diff --git a/config/initializers/cluster_events_before_phased_restart.rb b/config/initializers/cluster_events_before_phased_restart.rb
index d029adbe3634ad86eed533db1897aa0c52d9ea80..f84682c1436658b5f8d1bd2332f7b3331cc0d557 100644
--- a/config/initializers/cluster_events_before_phased_restart.rb
+++ b/config/initializers/cluster_events_before_phased_restart.rb
@@ -7,8 +7,6 @@
 #
 # Follow-up the issue: https://gitlab.com/gitlab-org/gitlab/issues/34107
 
-if Gitlab::Runtime.puma?
-  Puma::Cluster.prepend(::Gitlab::Cluster::Mixins::PumaCluster)
-elsif Gitlab::Runtime.unicorn?
-  Unicorn::HttpServer.prepend(::Gitlab::Cluster::Mixins::UnicornHttpServer)
-end
+return unless Gitlab::Runtime.puma?
+
+Puma::Cluster.prepend(::Gitlab::Cluster::Mixins::PumaCluster)
diff --git a/lib/gitlab/cluster/mixins/unicorn_http_server.rb b/lib/gitlab/cluster/mixins/unicorn_http_server.rb
deleted file mode 100644
index 440ed02a3557f5986fefab5f9ddfd0dbded59563..0000000000000000000000000000000000000000
--- a/lib/gitlab/cluster/mixins/unicorn_http_server.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-# frozen_string_literal: true
-
-module Gitlab
-  module Cluster
-    module Mixins
-      module UnicornHttpServer
-        def self.prepended(base)
-          unless base.method_defined?(:reexec) && base.method_defined?(:stop)
-            raise 'missing method Unicorn::HttpServer#reexec or Unicorn::HttpServer#stop'
-          end
-        end
-
-        def reexec
-          Gitlab::Cluster::LifecycleEvents.do_before_graceful_shutdown
-
-          super
-        end
-
-        # The stop on non-graceful shutdown is executed twice:
-        # `#stop(false)` and `#stop`.
-        #
-        # The first stop will wipe-out all workers, so we need to check
-        # the flag and a list of workers
-        def stop(graceful = true)
-          if graceful && @workers.any? # rubocop:disable Gitlab/ModuleWithInstanceVariables
-            Gitlab::Cluster::LifecycleEvents.do_before_graceful_shutdown
-          end
-
-          super
-        end
-      end
-    end
-  end
-end
diff --git a/spec/lib/gitlab/cluster/mixins/unicorn_http_server_spec.rb b/spec/lib/gitlab/cluster/mixins/unicorn_http_server_spec.rb
deleted file mode 100644
index 7f7c95b252710d90febeabf2573da55a5c519f21..0000000000000000000000000000000000000000
--- a/spec/lib/gitlab/cluster/mixins/unicorn_http_server_spec.rb
+++ /dev/null
@@ -1,117 +0,0 @@
-# frozen_string_literal: true
-
-require 'spec_helper'
-
-# For easier debugging set `UNICORN_DEBUG=1`
-
-RSpec.describe Gitlab::Cluster::Mixins::UnicornHttpServer do
-  before do
-    stub_const('UNICORN_STARTUP_TIMEOUT', 30)
-  end
-
-  context 'when running Unicorn' do
-    using RSpec::Parameterized::TableSyntax
-
-    where(:signal, :exitstatus, :termsig) do
-      # executes phased restart block
-      :USR2 | 140 | nil
-      :QUIT | 140 | nil
-
-      # does not execute phased restart block
-      :INT | 0 | nil
-      :TERM | 0 | nil
-    end
-
-    with_them do
-      it 'properly handles process lifecycle' do
-        with_unicorn(workers: 1) do |pid|
-          Process.kill(signal, pid)
-
-          child_pid, child_status = Process.wait2(pid)
-          expect(child_pid).to eq(pid)
-          expect(child_status.exitstatus).to eq(exitstatus)
-          expect(child_status.termsig).to eq(termsig)
-        end
-      end
-    end
-  end
-
-  private
-
-  def with_unicorn(workers:, timeout: UNICORN_STARTUP_TIMEOUT)
-    with_unicorn_configs(workers: workers) do |unicorn_rb, config_ru|
-      cmdline = [
-        "bundle", "exec", "unicorn",
-        "-I", Rails.root.to_s,
-        "-c", unicorn_rb,
-        config_ru
-      ]
-
-      IO.popen(cmdline) do |process|
-        # wait for process to start:
-        # I, [2019-10-15T13:21:27.565225 #3089]  INFO -- : master process ready
-        wait_for_output(process, /master process ready/, timeout: timeout)
-        consume_output(process)
-
-        yield(process.pid)
-      ensure
-        begin
-          Process.kill(:KILL, process.pid)
-        rescue Errno::ESRCH
-        end
-      end
-    end
-  end
-
-  def with_unicorn_configs(workers:)
-    Dir.mktmpdir do |dir|
-      File.write "#{dir}/unicorn.rb", <<-EOF
-        require './lib/gitlab/cluster/lifecycle_events'
-        require './lib/gitlab/cluster/mixins/unicorn_http_server'
-
-        worker_processes #{workers}
-        listen "127.0.0.1:0"
-        preload_app true
-
-        Unicorn::HttpServer.prepend(#{described_class})
-
-        mutex = Mutex.new
-
-        Gitlab::Cluster::LifecycleEvents.on_before_blackout_period do
-          mutex.synchronize do
-            exit(140)
-          end
-        end
-
-        # redirect stderr to stdout
-        $stderr.reopen($stdout)
-      EOF
-
-      File.write "#{dir}/config.ru", <<-EOF
-        run -> (env) { [404, {}, ['']] }
-      EOF
-
-      yield("#{dir}/unicorn.rb", "#{dir}/config.ru")
-    end
-  end
-
-  def wait_for_output(process, output, timeout:)
-    Timeout.timeout(timeout) do
-      loop do
-        line = process.readline
-        puts "UNICORN_DEBUG: #{line}" if ENV['UNICORN_DEBUG']
-        break if line =~ output
-      end
-    end
-  end
-
-  def consume_output(process)
-    Thread.new do
-      loop do
-        line = process.readline
-        puts "UNICORN_DEBUG: #{line}" if ENV['UNICORN_DEBUG']
-      end
-    rescue StandardError
-    end
-  end
-end