使用aws-sdk 中的 AWS.Lambda 承诺接口调用 lambda 比使用回调更容易。
此示例函数允许您从另一个 lambda 同步调用 lambda（它使用 'RequestResponse' 作为 InvocationType，因此您可以获取调用的 lambda 返回的值）。
如果使用'Event'（用于异步调用），则无法获取被调用的lambda返回的值，只能检测该lambda是否可以调用成功。它适用于不需要从调用的 lambda 获取返回值的情况。
//
// Full example of a lambda that calls another lambda
//
// (create a lambda in AWS with this code)
//
'use strict';
//
// Put here the name of the function you want to call
//
const g_LambdaFunctionName = 'PUT_HERE_THE_INVOKED_LAMBDA_NAME'; // <======= PUT THE DESIRED VALUE
const AWS = require('aws-sdk');
const lambda = new AWS.Lambda;
//
// Expected use:
//
// // (payload can be an object or a JSON string, for example)
// let var = await invokeLambda(lambdaFunctionName, payload);
//
const invokeLambda = async (lambdaFunctionName, payload) => {
console.log('>>> Entering invokeLambda');
// If the payload isn't a JSON string, we convert it to JSON
let payloadStr;
if (typeof payload === 'string')
{
console.log('invokeLambda: payload parameter is already a string: ', payload);
payloadStr = payload;
}
else
{
payloadStr = JSON.stringify(payload, null, 2);
console.log('invokeLambda: converting payload parameter to a string: ', payloadStr);
}
let params = {
FunctionName : lambdaFunctionName, /* string type, required */
// ClientContext : '', /* 'STRING_VALUE' */
InvocationType : 'RequestResponse', /* string type: 'Event' (async)| 'RequestResponse' (sync) | 'DryRun' (validate parameters y permissions) */
// InvocationType : 'Event',
LogType : 'None', /* string type: 'None' | 'Tail' */
// LogType : 'Tail',
Payload : payloadStr, /* Buffer.from('...') || 'JSON_STRING' */ /* Strings will be Base-64 encoded on your behalf */
// Qualifier : '', /* STRING_VALUE' */
};
//
// TODO/FIXME: add try/catch to protect this code from failures (non-existent lambda, execution errors in lambda)
//
const lambdaResult = await lambda.invoke(params).promise();
console.log('Results from invoking lambda ' + lambdaFunctionName + ': ' , JSON.stringify(lambdaResult, null, 2) );
// If you use LogType = 'Tail', you'll obtain the logs in lambdaResult.LogResult.
// If you use 'None', there will not exist that field in the response.
if (lambdaResult.LogResult)
{
console.log('Logs of lambda execution: ', Buffer.from(lambdaResult.LogResult, 'base64').toString());
}
console.log('invokeLambdaSync::lambdaResult: ', lambdaResult);
console.log('<<< Returning from invokeLambda, with lambdaResult: ', JSON.stringify(lambdaResult, null, 2));
// The actual value returned by the lambda it is lambdaResult.Payload
// There are other fields (some of them are optional)
return lambdaResult;
};
//
// We'll assign this as the calling lambda handler.
//
const callingFunc = async (event) => {
//
// in this example We obtain the lambda name from a global variable
//
const lambdaFunctionName = g_LambdaFunctionName;
// const payload = '{"param1" : "value1"}';
const payload = event;
//
// invokeLambda has to be called from a async function
// (to be able to use await)
//
const result = await invokeLambda(lambdaFunctionName, payload);
console.log('result: ', result);
};
// Assing handler function
exports.handler = callingFunc;
注意你应该在invokeLambda之前使用await：
...
//
// Called from another async function
//
const result = await invokeLambda(lambdaFunctionName, payload);
...
一些带有附加信息的相关链接：