问题
I have an Amazon EC2 Web Server instance which serves gzipped content when the Accept-Encoding header is set to gzip. But when I make the same request with the exact same header to a CloudFront CDN with the origin server as my Amazon EC2 instance, it doesn't send back a gzipped response.
I also tried creating a new CloudFront distribution(because I thought that the old distribution might have uncompressed response cached) and then making the same request and I still get an uncompressed response.
Can someone please tell me what I may be missing?
回答1:
This has been marked as a possible duplicate of a question relating to S3. The question is around EC2 - not S3, so I don't think this is a duplicate.
You’re likely seeing this issue due to Cloudfront adding a ‘Via’ header to the requests made to your origin server - it’s a know issue with IIS.
If you were to look at the incoming HTTP requests to your origin, you’d see something like this in your HTTP headers:
Via=1.1 9dc1db658f6cee1429b5ff20764c5b07.cloudfront.net (CloudFront)
X-Amz-Cf-Id=k7rFUA2mss4oJDdT7rA0HyjG_XV__XwBV14juZ8ZAQCrbfOrye438A==
X-Forwarded-For=121.125.239.19, 116.127.54.19
The addition of a ‘Via’ header is standard proxy server behaviour. When IIS sees this, it drops the gzip encryption (I’m guessing due to an assumption that older proxy servers couldn’t handle compressed content).
If you make the following changes to your applicationHost.config, you should rectify the issue:
<location path="Your Site">
<system.webServer>
<httpCompression noCompressionForHttp10="false" noCompressionForProxies="false" />
</system.webServer>
</location>
The other issue to watch out for is that IIS doesn’t always compress the first response it receives for a given resource, therefore, Cloudfront may make a request to the origin, receive, cache and then serve uncompressed version of the content to subsequent visitors. Again you can modify this behaviour using the serverRuntime settings in the applicationHost.config:
<location path="Your Site">
<system.webServer>
<httpCompression noCompressionForHttp10="false" noCompressionForProxies="false" />
<serverRuntime frequentHitThreshold="1" frequentHitTimePeriod="00:00:05" />
</system.webServer>
More details on these settings here: http://www.iis.net/configreference/system.webserver/serverruntime http://www.iis.net/configreference/system.webserver/httpcompression
Credit to this blog post for explaining the issue: http://codepolice.net/2012/06/26/problems-with-gzip-when-using-iis-7-5-as-an-origin-server-for-a-cdn/
来源：https://stackoverflow.com/questions/28217107/amazon-ec2-serves-gzipped-javascript-but-cloudfront-does-not-why