通过AWS API网关和Lambda函数返回动态内容类型

Question

我错过了什么，为什么这看起来这么难？

Answer 1

结果发现API网关不是问题所在。我的Lambda函数没有返回正确的头。

为了处理二进制响应，我发现您需要将二进制支持内容类型设置为*/*（也就是所有内容），然后让Lambda函数返回属性isbase64encode设置为true。被base64编码并指示的响应将被解码并作为二进制处理，而其他请求将原样返回。

下面是Lambda函数的一个简单要点，该函数采用给定路径，从S3读取文件并通过API网关返回：

/**
 * This is a simple AWS Lambda function that will look for a given file on S3 and return it
 * passing along all of the headers of the S3 file. To make this available via a URL use
 * API Gateway with an AWS Lambda Proxy Integration.
 * 
 * Set the S3_REGION and S3_BUCKET global parameters in AWS Lambda
 * Make sure the Lambda function is passed an object with `{ pathParameters : { proxy: 'path/to/file.jpg' } }` set
 */

var AWS = require('aws-sdk');

exports.handler = function( event, context, callback ) {
    var region = process.env.S3_REGION;
    var bucket = process.env.S3_BUCKET;
    var key = decodeURI( event.pathParameters.proxy );

    // Basic server response
    /*
    var response = {
        statusCode: 200,
        headers: {
            'Content-Type': 'text/plain',
        },
        body: "Hello world!",
    };
    callback( null, response );
    */

    // Fetch from S3
    var s3 = new AWS.S3( Object.assign({ region: region }) );
    return s3.makeUnauthenticatedRequest(
        'getObject',
        { Bucket: bucket, Key: key },
        function(err, data) {
            if (err) {
                return err;
            }

            var isBase64Encoded = false;
            if ( data.ContentType.indexOf('image/') > -1 ) {
                isBase64Encoded = true;
            }

            var encoding = '';
            if ( isBase64Encoded ) {
                encoding = 'base64'
            }
            var resp = {
                statusCode: 200,
                headers: {
                    'Content-Type': data.ContentType,
                },
                body: new Buffer(data.Body).toString(encoding),
                isBase64Encoded: isBase64Encoded
            };

            callback(null, resp);
        }
    );
};