The way to signup with KAKAO social provider using Amazon Cognito and AWS Amplify: step 05(Post Confirmation Cognito Lambda Trigger)

add-to-group.js

// amplify/backend/function/{amplify's auth Resource name}PostConfirmation/src/add-to-group.js
/* eslint-disable-line */ const aws = require('aws-sdk');

exports.handler = async (event, context, callback) => {
  const cognitoidentityserviceprovider = new aws.CognitoIdentityServiceProvider({ apiVersion: '2016-04-18' });
  const GroupName = event.request.clientMetadata.GroupName;
  const addUserParams = {
    GroupName,
    UserPoolId: event.userPoolId,
    Username: event.userName,
  };

  try {
    await cognitoidentityserviceprovider.adminAddUserToGroup(addUserParams).promise();
    callback(null, event);
  } catch (e) {
    callback(e);
  }
};