本文為英文版的機器翻譯版本,如內容有任何歧義或不一致之處,概以英文版為準。
Lambda@Edge 範例函數
請參閱下列範例,以便搭配 Amazon 使用 Lambda 函數 CloudFront。
注意
如果您為 Lambda @Edge 函數選擇執行階段 Node.js 18 或更新版本,系統會自動為您建立index.mjs
檔案。若要使用下列程式碼範例,請將index.mjs
檔案重新命名index.js
為。
一般範例
下列範例顯示在中使用 Lambda @Edge 的常用方法 CloudFront。
範例:A/B 測試
您可以使用下列範例測試兩種不同版本的影像,而不需要建立重新導向或變更 URL。此範例會讀取檢視器請求中的 Cookie,並據此修改請求 URL。如果檢視器未傳送具有其中一個預期值的 Cookie,此範例會將檢視器隨機指派給其中一個 URL。
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; const headers = request.headers; if (request.uri !== '/experiment-pixel.jpg') { // do not process if this is not an A-B test request callback(null, request); return; } const cookieExperimentA = 'X-Experiment-Name=A'; const cookieExperimentB = 'X-Experiment-Name=B'; const pathExperimentA = '/experiment-group/control-pixel.jpg'; const pathExperimentB = '/experiment-group/treatment-pixel.jpg'; /* * Lambda at the Edge headers are array objects. * * Client may send multiple Cookie headers, i.e.: * > GET /viewerRes/test HTTP/1.1 * > User-Agent: curl/7.18.1 (x86_64-unknown-linux-gnu) libcurl/7.18.1 OpenSSL/1.0.1u zlib/1.2.3 * > Cookie: First=1; Second=2 * > Cookie: ClientCode=abc * > Host: example.com * * You can access the first Cookie header at headers["cookie"][0].value * and the second at headers["cookie"][1].value. * * Header values are not parsed. In the example above, * headers["cookie"][0].value is equal to "First=1; Second=2" */ let experimentUri; if (headers.cookie) { for (let i = 0; i < headers.cookie.length; i++) { if (headers.cookie[i].value.indexOf(cookieExperimentA) >= 0) { console.log('Experiment A cookie found'); experimentUri = pathExperimentA; break; } else if (headers.cookie[i].value.indexOf(cookieExperimentB) >= 0) { console.log('Experiment B cookie found'); experimentUri = pathExperimentB; break; } } } if (!experimentUri) { console.log('Experiment cookie has not been found. Throwing dice...'); if (Math.random() < 0.75) { experimentUri = pathExperimentA; } else { experimentUri = pathExperimentB; } } request.uri = experimentUri; console.log(`Request uri set to "${request.uri}"`); callback(null, request); };
- Python
-
import json import random def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] headers = request['headers'] if request['uri'] != '/experiment-pixel.jpg': # Not an A/B Test return request cookieExperimentA, cookieExperimentB = 'X-Experiment-Name=A', 'X-Experiment-Name=B' pathExperimentA, pathExperimentB = '/experiment-group/control-pixel.jpg', '/experiment-group/treatment-pixel.jpg' ''' Lambda at the Edge headers are array objects. Client may send multiple cookie headers. For example: > GET /viewerRes/test HTTP/1.1 > User-Agent: curl/7.18.1 (x86_64-unknown-linux-gnu) libcurl/7.18.1 OpenSSL/1.0.1u zlib/1.2.3 > Cookie: First=1; Second=2 > Cookie: ClientCode=abc > Host: example.com You can access the first Cookie header at headers["cookie"][0].value and the second at headers["cookie"][1].value. Header values are not parsed. In the example above, headers["cookie"][0].value is equal to "First=1; Second=2" ''' experimentUri = "" for cookie in headers.get('cookie', []): if cookieExperimentA in cookie['value']: print("Experiment A cookie found") experimentUri = pathExperimentA break elif cookieExperimentB in cookie['value']: print("Experiment B cookie found") experimentUri = pathExperimentB break if not experimentUri: print("Experiment cookie has not been found. Throwing dice...") if random.random() < 0.75: experimentUri = pathExperimentA else: experimentUri = pathExperimentB request['uri'] = experimentUri print(f"Request uri set to {experimentUri}") return request
範例:覆寫回應標頭
以下範例說明如何根據另一個標頭的值變更回應標頭的值。
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const response = event.Records[0].cf.response; const headers = response.headers; const headerNameSrc = 'X-Amz-Meta-Last-Modified'; const headerNameDst = 'Last-Modified'; if (headers[headerNameSrc.toLowerCase()]) { headers[headerNameDst.toLowerCase()] = [ headers[headerNameSrc.toLowerCase()][0], ]; console.log(`Response header "${headerNameDst}" was set to ` + `"${headers[headerNameDst.toLowerCase()][0].value}"`); } callback(null, response); };
- Python
-
import json def lambda_handler(event, context): response = event["Records"][0]["cf"]["response"] headers = response["headers"] headerNameSrc = "X-Amz-Meta-Last-Modified" headerNameDst = "Last-Modified" if headers.get(headerNameSrc.lower(), None): headers[headerNameDst.lower()] = [headers[headerNameSrc.lower()][0]] print(f"Response header {headerNameDst.lower()} was set to {headers[headerNameSrc.lower()][0]}") return response
產生回應-範例
下列範例說明如何使用 Lambda @Edge 產生回應。
示例:提供靜態內容(生成的響應)
以下範例說明如何使用 Lambda 函數提供靜態網站內容,其可減少原始伺服器的負載,並降低整體延遲。
注意
您可以針對檢視器要求及原始伺服器請求事件產生 HTTP 回應。如需詳細資訊,請參閱 在要求觸發程序中產生 HTTP 回應。
您也可以在原始伺服器回應請求事件中取代或移除 HTTP 回應的主體。如需詳細資訊,請參閱 更新原始響應觸發器中的 HTTP 響應。
- Node.js
-
'use strict'; const content = ` <\!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>Simple Lambda@Edge Static Content Response</title> </head> <body> <p>Hello from Lambda@Edge!</p> </body> </html> `; exports.handler = (event, context, callback) => { /* * Generate HTTP OK response using 200 status code with HTML body. */ const response = { status: '200', statusDescription: 'OK', headers: { 'cache-control': [{ key: 'Cache-Control', value: 'max-age=100' }], 'content-type': [{ key: 'Content-Type', value: 'text/html' }] }, body: content, }; callback(null, response); };
- Python
-
import json CONTENT = """ <\!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>Simple Lambda@Edge Static Content Response</title> </head> <body> <p>Hello from Lambda@Edge!</p> </body> </html> """ def lambda_handler(event, context): # Generate HTTP OK response using 200 status code with HTML body. response = { 'status': '200', 'statusDescription': 'OK', 'headers': { 'cache-control': [ { 'key': 'Cache-Control', 'value': 'max-age=100' } ], "content-type": [ { 'key': 'Content-Type', 'value': 'text/html' } ] }, 'body': CONTENT } return response
範例:產生 HTTP 重新導向 (產生的回應)
以下範例說明如何產生 HTTP 重新導向。
注意
您可以針對檢視器要求及原始伺服器請求事件產生 HTTP 回應。如需詳細資訊,請參閱 在要求觸發程序中產生 HTTP 回應。
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { /* * Generate HTTP redirect response with 302 status code and Location header. */ const response = { status: '302', statusDescription: 'Found', headers: { location: [{ key: 'Location', value: 'https://docs.aws.amazon.com/lambda/latest/dg/lambda-edge.html', }], }, }; callback(null, response); };
- Python
-
def lambda_handler(event, context): # Generate HTTP redirect response with 302 status code and Location header. response = { 'status': '302', 'statusDescription': 'Found', 'headers': { 'location': [{ 'key': 'Location', 'value': 'https://docs.aws.amazon.com/lambda/latest/dg/lambda-edge.html' }] } } return response
查詢字串-範例
下列範例說明如何搭配查詢字串使用 Lambda @Edge。
範例:根據查詢字串參數新增標頭
以下範例說明如何取得查詢字串參數的鍵值對,然後根據這些值新增標頭。
- Node.js
-
'use strict'; const querystring = require('querystring'); exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; /* When a request contains a query string key-value pair but the origin server * expects the value in a header, you can use this Lambda function to * convert the key-value pair to a header. Here's what the function does: * 1. Parses the query string and gets the key-value pair. * 2. Adds a header to the request using the key-value pair that the function got in step 1. */ /* Parse request querystring to get javascript object */ const params = querystring.parse(request.querystring); /* Move auth param from querystring to headers */ const headerName = 'Auth-Header'; request.headers[headerName.toLowerCase()] = [{ key: headerName, value: params.auth }]; delete params.auth; /* Update request querystring */ request.querystring = querystring.stringify(params); callback(null, request); };
- Python
-
from urllib.parse import parse_qs, urlencode def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] ''' When a request contains a query string key-value pair but the origin server expects the value in a header, you can use this Lambda function to convert the key-value pair to a header. Here's what the function does: 1. Parses the query string and gets the key-value pair. 2. Adds a header to the request using the key-value pair that the function got in step 1. ''' # Parse request querystring to get dictionary/json params = {k : v[0] for k, v in parse_qs(request['querystring']).items()} # Move auth param from querystring to headers headerName = 'Auth-Header' request['headers'][headerName.lower()] = [{'key': headerName, 'value': params['auth']}] del params['auth'] # Update request querystring request['querystring'] = urlencode(params) return request
範例:正規化查詢字串參數以改善快取命中率
下列範例會示範如何在將要求 CloudFront 轉寄至來源之前,對查詢字串進行下列變更,藉此改善快取命中率:
-
依字母排序鍵值組的參數名稱。
-
將鍵值組變更為小寫。
如需詳細資訊,請參閱 根據查詢字串參數快取內容。
- Node.js
-
'use strict'; const querystring = require('querystring'); exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; /* When you configure a distribution to forward query strings to the origin and * to cache based on an allowlist of query string parameters, we recommend * the following to improve the cache-hit ratio: * - Always list parameters in the same order. * - Use the same case for parameter names and values. * * This function normalizes query strings so that parameter names and values * are lowercase and parameter names are in alphabetical order. * * For more information, see: * https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/QueryStringParameters.html */ console.log('Query String: ', request.querystring); /* Parse request query string to get javascript object */ const params = querystring.parse(request.querystring.toLowerCase()); const sortedParams = {}; /* Sort param keys */ Object.keys(params).sort().forEach(key => { sortedParams[key] = params[key]; }); /* Update request querystring with normalized */ request.querystring = querystring.stringify(sortedParams); callback(null, request); };
- Python
-
from urllib.parse import parse_qs, urlencode def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] ''' When you configure a distribution to forward query strings to the origin and to cache based on an allowlist of query string parameters, we recommend the following to improve the cache-hit ratio: Always list parameters in the same order. - Use the same case for parameter names and values. This function normalizes query strings so that parameter names and values are lowercase and parameter names are in alphabetical order. For more information, see: https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/QueryStringParameters.html ''' print("Query string: ", request["querystring"]) # Parse request query string to get js object params = {k : v[0] for k, v in parse_qs(request['querystring'].lower()).items()} # Sort param keys sortedParams = sorted(params.items(), key=lambda x: x[0]) # Update request querystring with normalized request['querystring'] = urlencode(sortedParams) return request
範例:將未驗證的使用者重新導向至登入頁面
以下範例說明,如果尚未輸入他們的登入資料,如何將使用者重新導向至登入頁面。
- Node.js
-
'use strict'; function parseCookies(headers) { const parsedCookie = {}; if (headers.cookie) { headers.cookie[0].value.split(';').forEach((cookie) => { if (cookie) { const parts = cookie.split('='); parsedCookie[parts[0].trim()] = parts[1].trim(); } }); } return parsedCookie; } exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; const headers = request.headers; /* Check for session-id in request cookie in viewer-request event, * if session-id is absent, redirect the user to sign in page with original * request sent as redirect_url in query params. */ /* Check for session-id in cookie, if present then proceed with request */ const parsedCookies = parseCookies(headers); if (parsedCookies && parsedCookies['session-id']) { callback(null, request); return; } /* URI encode the original request to be sent as redirect_url in query params */ const encodedRedirectUrl = encodeURIComponent(`https://${headers.host[0].value}${request.uri}?${request.querystring}`); const response = { status: '302', statusDescription: 'Found', headers: { location: [{ key: 'Location', value: `https://www.example.com/signin?redirect_url=${encodedRedirectUrl}`, }], }, }; callback(null, response); };
- Python
-
import urllib def parseCookies(headers): parsedCookie = {} if headers.get('cookie'): for cookie in headers['cookie'][0]['value'].split(';'): if cookie: parts = cookie.split('=') parsedCookie[parts[0].strip()] = parts[1].strip() return parsedCookie def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] headers = request['headers'] ''' Check for session-id in request cookie in viewer-request event, if session-id is absent, redirect the user to sign in page with original request sent as redirect_url in query params. ''' # Check for session-id in cookie, if present, then proceed with request parsedCookies = parseCookies(headers) if parsedCookies and parsedCookies['session-id']: return request # URI encode the original request to be sent as redirect_url in query params redirectUrl = "https://%s%s?%s" % (headers['host'][0]['value'], request['uri'], request['querystring']) encodedRedirectUrl = urllib.parse.quote_plus(redirectUrl.encode('utf-8')) response = { 'status': '302', 'statusDescription': 'Found', 'headers': { 'location': [{ 'key': 'Location', 'value': 'https://www.example.com/signin?redirect_url=%s' % encodedRedirectUrl }] } } return response
根據國家/地區或裝置類型標頭個人化 - 範例
下列範例說明如何使用 Lambda @Edge,根據檢視器所使用的位置或裝置類型自訂行為。
範例:將檢視者要求重新導向至特定國家/地區的 URL
以下範例說明如何產生含國家/地區特定 URL 的 HTTP 重新導向回應,並將回應傳回至檢視器。當您希望提供特定國家的回應時,此方法很有用。例如:
-
如果您有國家/地區特定的子網域 (例如 us.example.com 和 tw.example.com),當檢視器請求 example.com 時,您可以產生一個重新導向回應。
-
如果您在串流視訊,但沒有在特定國家/地區串流此內容的權利,您可以在該國家/地區將使用者重新導向到說明他們為何無法檢視影片的頁面。
注意下列事項:
-
您必須根據
CloudFront-Viewer-Country
標頭設定您的分佈為快取。如需詳細資訊,請參閱 根據選取請求標頭的快取。 -
CloudFront 在檢視器要求事件之後加入
CloudFront-Viewer-Country
標頭。要使用此範例,您必須建立原始伺服器請求事件的觸發。
- Node.js
-
'use strict'; /* This is an origin request function */ exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; const headers = request.headers; /* * Based on the value of the CloudFront-Viewer-Country header, generate an * HTTP status code 302 (Redirect) response, and return a country-specific * URL in the Location header. * NOTE: 1. You must configure your distribution to cache based on the * CloudFront-Viewer-Country header. For more information, see * https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers * 2. CloudFront adds the CloudFront-Viewer-Country header after the viewer * request event. To use this example, you must create a trigger for the * origin request event. */ let url = 'https://example.com/'; if (headers['cloudfront-viewer-country']) { const countryCode = headers['cloudfront-viewer-country'][0].value; if (countryCode === 'TW') { url = 'https://tw.example.com/'; } else if (countryCode === 'US') { url = 'https://us.example.com/'; } } const response = { status: '302', statusDescription: 'Found', headers: { location: [{ key: 'Location', value: url, }], }, }; callback(null, response); };
- Python
-
# This is an origin request function def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] headers = request['headers'] ''' Based on the value of the CloudFront-Viewer-Country header, generate an HTTP status code 302 (Redirect) response, and return a country-specific URL in the Location header. NOTE: 1. You must configure your distribution to cache based on the CloudFront-Viewer-Country header. For more information, see https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers 2. CloudFront adds the CloudFront-Viewer-Country header after the viewer request event. To use this example, you must create a trigger for the origin request event. ''' url = 'https://example.com/' viewerCountry = headers.get('cloudfront-viewer-country') if viewerCountry: countryCode = viewerCountry[0]['value'] if countryCode == 'TW': url = 'https://tw.example.com/' elif countryCode == 'US': url = 'https://us.example.com/' response = { 'status': '302', 'statusDescription': 'Found', 'headers': { 'location': [{ 'key': 'Location', 'value': url }] } } return response
範例:根據裝置提供不同版本的物件
以下範例說明如何根據使用者使用的裝置類型,提供不同的物件版本,例如行動裝置或平板電腦。注意下列事項:
-
您必須根據
CloudFront-Is-*-Viewer
標頭設定您的分佈為快取。如需詳細資訊,請參閱 根據選取請求標頭的快取。 -
CloudFront 在檢視器要求事件之後加入
CloudFront-Is-*-Viewer
標頭。要使用此範例,您必須建立原始伺服器請求事件的觸發。
- Node.js
-
'use strict'; /* This is an origin request function */ exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; const headers = request.headers; /* * Serve different versions of an object based on the device type. * NOTE: 1. You must configure your distribution to cache based on the * CloudFront-Is-*-Viewer headers. For more information, see * the following documentation: * https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers * https://docs.aws.amazon.com/console/cloudfront/cache-on-device-type * 2. CloudFront adds the CloudFront-Is-*-Viewer headers after the viewer * request event. To use this example, you must create a trigger for the * origin request event. */ const desktopPath = '/desktop'; const mobilePath = '/mobile'; const tabletPath = '/tablet'; const smarttvPath = '/smarttv'; if (headers['cloudfront-is-desktop-viewer'] && headers['cloudfront-is-desktop-viewer'][0].value === 'true') { request.uri = desktopPath + request.uri; } else if (headers['cloudfront-is-mobile-viewer'] && headers['cloudfront-is-mobile-viewer'][0].value === 'true') { request.uri = mobilePath + request.uri; } else if (headers['cloudfront-is-tablet-viewer'] && headers['cloudfront-is-tablet-viewer'][0].value === 'true') { request.uri = tabletPath + request.uri; } else if (headers['cloudfront-is-smarttv-viewer'] && headers['cloudfront-is-smarttv-viewer'][0].value === 'true') { request.uri = smarttvPath + request.uri; } console.log(`Request uri set to "${request.uri}"`); callback(null, request); };
- Python
-
# This is an origin request function def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] headers = request['headers'] ''' Serve different versions of an object based on the device type. NOTE: 1. You must configure your distribution to cache based on the CloudFront-Is-*-Viewer headers. For more information, see the following documentation: https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers https://docs.aws.amazon.com/console/cloudfront/cache-on-device-type 2. CloudFront adds the CloudFront-Is-*-Viewer headers after the viewer request event. To use this example, you must create a trigger for the origin request event. ''' desktopPath = '/desktop'; mobilePath = '/mobile'; tabletPath = '/tablet'; smarttvPath = '/smarttv'; if 'cloudfront-is-desktop-viewer' in headers and headers['cloudfront-is-desktop-viewer'][0]['value'] == 'true': request['uri'] = desktopPath + request['uri'] elif 'cloudfront-is-mobile-viewer' in headers and headers['cloudfront-is-mobile-viewer'][0]['value'] == 'true': request['uri'] = mobilePath + request['uri'] elif 'cloudfront-is-tablet-viewer' in headers and headers['cloudfront-is-tablet-viewer'][0]['value'] == 'true': request['uri'] = tabletPath + request['uri'] elif 'cloudfront-is-smarttv-viewer' in headers and headers['cloudfront-is-smarttv-viewer'][0]['value'] == 'true': request['uri'] = smarttvPath + request['uri'] print("Request uri set to %s" % request['uri']) return request
以內容為基礎的動態原始伺服器選擇 - 範例
下列範例顯示如何使用 Lambda @Edge,根據請求中的資訊路由到不同的來源。
主題
範例:使用原始請求觸發程序從自訂來源變更為 Amazon S3 來源
此函數示範如何使用 origin-request 觸發條件,根據請求屬性從自訂原始伺服器變更至內容被擷取的 Amazon S3 原始伺服器。
- Node.js
-
'use strict'; const querystring = require('querystring'); exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; /** * Reads query string to check if S3 origin should be used, and * if true, sets S3 origin properties. */ const params = querystring.parse(request.querystring); if (params['useS3Origin']) { if (params['useS3Origin'] === 'true') { const s3DomainName = 'my-bucket.s3.amazonaws.com'; /* Set S3 origin fields */ request.origin = { s3: { domainName: s3DomainName, region: '', authMethod: 'none', path: '', customHeaders: {} } }; request.headers['host'] = [{ key: 'host', value: s3DomainName}]; } } callback(null, request); };
- Python
-
from urllib.parse import parse_qs def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] ''' Reads query string to check if S3 origin should be used, and if true, sets S3 origin properties ''' params = {k: v[0] for k, v in parse_qs(request['querystring']).items()} if params.get('useS3Origin') == 'true': s3DomainName = 'my-bucket.s3.amazonaws.com' # Set S3 origin fields request['origin'] = { 's3': { 'domainName': s3DomainName, 'region': '', 'authMethod': 'none', 'path': '', 'customHeaders': {} } } request['headers']['host'] = [{'key': 'host', 'value': s3DomainName}] return request
範例:使用來源請求觸發程序變更 Amazon S3 來源區域
此函數示範如何根據請求屬性,使用 origin-request 觸發條件來變更內容被擷取的 Amazon S3 原始伺服器。
在這個範例中,我們使用 CloudFront-Viewer-Country
標頭的值來將 S3 儲存貯體的網域名稱更新為較靠近檢視器的區域內的儲存貯體。這在數種方式中非常受用:
-
當指定的區域更靠近檢視器的國家/地區時,能減少延遲。
-
藉由確保該資料與請求來自位於相同國家/地區的原始伺服器,提供資料主權服務。
要使用此範例,須執行下列項目:
-
您必須根據
CloudFront-Viewer-Country
標頭設定您的分佈為快取。如需詳細資訊,請參閱 根據選取請求標頭的快取。 -
在原始請求事件中為此函數創建一個觸發器。 CloudFront在查看器請求事件之後添加
CloudFront-Viewer-Country
標題,因此要使用此示例,您必須確保該函數針對原始請求執行。
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; /** * This blueprint demonstrates how an origin-request trigger can be used to * change the origin from which the content is fetched, based on request properties. * In this example, we use the value of the CloudFront-Viewer-Country header * to update the S3 bucket domain name to a bucket in a Region that is closer to * the viewer. * * This can be useful in several ways: * 1) Reduces latencies when the Region specified is nearer to the viewer's * country. * 2) Provides data sovereignty by making sure that data is served from an * origin that's in the same country that the request came from. * * NOTE: 1. You must configure your distribution to cache based on the * CloudFront-Viewer-Country header. For more information, see * https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers * 2. CloudFront adds the CloudFront-Viewer-Country header after the viewer * request event. To use this example, you must create a trigger for the * origin request event. */ const countryToRegion = { 'DE': 'eu-central-1', 'IE': 'eu-west-1', 'GB': 'eu-west-2', 'FR': 'eu-west-3', 'JP': 'ap-northeast-1', 'IN': 'ap-south-1' }; if (request.headers['cloudfront-viewer-country']) { const countryCode = request.headers['cloudfront-viewer-country'][0].value; const region = countryToRegion[countryCode]; /** * If the viewer's country is not in the list you specify, the request * goes to the default S3 bucket you've configured. */ if (region) { /** * If you've set up OAI, the bucket policy in the destination bucket * should allow the OAI GetObject operation, as configured by default * for an S3 origin with OAI. Another requirement with OAI is to provide * the Region so it can be used for the SIGV4 signature. Otherwise, the * Region is not required. */ request.origin.s3.region = region; const domainName = `my-bucket-in-${region}.s3.amazonaws.com`; request.origin.s3.domainName = domainName; request.headers['host'] = [{ key: 'host', value: domainName }]; } } callback(null, request); };
- Python
-
def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] ''' This blueprint demonstrates how an origin-request trigger can be used to change the origin from which the content is fetched, based on request properties. In this example, we use the value of the CloudFront-Viewer-Country header to update the S3 bucket domain name to a bucket in a Region that is closer to the viewer. This can be useful in several ways: 1) Reduces latencies when the Region specified is nearer to the viewer's country. 2) Provides data sovereignty by making sure that data is served from an origin that's in the same country that the request came from. NOTE: 1. You must configure your distribution to cache based on the CloudFront-Viewer-Country header. For more information, see https://docs.aws.amazon.com/console/cloudfront/cache-on-selected-headers 2. CloudFront adds the CloudFront-Viewer-Country header after the viewer request event. To use this example, you must create a trigger for the origin request event. ''' countryToRegion = { 'DE': 'eu-central-1', 'IE': 'eu-west-1', 'GB': 'eu-west-2', 'FR': 'eu-west-3', 'JP': 'ap-northeast-1', 'IN': 'ap-south-1' } viewerCountry = request['headers'].get('cloudfront-viewer-country') if viewerCountry: countryCode = viewerCountry[0]['value'] region = countryToRegion.get(countryCode) # If the viewer's country in not in the list you specify, the request # goes to the default S3 bucket you've configured if region: ''' If you've set up OAI, the bucket policy in the destination bucket should allow the OAI GetObject operation, as configured by default for an S3 origin with OAI. Another requirement with OAI is to provide the Region so it can be used for the SIGV4 signature. Otherwise, the Region is not required. ''' request['origin']['s3']['region'] = region domainName = 'my-bucket-in-%s.s3.amazonaws.com' % region request['origin']['s3']['domainName'] = domainName request['headers']['host'] = [{'key': 'host', 'value': domainName}] return request
範例:使用原始請求觸發程序從 Amazon S3 來源變更為自訂來源
此函數示範如何根據請求屬性,使用原始伺服器請求觸發來變更內容被擷取的自訂原始伺服器。
- Node.js
-
'use strict'; const querystring = require('querystring'); exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; /** * Reads query string to check if custom origin should be used, and * if true, sets custom origin properties. */ const params = querystring.parse(request.querystring); if (params['useCustomOrigin']) { if (params['useCustomOrigin'] === 'true') { /* Set custom origin fields*/ request.origin = { custom: { domainName: 'www.example.com', port: 443, protocol: 'https', path: '', sslProtocols: ['TLSv1', 'TLSv1.1'], readTimeout: 5, keepaliveTimeout: 5, customHeaders: {} } }; request.headers['host'] = [{ key: 'host', value: 'www.example.com'}]; } } callback(null, request); };
- Python
-
from urllib.parse import parse_qs def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] # Reads query string to check if custom origin should be used, and # if true, sets custom origin properties params = {k: v[0] for k, v in parse_qs(request['querystring']).items()} if params.get('useCustomOrigin') == 'true': # Set custom origin fields request['origin'] = { 'custom': { 'domainName': 'www.example.com', 'port': 443, 'protocol': 'https', 'path': '', 'sslProtocols': ['TLSv1', 'TLSv1.1'], 'readTimeout': 5, 'keepaliveTimeout': 5, 'customHeaders': {} } } request['headers']['host'] = [{'key': 'host', 'value': 'www.example.com'}] return request
範例:使用來源請求觸發程序將流量從一個 Amazon S3 儲存貯體逐步傳輸到另一個儲存貯體
此功能示範如何以受控方式逐步將流量從一個 Amazon S3 儲存貯體傳輸到另一個儲存貯體。
- Node.js
-
'use strict'; function getRandomInt(min, max) { /* Random number is inclusive of min and max*/ return Math.floor(Math.random() * (max - min + 1)) + min; } exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; const BLUE_TRAFFIC_PERCENTAGE = 80; /** * This Lambda function demonstrates how to gradually transfer traffic from * one S3 bucket to another in a controlled way. * We define a variable BLUE_TRAFFIC_PERCENTAGE which can take values from * 1 to 100. If the generated randomNumber less than or equal to BLUE_TRAFFIC_PERCENTAGE, traffic * is re-directed to blue-bucket. If not, the default bucket that we've configured * is used. */ const randomNumber = getRandomInt(1, 100); if (randomNumber <= BLUE_TRAFFIC_PERCENTAGE) { const domainName = 'blue-bucket.s3.amazonaws.com'; request.origin.s3.domainName = domainName; request.headers['host'] = [{ key: 'host', value: domainName}]; } callback(null, request); };
- Python
-
import math import random def getRandomInt(min, max): # Random number is inclusive of min and max return math.floor(random.random() * (max - min + 1)) + min def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] BLUE_TRAFFIC_PERCENTAGE = 80 ''' This Lambda function demonstrates how to gradually transfer traffic from one S3 bucket to another in a controlled way. We define a variable BLUE_TRAFFIC_PERCENTAGE which can take values from 1 to 100. If the generated randomNumber less than or equal to BLUE_TRAFFIC_PERCENTAGE, traffic is re-directed to blue-bucket. If not, the default bucket that we've configured is used. ''' randomNumber = getRandomInt(1, 100) if randomNumber <= BLUE_TRAFFIC_PERCENTAGE: domainName = 'blue-bucket.s3.amazonaws.com' request['origin']['s3']['domainName'] = domainName request['headers']['host'] = [{'key': 'host', 'value': domainName}] return request
範例:使用來源要求觸發程式,根據國家/地區標頭變更原始網域名稱
此函數示範如何根據 CloudFront-Viewer-Country
標頭來變更原始伺服器的網域名稱,使內容能從靠近檢視者國家/地區的原始伺服器提供。
為您的分佈實施此功能可以擁有如下所述的優勢:
-
當指定的區域更靠近檢視器的國家/地區時,可減少延遲
-
藉由確保該資料與請求來自位於相同國家/地區的原始伺服器來提供資料主權服務
請注意,要啟用此功能,您必須根據 CloudFront-Viewer-Country
標頭設定您的分佈為快取。如需詳細資訊,請參閱 根據選取請求標頭的快取。
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; if (request.headers['cloudfront-viewer-country']) { const countryCode = request.headers['cloudfront-viewer-country'][0].value; if (countryCode === 'GB' || countryCode === 'DE' || countryCode === 'IE' ) { const domainName = 'eu.example.com'; request.origin.custom.domainName = domainName; request.headers['host'] = [{key: 'host', value: domainName}]; } } callback(null, request); };
- Python
-
def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] viewerCountry = request['headers'].get('cloudfront-viewer-country') if viewerCountry: countryCode = viewerCountry[0]['value'] if countryCode == 'GB' or countryCode == 'DE' or countryCode == 'IE': domainName = 'eu.example.com' request['origin']['custom']['domainName'] = domainName request['headers']['host'] = [{'key': 'host', 'value': domainName}] return request
更新錯誤狀態-範例
下列範例提供如何使用 Lambda @Edge 變更傳回給使用者的錯誤狀態的指引。
範例:使用來源回應觸發程序將錯誤狀態碼更新為 200
此函數示範如何更新回應狀態為 200 並產生靜態本文內容,以在以下案例傳回給檢視器:
-
函數在原始伺服器回應中觸發。
-
原始伺服器的回應狀態為錯誤狀態碼 (4xx 和 5xx)
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const response = event.Records[0].cf.response; /** * This function updates the response status to 200 and generates static * body content to return to the viewer in the following scenario: * 1. The function is triggered in an origin response * 2. The response status from the origin server is an error status code (4xx or 5xx) */ if (response.status >= 400 && response.status <= 599) { response.status = 200; response.statusDescription = 'OK'; response.body = 'Body generation example'; } callback(null, response); };
- Python
-
def lambda_handler(event, context): response = event['Records'][0]['cf']['response'] ''' This function updates the response status to 200 and generates static body content to return to the viewer in the following scenario: 1. The function is triggered in an origin response 2. The response status from the origin server is an error status code (4xx or 5xx) ''' if int(response['status']) >= 400 and int(response['status']) <= 599: response['status'] = 200 response['statusDescription'] = 'OK' response['body'] = 'Body generation example' return response
範例:使用來源回應觸發程序將錯誤狀態碼更新為 302
此函數示範如何更新 HTTP 狀態碼為 302,以重新導向到另一個由不同原始伺服器設定的路徑 (快取行為)。注意下列事項:
-
函數在原始伺服器回應中觸發。
-
原始伺服器的回應狀態為錯誤狀態碼 (4xx 和 5xx)
- Node.js
-
'use strict'; exports.handler = (event, context, callback) => { const response = event.Records[0].cf.response; const request = event.Records[0].cf.request; /** * This function updates the HTTP status code in the response to 302, to redirect to another * path (cache behavior) that has a different origin configured. Note the following: * 1. The function is triggered in an origin response * 2. The response status from the origin server is an error status code (4xx or 5xx) */ if (response.status >= 400 && response.status <= 599) { const redirect_path = `/plan-b/path?${request.querystring}`; response.status = 302; response.statusDescription = 'Found'; /* Drop the body, as it is not required for redirects */ response.body = ''; response.headers['location'] = [{ key: 'Location', value: redirect_path }]; } callback(null, response); };
- Python
-
def lambda_handler(event, context): response = event['Records'][0]['cf']['response'] request = event['Records'][0]['cf']['request'] ''' This function updates the HTTP status code in the response to 302, to redirect to another path (cache behavior) that has a different origin configured. Note the following: 1. The function is triggered in an origin response 2. The response status from the origin server is an error status code (4xx or 5xx) ''' if int(response['status']) >= 400 and int(response['status']) <= 599: redirect_path = '/plan-b/path?%s' % request['querystring'] response['status'] = 302 response['statusDescription'] = 'Found' # Drop the body as it is not required for redirects response['body'] = '' response['headers']['location'] = [{'key': 'Location', 'value': redirect_path}] return response
訪問請求主體-示例
下列範例說明如何使用 Lambda @Edge 處理 POST 要求。
注意
若要使用這些範例,您必須在分佈的 Lambda 函數關聯中啟用包含內文選項。依預設不會啟用此功能。
-
若要在 CloudFront 主控台中啟用此設定,請選取「在 Lambda 函數關聯中包含主體」的核取方塊。
-
若要在 CloudFront API 或使用中啟用此設定 AWS CloudFormation,請將
IncludeBody
欄位設定為true
中LambdaFunctionAssociation
。
範例:使用要求觸發程式來讀取 HTML 表單
此函數示範如何處理 HTML 表單 (Web 表單) 所產生 POST 請求的主體,例如「聯絡我們」表單。例如,您可能會有如下的 HTML 表單:
<html> <form action="https://example.com" method="post"> Param 1: <input type="text" name="name1"><br> Param 2: <input type="text" name="name2"><br> input type="submit" value="Submit"> </form> </html>
對於下面的示例函數,該函數必須在CloudFront 查看器請求或源請求中觸發。
- Node.js
-
'use strict'; const querystring = require('querystring'); /** * This function demonstrates how you can read the body of a POST request * generated by an HTML form (web form). The function is triggered in a * CloudFront viewer request or origin request event type. */ exports.handler = (event, context, callback) => { const request = event.Records[0].cf.request; if (request.method === 'POST') { /* HTTP body is always passed as base64-encoded string. Decode it. */ const body = Buffer.from(request.body.data, 'base64').toString(); /* HTML forms send the data in query string format. Parse it. */ const params = querystring.parse(body); /* For demonstration purposes, we only log the form fields here. * You can put your custom logic here. For example, you can store the * fields in a database, such as Amazon DynamoDB, and generate a response * right from your Lambda@Edge function. */ for (let param in params) { console.log(`For "${param}" user submitted "${params[param]}".\n`); } } return callback(null, request); };
- Python
-
import base64 from urllib.parse import parse_qs ''' Say there is a POST request body generated by an HTML such as: <html> <form action="https://example.com" method="post"> Param 1: <input type="text" name="name1"><br> Param 2: <input type="text" name="name2"><br> input type="submit" value="Submit"> </form> </html> ''' ''' This function demonstrates how you can read the body of a POST request generated by an HTML form (web form). The function is triggered in a CloudFront viewer request or origin request event type. ''' def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] if request['method'] == 'POST': # HTTP body is always passed as base64-encoded string. Decode it body = base64.b64decode(request['body']['data']) # HTML forms send the data in query string format. Parse it params = {k: v[0] for k, v in parse_qs(body).items()} ''' For demonstration purposes, we only log the form fields here. You can put your custom logic here. For example, you can store the fields in a database, such as Amazon DynamoDB, and generate a response right from your Lambda@Edge function. ''' for key, value in params.items(): print("For %s use submitted %s" % (key, value)) return request
範例:使用要求觸發程式來修改 HTML 表單
此函數示範如何修改 HTML 表單 (Web 表單) 所產生 POST 請求的主體。該功能在 CloudFront 查看器請求或源請求中觸發。
- Node.js
-
'use strict'; const querystring = require('querystring'); exports.handler = (event, context, callback) => { var request = event.Records[0].cf.request; if (request.method === 'POST') { /* Request body is being replaced. To do this, update the following /* three fields: * 1) body.action to 'replace' * 2) body.encoding to the encoding of the new data. * * Set to one of the following values: * * text - denotes that the generated body is in text format. * Lambda@Edge will propagate this as is. * base64 - denotes that the generated body is base64 encoded. * Lambda@Edge will base64 decode the data before sending * it to the origin. * 3) body.data to the new body. */ request.body.action = 'replace'; request.body.encoding = 'text'; request.body.data = getUpdatedBody(request); } callback(null, request); }; function getUpdatedBody(request) { /* HTTP body is always passed as base64-encoded string. Decode it. */ const body = Buffer.from(request.body.data, 'base64').toString(); /* HTML forms send data in query string format. Parse it. */ const params = querystring.parse(body); /* For demonstration purposes, we're adding one more param. * * You can put your custom logic here. For example, you can truncate long * bodies from malicious requests. */ params['new-param-name'] = 'new-param-value'; return querystring.stringify(params); }
- Python
-
import base64 from urllib.parse import parse_qs, urlencode def lambda_handler(event, context): request = event['Records'][0]['cf']['request'] if request['method'] == 'POST': ''' Request body is being replaced. To do this, update the following three fields: 1) body.action to 'replace' 2) body.encoding to the encoding of the new data. Set to one of the following values: text - denotes that the generated body is in text format. Lambda@Edge will propagate this as is. base64 - denotes that the generated body is base64 encoded. Lambda@Edge will base64 decode the data before sending it to the origin. 3) body.data to the new body. ''' request['body']['action'] = 'replace' request['body']['encoding'] = 'text' request['body']['data'] = getUpdatedBody(request) return request def getUpdatedBody(request): # HTTP body is always passed as base64-encoded string. Decode it body = base64.b64decode(request['body']['data']) # HTML forms send data in query string format. Parse it params = {k: v[0] for k, v in parse_qs(body).items()} # For demonstration purposes, we're adding one more param # You can put your custom logic here. For example, you can truncate long # bodies from malicious requests params['new-param-name'] = 'new-param-value' return urlencode(params)