Enable a CDN for your Discourse

ufukayyildiz · May 8, 2021, 12:06pm

So files will not synchronise with my system, cloudfront just cache them. Am i true?

pfaffman · May 8, 2021, 12:48pm

Yes. That is correct. The CDN gets from your site just the assets that are requested of it.

Discourse will push to S3 static assets (like css and javascript) as well I uploads.

Pravi · June 25, 2021, 7:27pm

Is it possible to use cloudflare rules to cache static assets like css and javascript?

bartv · June 26, 2021, 6:23am

Yes, we use it that way and it works well. Just be very careful to disable any javascript optimizations. You can see our setup here:

Pravi · June 26, 2021, 7:16am

Thanks for the response.

I have already added the second and third rule but I didn’t get the first rule. What’s the need for 301 redirect??

bartv · June 26, 2021, 7:41am

You don’t need it; it’s in the description.

Pravi · June 26, 2021, 10:37am

Thanks for the response. What about the static assets like css and javascripts? Any rule possible for css and javascript??

bartv · June 26, 2021, 10:51am

I didn’t test that. I’m not sure that would work. At the very least you’d have to clear your Cloudflare cache after every rebuild.

Pravi · June 26, 2021, 1:35pm

It’s okay with me to clear the cache after every rebuild. What else would possibly go wrong if I make a rule to cache everything in https://myforum.com/assets/ ? Will this anyway affect user login? If you give a nod, I will test it for a week and report. I still have one unused rule.

MarcP · September 16, 2021, 2:40am

Just to clarify, is it correct we do not use this field (as well as CDN URL) if we are using cloudflare CDN?

I have setup cloudflare.template in app.yml as per docs.

Is any further config needed if using cloudflare?

Victor_Ashiedu · June 28, 2022, 1:33am

I just successfully used StackPath as CDN. Works as expected!

Canapin · July 26, 2022, 9:30am

Is it still the case nowadays?

From 2019:

It seems we have to be extra careful and that we lose some of Cloudflare benefits.

From 2020:

From 2021:

So, is Cloudflare reliable and efficient with Discourse today? Does disabling the “Rocket Loader” feature minimize the benefits?

I was thinking of moving from Stackpath to Bunny CDN, but the owner of my forum domain and former admin has a cloudflare enterprise account (he’s the owner of tinyURL btw) on which he could add the domain for free (Looking for a decrease in the forum fees in the future - #6 by Gilby - Forum Feedback - Unicyclist.com).

So, I wonder if it’s right, painless and effective to use Cloudflare instead of Bunny CDN.

Stephen · July 26, 2022, 11:01am

If you’re image-heavy then what you’ll spend increasing directly attached SSD will be far costlier than the equivalent S3 costs.

S3 does need a CDN in front of it to be cost effective as you’re billed on ingress and egress, but it’s still vastly cheaper than just slapping on more high speed SSD. CloudFlare can front S3, but asset caching is really the only feature you can use reliably. Putting CloudFlare between the client and the application server will also increase the number of hops and push application latency up. It’s no magic bullet.

Canapin · July 26, 2022, 11:45am

We’re not image-heavy. The goal of the CDN would be so the assets load fast to every user since our community is international (mainly US and Europe).

We use S3, but only to store backups.

Canapin · August 25, 2022, 4:38pm

Quick question. Is a rebake mandatory after we change our CDN? Or is it just if the CDN URL is different? Or is it not needed at all?

edit: or is it simply possible to replace the old URLs in the cooked posts by the new one with a rails script?

For example, if I have a post containing:

<img class="ytp-thumbnail-image"
src="https://f5i4i8k5.stackpathcdn.com/uploads/default/original/3X/f/3/f3bc5ab19cc0394f33fd008e90ca06e081886a0b.jpeg"
title="Riding a unicycle part 76: Sullivan Canyon - Los Angeles"
width="480"
height="360"
loading="lazy"
style="aspect-ratio: 480 / 360;">

Could I do a search & replace strings from f5i4i8k5.stackpathcdn.com to newcdn.unicyclist.com without breaking anything? It seems safe, but I want to be sure about what I do.

I don’t mind rebaking all my posts, but the problem I faced the first time is that I have thousands of embedded youtube videos, and my IP was blacklisted by Youtube during the rebake because of too many requests to youtube.

So, if there’s a safe alternative than rebake all the posts and face the same annoying issue, I’d prefer to go for the alternative…

pfaffman · August 26, 2022, 7:25am

There is a rake task that will do a replacement. I think they running that is safe and a good idea. Replace a string in all posts is what you’re looking for, I think.

Canapin · August 26, 2022, 9:52am

Hi Jay,

I’m not sure about using the rake task.

The CDN URLs seem to be present in the cooked fields rather than the raw fields (unless the message was sent by email).

From what I understand, post:remap search for the string in the raw field only.

github.com

discourse/discourse/blob/9db8f00b3dd6f2881adf1b786e29426889225e7a/lib/tasks/posts.rake#L173


      
            end
          
          
  puts
            puts "#{i} posts normalized!"
          end
          
          
def remap_posts(find, type, ignore_case, replace = "")
            ignore_case = ignore_case == 'true'
            i = 0
          
          
  Post.raw_match(find, type).find_each do |p|
              regex =
                case type
                when 'string' then
                  Regexp.new(Regexp.escape(find), ignore_case)
                when 'regex' then
                  Regexp.new(find, ignore_case)
                end
          
          
    new_raw = p.raw.gsub(regex, replace)

If replacing the CDN URLs in both the raw and cooked fields is safe, I guess I should go with a custom rails script?

pfaffman · August 26, 2022, 3:02pm

You’re right. There’s another . . . thing . . . that will replace a string in all fields in the database. That’s the one you’re looking for. Sorry but I can’t find it right now. There are some topics about moving from one s3, but there doesn’t seem to be a howto.

Canapin · August 26, 2022, 3:55pm

Thank you for this clue!

I guess it’s this?

DbHelper.remap('from', 'to')

Found on Rebaking old posts won't pull new S3 CDN URL after S3 bucket rename - #10 by Brad_Wood

And used here:

github.com

discourse/discourse/blob/1472e47aae5bfdfb6fd9abfe89beb186c751f514/lib/file_store/to_s3_migration.rb#L289


      
            raise failure_message
          elsif s3_objects.size + synced >= local_files.size
            log "Updating the URLs in the database..."
          
            from = "/uploads/#{@current_db}/original/"
            to = "#{SiteSetting.Upload.s3_base_url}/#{prefix}"
          
            if @dry_run
              log "REPLACING '#{from}' WITH '#{to}'"
            else
              DbHelper.remap(from, to, anchor_left: true)
            end
          
            [
              [
                "src=\"/uploads/#{@current_db}/original/(\\dX/(?:[a-f0-9]/)*[a-f0-9]{40}[a-z0-9\\.]*)",
                "src=\"#{SiteSetting.Upload.s3_base_url}/#{prefix}\\1"
              ],
              [
                "src='/uploads/#{@current_db}/original/(\\dX/(?:[a-f0-9]/)*[a-f0-9]{40}[a-z0-9\\.]*)",
                "src='#{SiteSetting.Upload.s3_base_url}/#{prefix}\\1"

If it’s a safe alternative to a rebake when changing our CDN service, a howto could be nice indeed.

pfaffman · August 26, 2022, 4:41pm

Oh hooray. Thanks for letting me know. I thought it would be enough for you to find it. Glad you got it.

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Enable a CDN for your Discourse

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