Hi,
We all know that cloudflare compress content when it deliver to user. Sometime BR sometime GZIP. But it never send Vary: Accept-Encoding header.
Why?
sdayman,
You must be using gzip/mod_deflate at origin. My question is purely related to cloudflare. If cloudflare is compressing a content(origin is not compressing), why it is not adding vary accept-encoding.
Is there a private msg kind of thing in CF community. I would love to share the link.
Yeah, each of my sites send the Response Header Vary: Origin, Accept-Encoding.
see https://support.cloudflare.com/hc/en-us/articles/200168086-Does-Cloudflare-compress-resources- and it’s only for certain mime types https://support.cloudflare.com/hc/en-us/articles/200168396
Does Cloudflare compress resources?
Yes, Cloudflare applies gzip and brotli compression to some types of content. We also gzip items based on the browser’s useragent to help speed up page loading time.
If you’re already using gzip we will honor your gzip settings as long as you’re passing the details in a header from your web server for the files.
It can be dependent on your origin web server headers.
eva200,
As I told in 1st post that I know cloudflare compress certain MIME types. My Question is if we do not compress at our origin and only depend cloudflare to compress MIME, why cloudflare do not send vary accept-encoding.
Wouldn’t know exactly as I’ve never not setup gzip compression on origin - it’s basically must have for performance even if CF is front of it. Any reason why you’re not doing gzip compression or at least supporting it at the origin web server level ?
Cloudflare do not support brotli at origin. They only ask gzip/deflate content from origin. Now they ask for gzip content from origin and than convert it to brotli for the browser which support it. Dont you think it will take huge time?
Plus the rule should be whosoever compress should present accept encoding.
I haven’t noticed a difference when I had my origin with gzip disabled versus gzip enabled behind Cloudflare - especially as static files will be cached by default so it’s only a cache miss/bypass that hits the origin anyway. My Wordpress blog https://servermanager.guide/ is just as fast with gzip enabled on the origin as it was with gzip disabled at origin 
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Can you share how do u gzip at origin? if it is possible for you to share.
I use my own Centmin Mod LEMP stack’s Nginx 1.17 mainline builds. But for any Nginx server it’s outlined at Compression and Decompression | NGINX Plus
For Apache 2.4 mod_deflate - Apache HTTP Server Version 2.4
Just search for guides on nginx or apache 2.4 gzip compression i.e. How to Enable Gzip Compression in Apache Web Server - TecAdmin
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I used this method on server. It always set accept-encoding header. But if I dont used mod_deflate at server, cloudflare never set vary, that is my question.
<IfModule mod_deflate.c>
DeflateFilterNote ratio
DeflateCompressionLevel 9
DeflateMemLevel 9
DeflateWindowSize 15
# Compress HTML, CSS, JavaScript, Text, XML and fonts
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/richtext
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/x-script
AddOutputFilterByType DEFLATE text/x-component
AddOutputFilterByType DEFLATE text/x-java-source
AddOutputFilterByType DEFLATE text/x-markdown
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/js
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE application/x-perl
AddOutputFilterByType DEFLATE application/x-httpd-cgi
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xml+rss
AddOutputFilterByType DEFLATE application/json
AddOutputFilterByType DEFLATE multipart/bag
AddOutputFilterByType DEFLATE multipart/mixed
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/x-woff
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/ttf
AddOutputFilterByType DEFLATE application/x-ttf
AddOutputFilterByType DEFLATE application/otf
AddOutputFilterByType DEFLATE application/x-otf
AddOutputFilterByType DEFLATE application/truetype
AddOutputFilterByType DEFLATE application/opentype
AddOutputFilterByType DEFLATE application/x-opentype
AddOutputFilterByType DEFLATE application/font-woff
AddOutputFilterByType DEFLATE application/eot
AddOutputFilterByType DEFLATE application/font
AddOutputFilterByType DEFLATE application/font-sfnt
AddOutputFilterByType DEFLATE application/wasm
</IfModule>see How to Fix "Specify a Vary: Accept-Encoding Header" Warning
apache
<IfModule mod_headers.c>
<FilesMatch ".(js|css|xml|gz|html)$">
Header append Vary: Accept-Encoding
</FilesMatch>
</IfModule>
nginx
gzip_vary on;
that is why you aren’t seeing vary accept-encoding headers as your Apache server isn’t configured for it I assume.
eva2000,
I do not think you are getting my question correctly. If I setup mod_deflate at origin. My origin set vary: Accept-encoding correctly. So for accept encoding to work I have to setup mod_deflate at origin server.
Now if I DO NOT want to set mod_deflate at server. Cloudflare gets content NOT COMPRESSED. But after doing performance tweaking it send that content to user COMPRESS(gzip/brotli). But do not send Vary header why?
If anyone compress content it should send accept encoding.
Note - > one do not see to set header for vary at apache. If any one set mod_deflate correctly it is automatically added.
got an example of curl header outputs for a static file request i.e. js or css file with Cloudflare versus without Cloudflare proxied ?
curl -sI https://yourdomain.com
and
curl -sI -H 'Accept-Encoding: gzip' https://yourdomain.com
Or if curl access isn’t available, use HTTP Header Checker - Check HTTP Response Headers With curl | KeyCDN Tools
If needed just change your domain name for a dummy domain name.
If you have a web app or something else managing your headers i.e. wordpress cache/optimisation plugins, they may also be mangling your headers served.
I haven’t used Apache in years though. I know for Nginx it works.
1 Like
Thank you for solving misery of my life. That 1 thing is bothering me for years. If browser send request with accept encoding cloudflare do send vary header. If browser not requesting for gzip content it send nozip content automatically. That way it maintain more compatibility with more browsers.
Thanks a lot again.
Proper operation is that vary accept-encoding header should sent for either compressed or non-compressed requests though and generally that should be case with Cloudflare too. If not I’d open up a Cloudflare support ticket and see if it’s a bug on CF end and/or origin config issue too.
And well most browsers would be sending the gzip compressed request.
Output from curl checks above would also help CF support in the ticket you submit.
eva2000
Now I get why cloudflare do it. If browser send Accept-encoding:gzip. cloudflare will return vary header. If it doesn’t cloudflare will send uncompressed data for older browser.
It is not a bug just a compatibility reason. Thanks again.
older browsers ? which browser/version you testing with ?
I have seen many browser, especially from MEA, SEA region which do not support gzip content. (Older mobiles).
E.G. Samsung internet browser older versions.