Node.js 12.x环境下Lambda调用POST API的实现、参数传递与报错解决

初始实现代码 #

在Node.js 12.x运行时的Lambda函数中，最初的POST调用实现直接依赖第三方request模块，代码内容如下：

var posturl = "My post api path";
var jsonData = "{'password':'abcdef','domain':'www.mydomain.com','username':'abc.def'}";
var req = require('request');
const params = {
    url: posturl,
    headers: { 'jsonData': jsonData }
};
req.post(params, function(err, res, body) {
    if(err){
        console.log('------error------', err);
    } else{
        console.log('------success--------', body);
    }
});

运行异常 #

通过Step Functions状态机触发Lambda执行时，返回的错误信息如下：

{
  "errorType": "Error",
  "errorMessage": "Cannot find module 'request'\nRequire stack:\n- /var/task/index.js\n- /var/runtime/UserFunction.js\n- /var/runtime/index.js",
  "trace": [
    "Error: Cannot find module 'request'",
    "Require stack:",
    "- /var/task/index.js",
    "- /var/runtime/UserFunction.js",
    "- /var/runtime/index.js",
    "    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:815:15)",
    "    at Function.Module._load (internal/modules/cjs/loader.js:667:27)",
    "    at Module.require (internal/modules/cjs/loader.js:887:19)",
    "    at require (internal/modules/cjs/helpers.js:74:18)",
    "    at Runtime.exports.handler (/var/task/index.js:8:14)",
    "    at Runtime.handleOnce (/var/runtime/Runtime.js:66:25)"
  ]
}

核心待解决问题 #

• 如何在Lambda函数中正确发起POST API调用
• 接口要求必须通过jsonData键传递完整业务数据，缺少该字段接口将无法正常响应，如何在调用时正确构造传递参数
• 服务调用完成后，如何正确解析接口返回的响应内容

调整后的尝试实现 #

后续为了绕开第三方模块加载问题，改用Node.js内置http模块实现调用，对应代码如下：

exports.handler = (event, context, callback) => {
    const http = require('http');
    const data = JSON.stringify({
        password: 'mypassword',
        domain: 'www.mydomain.com',
        username: 'myusername'
    });

    const options = {
        hostname: 'http://abc.mydomain.com',
        path: 'remaining path with ticket',
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
            'Content-Length': data.length
        }
    };

    const req = http.request(options, (res) => {
        let resData = '';
        console.log('Status Code:', res.statusCode);

        res.on('data', (chunk) => {
            resData += chunk;
        });

        res.on('end', () => {
            console.log('Body: ', JSON.parse(resData));
        });

    }).on("error", (err) => {
        console.log("Error: ", err.message);
    });

    req.write(data);
    req.end();  
};

注：该实现暂未按接口要求在请求头中携带jsonData字段

内容的提问来源于stack exchange，提问作者Matthew Pans