在函数中使用键值对

您可以在函数中使用键值存储中的键值对。

此示例演示了一个函数，该函数使用 HTTP 请求中的 URL 内容，在键值存储中查找自定义路径。然后，CloudFront 使用该自定义路径来发出请求。此函数有助于管理作为网站一部分的多个路径。

例如，如果较早的博客具有源路径 /blog-v1，而新博客具有源路径 /blog-v2，则此函数可以查找传入请求的 URL 路径，并将 URL 路径 (/blog-v1) 重写为新版本的博客 (/blog-v2)。

import cf from 'cloudfront';

// This fails if there is no key value store associated with the function
const kvsHandle = cf.kvs();

// Remember to associate the KVS with your function before referencing KVS in your code.
// https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/kvs-with-functions-associate.html
async function handler(event) {
    const request = event.request;
    // Use the first segment of the pathname as key
    // For example http(s)://domain/key/something/else
    const pathSegments = request.uri.split('/')
    const key = pathSegments[1]
    try {
        // Replace the first path of the pathname with the value of the key
        // For example http(s)://domain/value/something/else
        pathSegments[1] = await kvsHandle.get(key);
        const newUri = pathSegments.join('/');
        console.log(`${request.uri} -> ${newUri}`)
        request.uri = newUri;
    } catch (err) {
        // No change to the pathname if the key is not found
        console.log(`${request.uri} | ${err}`);
    }
    return request;
}