incompatible with sinatra 4.0 / rack 3.0

[namiwang]

After upgrading sinatra (which jekyll-admin depends on) to 4.0, got the following error when staring server

bundler: failed to load command: jekyll (/Users/nami/.asdf/installs/ruby/3.2.2/bin/jekyll)
<internal:/Users/nami/.asdf/installs/ruby/3.2.2/lib/ruby/site_ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require': cannot load such file -- rack/handler (LoadError)
	from <internal:/Users/nami/.asdf/installs/ruby/3.2.2/lib/ruby/site_ruby/3.2.0/rubygems/core_ext/kernel_require.rb>:37:in `require'
	from /Users/nami/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/jekyll-admin-0.11.1/lib/jekyll/commands/serve.rb:23:in `jekyll_admin_monkey_patch'
	from /Users/nami/.asdf/installs/ruby/3.2.2/lib/ruby/gems/3.2.0/gems/jekyll-admin-0.11.1/lib/jekyll/commands/serve.rb:15:in `start_up_webrick'
...

The root cause is sinatra 4 dropped support for rack 2

refs:

• sinatra 4.0 changelog
• rack 3 upgrade guide

A workaround is to add gem "rackup" to Gemfile.

A simple fix would be limiting spec.add_dependency "sinatra", ">= 1.4", "< 4.0" in gemspec, or adding rackup as a direct dependency.

[kebugcheckex]

Github Dependabot sent me multiple security alerts regarding rack version used in jekyll-admin. rack should be upgraded to at least 2.2.8.1. Upgrading sinatra to 4 will solve the problem.

[yuanworks]

@namiwang unfortunately your fix (adding rackup gem) doesn't let me save new pages inside the admin because of the following error:

 NoMethodError - undefined method `rewind' for #<Rackup::Handler::WEBrick::Input

I managed to get both admin and saving files working by downgrading sinatra:

gem "sinatra", ">= 3", "< 4"

Edit: issue mentioned here too #709

[philosophicles]

I've had similar but not identical issues today after forking from an old jekyll theme, switching on dependabot, and it asking for some massive version leaps in both rack and jekyll-admin.

jekyll 3.9.5 | Error:  uninitialized constant Rack::Handler
/usr/local/lib/ruby/gems/3.3.0/gems/jekyll-admin-0.11.1/lib/jekyll/commands/serve.rb:23:in `jekyll_admin_monkey_patch': uninitialized constant Rack::Handler (NameError)

          @server.mount "/admin", Rack::Handler::WEBrick, JekyllAdmin::StaticServer
                                      ^^^^^^^^^
	from /usr/local/lib/ruby/gems/3.3.0/gems/jekyll-admin-0.11.1/lib/jekyll/commands/serve.rb:15:in `start_up_webrick'
	from /usr/local/lib/ruby/gems/3.3.0/gems/jekyll-3.9.5/lib/jekyll/commands/serve.rb:104:in `process'
...

Thanks @yuanworks : after trying various other fix suggestions from around the internet, downgrading sinatra to 3.x (3.2.0 specifically) did the trick for me.

I am not normally a ruby person and a little lost in this dependency mire, but commenting in case this helps anyone else out.

[pboling]

Here's the answer (most likely).

You need to add the rackup gem to your dependencies in order to be compatible with rack v3.

gem "rackup"

[pboling]

@yuanworks You would also need to replace your line that looks like this:

Rack::Handler::WEBrick.run server

with a line that looks like this:

Rackup::Server.start app: server

where server is something like:

server = Rack::Builder.new do 
  # ...
end

Note: it will still run WEBrick.

[bishisht]

gem "sinatra", ">= 3", "< 4"

This worked for me thank you. @philosophicles