ${err.message}`);
      next(err);
    }
}

This is the error message in terminal from catch ,

{"filename":"http-error-middleware.js","level":"error","message":"Error: [{\"error\":\"Invalid query parameters\",\"messages\":[\"'page' is required\". ....

[karthikpower]

[offline] _____ REQUEST TEMPLATE PROCESSING _____
[offline] Velocity rendered: {
"body": "{}",
"httpMethod": "GET",
"headers": {
"Host" : "localhost:3000"
, "Connection" : "keep-alive"
, "sec-ch-ua" : ""Not/A)Brand";v="99", "Google Chrome";v="115", "Chromium";v="115""
, "Accept" : "application/json, text/plain, /"
, "sec-ch-ua-mobile" : "?0"
, "User-Agent" : "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36"
, "sec-ch-ua-platform" : ""macOS""
, "Origin" : "http://localhost:8000"
, "Sec-Fetch-Site" : "same-site"
, "Sec-Fetch-Mode" : "cors"
, "Sec-Fetch-Dest" : "empty"
, "Referer" : "http://localhost:8000/"
, "Accept-Encoding" : "gzip, deflate, br"
, "Accept-Language" : "en-GB,en-US;q=0.9,en;q=0.8"
},

"queryStringParameters": {
"page" : '1'
, "pagesize" : '12'
},
....

[offline] event: {}

This is what I see in terminal : though request template is processed but event is printed as empty. Though I have serverless-offline plugin