AWS新手的30天之旅 - 21. Lambda & API Gateway

12th鐵人賽 aws

Charles

2020-10-01 11:46:53

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What is Lambda

你可以透過Lambda執行程式碼，而不必去管理Server建置、底層os設定、vm管理、要給多少cpu, memory，而只需要專注在商業邏輯的撰寫即可。

使用 AWS Lambda 執行程式碼，不必佈建或管理伺服器。您只需為使用的運算時間支付費用。

如何使用Lambda

參考這篇進行教學

建立Lambda function

進入AWS console後，搜尋「Lambda」後並進入

建立function
一開始一定會是空的，請選擇右上角的「Create function」

輸入function name, 並選擇 Nodejs 12.x

選擇Change default execution role, 並使用Create new role from AWS policy templates以及輸入role name
完成後直接點右下角的「Create function」

往下拉到Function code的部分，貼上以下的程式碼，並選擇Deploy

'use strict';
console.log('Loading hello world function');
 
exports.handler = async (event) => {
    let name = "you";
    let city = 'World';
    let time = 'day';
    let day = '';
    let responseCode = 200;
    console.log("request: " + JSON.stringify(event));
    
    if (event.queryStringParameters && event.queryStringParameters.name) {
        console.log("Received name: " + event.queryStringParameters.name);
        name = event.queryStringParameters.name;
    }
    
    if (event.queryStringParameters && event.queryStringParameters.city) {
        console.log("Received city: " + event.queryStringParameters.city);
        city = event.queryStringParameters.city;
    }
    
    if (event.headers && event.headers['day']) {
        console.log("Received day: " + event.headers.day);
        day = event.headers.day;
    }
    
    if (event.body) {
        let body = JSON.parse(event.body)
        if (body.time) 
            time = body.time;
    }
 
    let greeting = `Good ${time}, ${name} of ${city}.`;
    if (day) greeting += ` Happy ${day}!`;

    let responseBody = {
        message: greeting,
        input: event
    };
    
    // The output from a Lambda proxy integration must be 
    // in the following JSON object. The 'headers' property 
    // is for custom response headers in addition to standard 
    // ones. The 'body' property  must be a JSON string. For 
    // base64-encoded payload, you must also set the 'isBase64Encoded'
    // property to 'true'.
    let response = {
        statusCode: responseCode,
        headers: {
            "x-custom-header" : "my custom header value"
        },
        body: JSON.stringify(responseBody)
    };
    console.log("response: " + JSON.stringify(response))
    return response;
};

此時ldambda還沒有辦法對外，還需要建立API Gateway才行