Example AWS Lambda function that executes AWS AppSync GraphQL Mutation using AWS Amplify

lambda-execute-appsync-mutation.js

const Amplify = require('aws-amplify');

Amplify.default.configure({
  aws_appsync_graphqlEndpoint: 'https://something.appsync-api.eu-west-1.amazonaws.com/graphql',
  aws_appsync_region: 'eu-west-1',
  aws_appsync_authenticationType: 'API_KEY',
  aws_appsync_apiKey: 'yourkey'
});

const mutation = `mutation CreatePerson($firstName: String!, $lastName: String!, bankAccountBalance: Float!) {
  createPerson(firstName: $firstName, lastName: $lastName, bankAccountBalance: $bankAccountBalance) {
    firstName
  }
}`;

exports.handler = async (event) => {

  // Let's assume that the incoming event will at least have the following fields (and maybe more):
  // { firstName: 'Edsger', lastName: 'Dijkstra', bankAccountBalance: 0.0 }
  
  await Amplify.API.graphql(Amplify.graphqlOperation(mutation, event));
 
};

Not sure how that works with the environment variables. But if you get aws-exports.js in your Lambda bundle from an Amplify build you can just read that.