# Create AWS Lambda proxy integrations for HTTP APIs in API Gateway A Lambda proxy integration enables you to integrate an API route with a Lambda function. When a client calls your API, API Gateway sends the request to the Lambda function and returns the function's response to the client. For examples of creating an HTTP API, see [Create an HTTP API](http-api-develop.md#http-api-examples). ## Payload format version The payload format version specifies the format of the event that API Gateway sends to a Lambda integration, and how API Gateway interprets the response from Lambda. If you don't specify a payload format version, the AWS Management Console uses the latest version by default. If you create a Lambda integration by using the AWS CLI, CloudFormation, or an SDK, you must specify a `payloadFormatVersion`. The supported values are `1.0` and `2.0`. For more information about how to set the `payloadFormatVersion`, see [create-integration](https://docs.aws.amazon.com/cli/latest/reference/apigatewayv2/create-integration.html). For more information about how to determine the `payloadFormatVersion` of an existing integration, see [get-integration](https://docs.aws.amazon.com/cli/latest/reference/apigatewayv2/get-integration.html) ### Payload format differences The following list shows differences between the `1.0` and `2.0` payload format versions: + Format `2.0` doesn't have `multiValueHeaders` or `multiValueQueryStringParameters` fields. Duplicate headers are combined with commas and included in the `headers` field. Duplicate query strings are combined with commas and included in the `queryStringParameters` field. + Format `2.0` has `rawPath`. If you use an API mapping to connect your stage to a custom domain name, `rawPath` won't provide the API mapping value. Use format `1.0` and `path` to access the API mapping for your custom domain name. + Format `2.0` includes a new `cookies` field. All cookie headers in the request are combined with commas and added to the `cookies` field. In the response to the client, each cookie becomes a `set-cookie` header. ### Payload format structure The following examples show the structure of each payload format version. All headernames are lowercased. ------ #### [ 2.0 ] ``` { "version": "2.0", "routeKey": "$default", "rawPath": "/my/path", "rawQueryString": "parameter1=value1¶meter1=value2¶meter2=value", "cookies": [ "cookie1", "cookie2" ], "headers": { "header1": "value1", "header2": "value1,value2" }, "queryStringParameters": { "parameter1": "value1,value2", "parameter2": "value" }, "requestContext": { "accountId": "123456789012", "apiId": "api-id", "authentication": { "clientCert": { "clientCertPem": "CERT_CONTENT", "subjectDN": "www.example.com", "issuerDN": "Example issuer", "serialNumber": "a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1", "validity": { "notBefore": "May 28 12:30:02 2019 GMT", "notAfter": "Aug 5 09:36:04 2021 GMT" } } }, "authorizer": { "jwt": { "claims": { "claim1": "value1", "claim2": "value2" }, "scopes": [ "scope1", "scope2" ] } }, "domainName": "id.execute-api.us-east-1.amazonaws.com", "domainPrefix": "id", "http": { "method": "POST", "path": "/my/path", "protocol": "HTTP/1.1", "sourceIp": "192.0.2.1", "userAgent": "agent" }, "requestId": "id", "routeKey": "$default", "stage": "$default", "time": "12/Mar/2020:19:03:58 +0000", "timeEpoch": 1583348638390 }, "body": "Hello from Lambda", "pathParameters": { "parameter1": "value1" }, "isBase64Encoded": false, "stageVariables": { "stageVariable1": "value1", "stageVariable2": "value2" } } ``` ------ #### [ 1.0 ] ``` { "version": "1.0", "resource": "/my/path", "path": "/my/path", "httpMethod": "GET", "headers": { "header1": "value1", "header2": "value2" }, "multiValueHeaders": { "header1": [ "value1" ], "header2": [ "value1", "value2" ] }, "queryStringParameters": { "parameter1": "value1", "parameter2": "value" }, "multiValueQueryStringParameters": { "parameter1": [ "value1", "value2" ], "parameter2": [ "value" ] }, "requestContext": { "accountId": "123456789012", "apiId": "id", "authorizer": { "claims": null, "scopes": null }, "domainName": "id.execute-api.us-east-1.amazonaws.com", "domainPrefix": "id", "extendedRequestId": "request-id", "httpMethod": "GET", "identity": { "accessKey": null, "accountId": null, "caller": null, "cognitoAuthenticationProvider": null, "cognitoAuthenticationType": null, "cognitoIdentityId": null, "cognitoIdentityPoolId": null, "principalOrgId": null, "sourceIp": "192.0.2.1", "user": null, "userAgent": "user-agent", "userArn": null, "clientCert": { "clientCertPem": "CERT_CONTENT", "subjectDN": "www.example.com", "issuerDN": "Example issuer", "serialNumber": "a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1:a1", "validity": { "notBefore": "May 28 12:30:02 2019 GMT", "notAfter": "Aug 5 09:36:04 2021 GMT" } } }, "path": "/my/path", "protocol": "HTTP/1.1", "requestId": "id=", "requestTime": "04/Mar/2020:19:15:17 +0000", "requestTimeEpoch": 1583349317135, "resourceId": null, "resourcePath": "/my/path", "stage": "$default" }, "pathParameters": null, "stageVariables": null, "body": "Hello from Lambda!", "isBase64Encoded": false } ``` ------ ## Lambda function response format The payload format version determines the structure of the response that your Lambda function must return. ### Lambda function response for format 1.0 With the `1.0` format version, Lambda integrations must return a response in the following JSON format: **Example** ``` { "isBase64Encoded": true|false, "statusCode": httpStatusCode, "headers": { "headername": "headervalue", ... }, "multiValueHeaders": { "headername": ["headervalue", "headervalue2", ...], ... }, "body": "..." } ``` ### Lambda function response for format 2.0 With the `2.0` format version, API Gateway can infer the response format for you. API Gateway makes the following assumptions if your Lambda function returns valid JSON and doesn't return a `statusCode`: + `isBase64Encoded` is `false`. + `statusCode` is `200`. + `content-type` is `application/json`. + `body` is the function's response. The following examples show the output of a Lambda function and API Gateway's interpretation. | Lambda function output | API Gateway interpretation | | --- | --- | | 
"Hello from Lambda!"
| 
{
  "isBase64Encoded": false,
  "statusCode": 200,
  "body": "Hello from Lambda!",
  "headers": {
    "content-type": "application/json"
  }
}
| | 
{ "message": "Hello from Lambda!" }
| 
{
  "isBase64Encoded": false,
  "statusCode": 200,
  "body": "{ \"message\": \"Hello from Lambda!\" }",
  "headers": {
    "content-type": "application/json"
  }
}
| To customize the response, your Lambda function should return a response with the following format. ``` { "cookies" : ["cookie1", "cookie2"], "isBase64Encoded": true|false, "statusCode": httpStatusCode, "headers": { "headername": "headervalue", ... }, "body": "Hello from Lambda!" } ```