测试了一下使用API Gateway来触发Lambda应用,并将结果显示在网页上。
Lambda支持语言为: Node.js,Java,Python,C#,Go,PowerShell,等等。它具有无需管理服务器,根据需求自动扩展,便宜等优势。
具体流程
在S3 Bucket里存放网页,显示网页后,在网页里通过API Gateway来触发Lambda功能应用,并将Lambda功能应用返回的结果显示在网页上。Route53来使用DNS网址为可选。
创建Lambda应用
Lambda是EC2在一起的Compute界面下,点进去后,再点Create Function
来创建函数, 取名为:XiongLambdaFunction
,语言设置为Python 3.6,这样会自动生成以下代码:
import json
def lambda_handler(event, context):
# TODO implement
return {
'statusCode': 200,
'body': json.dumps('Hello from Lambda!')
}
进行以下替换:
import json
def lambda_handler(event, context):
print("In lambda handler")
resp = {
"statusCode": 200,
"headers": {
"Access-Control-Allow-Origin": "*",
},
"body": "Xiong Huilin"
}
return resp
创建API Gateway
创建一个API Gateway,在Networking & Content Delivery
下点API Gateway
,选择
REST
,API取名为:XiongTestAPI
,在Actions
下点Create Method
,选择GET
方法,Integration type选择Lambda Function
,并选择前面已经创建的XiongLambdaFunction
。点保存,有以下提示。
==You are about to give API Gateway permission to invoke your Lambda function:
arn:aws:lambda:ap-southeast-1:606255748358:function:XiongLambdaFunction==
点Deploy API
对API进行发布,发布成功后会有一个URL生成,这个生成的URL将会被用做第三步测试:
==Invoke URL: https://p9ciqi7imh.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI==
S3 Bucket网页测试触发API Gateway和Lambda函数
创建两个文件:Index.html和error.html,此测试是根据ACloud Guru所做的示例。
在index.html里,将GET请求的URL替换为: ==https://p9ciqi7imh.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI==,如下html代码所示:
<html>
<script>
function myFunction() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("my-demo").innerHTML = this.responseText;
}
};
xhttp.open("GET", "https://p9ciqi7imh.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI", true);
xhttp.send();
}
</script>
<body><div align="center"><br><br><br><br>
<h1>Hello <span id="my-demo">2nd December 2019!</span></h1>
<button onclick="myFunction()">Click me</button><br>
<img src="https://www.dropbox.com/s/2965glxbyqjmi9h/SanTi.jpg?raw=1"></div>
</body>
</html>
error.html
<html><body><h1>There has been an error for Xiong's website!</h1></body></html>
创建一个S3 Bucket,取名为: xionglambdatest
,在Properties
下面进行设置,Static website hosting
,创建了以下Endpoint, Index document
设置为index.html
,Error Document
设置为error.html
,保存。
==Static website hosting
Endpoint : http://xionglambdatest.s3-website-ap-southeast-1.amazonaws.com==
将前面创建的index.html
和error.html
进行上传,
如果你注册了域名的话,可以使用Route53来设置 A Record来指向S3 Bucket的Endpoint达到域名访问的目的。
这里直接测试:
==Static website hosting
Endpoint : http://xionglambdatest.s3-website-ap-southeast-1.amazonaws.com==
返回以下错误:
403 Forbidden
Code: AccessDenied
Message: Access Denied
RequestId: 0264A5A5BC4FBDE3
HostId: r03Yr+l5vDDiR/0YQL8if2qmRP1lBvBzLoeoGgw6z3jec8XnyWJsz790UwmZGI49ejY5QFYWrfE=
An Error Occurred While Attempting to Retrieve a Custom Error Document
Code: AccessDenied
Message: Access Denied
在S3 Bucket xionglambdatest
中,设置Make Public
,确认,再试,可以成功访问。
点按钮无反应,在Chrome的Develop Tool里发现碰到以下错误:
Access to XMLHttpRequest at
'https://byaaiuzpad.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI'
from origin 'http://xionglambdatest.s3-website-ap-southeast-1.amazonaws.com'
has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is
present on the requested resource.
CORS在作怪,在Resource
下里的Action
里点Enable CORS
,再试, 点按钮后,界面返回如下:
Hello {"statusCode": 200, "headers": {"Access-Control-Allow-Origin": "*"},
"body": "Xiong Huilin"}
说明https://p9ciqi7imh.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI
返回了{"statusCode": 200, "headers": {"Access-Control-Allow-Origin": "*"}, "body": "Xiong Huilin"}
。
重新再试,在创建GET
方法时,记得把Use Lambda Proxy integration
选择项选上, 表明是Lambda返回值 。另外记得在Resource
下里的Action
里点Enable CORS
, 最后Deploy API
。这次成功。
点按钮后,以下文字:
Hello 2nd December 2019!
变为:
Hello Xiong Huilin
。
也就是https://p9ciqi7imh.execute-api.ap-southeast-1.amazonaws.com/XiongReturnNameAPI
返回了Xiong Huilin
,测试成功!
点完按钮的效果如下:
碰到S3 Bucket删除问题
前面做Elastic Beanstalk测试的时候:AWS的CloudFormation和Elastic Beanstalk的简单测试,自动创建了名为elasticbeanstalk-ap-southeast-1-606255748358
的S3 Bucket,删除时返回了Access Denied
的错误。
参见: AWS Forum: can’t delete empty elasticbeanstalk created bucket
在以下Bucket Policy的JSON文件里将Deny
改成Allow
,就可以删除了,问题解决。
{
"Sid": "eb-58950a8c-feb6-11e2-89e0-0800277d041b",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": "s3:DeleteBucket",
"Resource": "arn:aws:s3:::elasticbeanstalk-ap-southeast-1-606255748358"
}
参见Bucket Policy Examples,可以使用以下JSON文件设置Bucket Policy
以达到Bucket为公共访问的目的:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "PublicRead",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::xionglambdatest/*"
}
]
}
术语
==Lambda==:参见什么是 AWS Lambda?
==REST==:参见Representational_state_transfer 维基
Reference
Lambda Troubleshooting – Acloudguru
什么是 AWS Lambda?
Representational_state_transfer 维基
AWS的CloudFormation和Elastic Beanstalk的简单测试
AWS Forum: can’t delete empty elasticbeanstalk created bucket
ACloud Guru
Bucket Policy Examples