Amazon S3 and Cloudfront with TTL=0 Testing procedure

Question

I Would like to test and see that my TTL=0 did work.
What I have:
S3 bucket that is mounted to directory in my redhat. so when I edit a simple txt file from the shell, I can open it in the aws console bucket manager and view the file. Also I have created cloudfront distribution so i can open the txt file from the cloudfront link.
Test:
I edit the txt file with the telnet, then open it from aws console on S3 bucket section, i see the file has changed, but when i open the file on the cloudfront link, it didnt change. This means the TTL=0 did not work.

How can i verify TTL=0 works ? and it is set correctly ? after creating the distribution i cannot find where to edit the TTL again.

Thanks

Answer 1

Quoting AWS :

Note that our default behavior isn't changing; if no cache control header is set, each edge location will continue to use an expiration period of 24 hours before checking the origin for changes to that file. You can also continue to use Amazon CloudFront's Invalidation feature to expire a file sooner than the TTL set on that file.

You're likely not setting the cache control correctly. One way to confirm that is to Enable S3 Bucket Logging - New files will appear whenever there are new HTTP GETs from your S3 Bucket, even if they come from CloudFront.

You could also test S3 Directly, with curl (or s3curl ) so you can track its headers correctly.

My recommendation is that, whenever you upload new content, you force CloudFront to Invalidate. If you're using tools like s3fs, then inotify/icron might help you

(Disclaimer: I totally hate the whole idea of mapping filesystems off to S3. They're quite different tools and you're likely to get 'leaky abstractions')

Answer 2

It is most likely that you are not sending any TTL headers from S3. CloudFront will look for a TTL header in the source file and if it doesn't find anything, will default to 24 hours.

You could look to set a bucket policy or use a tool like S3 browser to automatically set the headers. http://s3browser.com/automatically-apply-http-headers.php

If you just want to test then I would follow the steps below.

• Create a new text file in your bucket
• Through the AWS console, locate the file and check and/or add the caching headers
• Retrieve the file from CloudFront
• Change the file in the bucket
• Check the headers of the new file in AWS console (your S3 mapping utility may erase the previous file headers)
• Retrieve the new changed file from CloudFront

Sending an invalidate call to CloudFront with each request may become chargeable if you have a large number of edits a month. Plus invalidations take several minutes (sometimes 20mins or more) to propagate, meaning you could never instantly change your content.