before_x middleware seems to be triggering twice

[drum445]

When using before_all (which I am currently using for auth checks), I noticed my DB calls were duplicating. I checked into this and the cause seems to be these middleware filters are firing twice.

Example:

require "kemal"

before_all do |env|
  puts "RUNNING THIS FOR #{env.request.path}; #{env.object_id}"
end

get "/" do |env|
  "hello, home"
end

get "/about" do |env|
  "hello, about"
end

Kemal.run

Output:

RUNNING THIS FOR /; 131141490140544
RUNNING THIS FOR /; 131141490140544
2026-06-06T11:50:46.948687Z   INFO - kemal: 200 GET / 3.32ms
RUNNING THIS FOR /about; 131141490139392
RUNNING THIS FOR /about; 131141490139392
2026-06-06T11:50:48.969343Z   INFO - kemal: 200 GET /about 3.44ms

I've tried swapping the order of route declarations and before_all, but the same result happens.

What does seem to work is using this instead, but I'm unsure about why this would cause the difference:

before_all "/*" do |env|
  puts "RUNNING THIS FOR #{env.request.path}; #{env.object_id}"
end

But the issue now is this doesn't trigger for "/"

Thanks!

[drum445]

After a lot of debugging, I think the main issue with my project is this (after changing before_all to before all "/*"):

before_all "/api/*" do |env|
  env.response.content_type = "application/json"
end

If I have the above combined with before_all "/*" do |env| , then requests to "/" don't trigger the "/*" filter.
If I change the /api/* to an after_all then it does.

Seems there's some strange behaviour going on with these filters

[sdogruyol]

Thanks for the repro, this looks like a real bug.

I traced it back to #737. before_all registers on path *, and call_block_for_path_type runs wildcard filters first, then does a radix lookup for the actual path. For / that lookup still hits the same * filter, so it runs twice on the same context. That matches what you're seeing with the duplicate env.object_id.

The before_all "/" workaround makes sense too. It avoids the double run because / isn't matched the same way, but / doesn't match /* in the radix tree, so the root path gets skipped.

I think the fix is to skip wildcard matches on the second lookup if they already ran in the explicit wildcard step. I can put together a PR with a spec if that helps.

[drum445]

Yeah, if you could please. As before_all "/*" do |env| does run on "/", providing there isn't two of them.

For example I currently have this setup and it is working properly,

before_all "/*" do |env|
  next if static_files?(env)
  # Auth middleware logic here.
end

after_all "/api/*" do |env|
  env.response.content_type = "application/json"
end

But if I change the after_all to before_all, then "/" doesn't trigger the auth middleware filter.

[sdogruyol]

Please check #758

[drum445]

@sdogruyol thanks mate, that PR looks like it'll solve it. While this issue is raised I think I've spotted another issue with after_all.

When I have this

after_all "/api/*" do |env|
  env.response.content_type = "application/json"
end

If a /api/ route is returning a large payload, every response logs an error:

Jun 09 23:02:50 ubuntu-s-1vcpu-1gb-lon1-01 landing[2792658]: Headers already sent (IO::Error)

I tracked it down to an issue with after_all, so when removing that filter I no longer get that error.

I can try and build a replication example if needed

[sdogruyol]

@drum445 please do share a repro and I'll look into it. Could you please open another issue for that

[Sija]

Perhaps #737 should be reverted and redone properly?

[drum445]

@sdogruyol, can't share the repo, but I've replicated it in a single file example and raised an issue here: #759