DEV: Add compatibility with Pitchfork (#293)

This patch introduces a web server adapter for the upgrader class. This
allows the upgrader to work with both Unicorn and Pitchfork.

The user experience when watching the upgrade process from the admin page
should stay the same.

Author: Flink

lib/docker_manager/pitchfork_adapter.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module DockerManager
+  class PitchforkAdapter < WebServerAdapter
+    def server_name
+      "Pitchfork"
+    end
+
+    def launcher_pid
+      `pgrep -f unicorn_launcher`.strip.to_i
+    end
+
+    def master_pid
+      `pgrep -f "pitchfork monitor"`.strip.to_i
+    end
+  end
+end

lib/docker_manager/unicorn_adapter.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module DockerManager
+  class UnicornAdapter < WebServerAdapter
+    def server_name
+      "Unicorn"
+    end
+
+    def launcher_pid
+      `pgrep -f unicorn_launcher`.strip.to_i
+    end
+
+    def master_pid
+      `pgrep -f "unicorn master -E"`.strip.to_i
+    end
+  end
+end

lib/docker_manager/upgrader.rb

@@ -1,11 +1,20 @@
 # frozen_string_literal: true
 
+require_relative "web_server_adapter"
+require_relative "unicorn_adapter"
+require_relative "pitchfork_adapter"
+
 class DockerManager::Upgrader
+  attr_reader :web_server
+
+  delegate :min_workers, :server_name, :launcher_pid, :master_pid, :workers, to: :web_server
+
   def initialize(user_id, repos, from_version)
     @user_id = user_id
     @user = User.find(user_id)
     @repos = repos.is_a?(Array) ? repos : [repos]
     @from_version = from_version
+    @web_server = web_server_adapter
   end
 
   def reset!
@@ -15,10 +24,6 @@ def reset!
     status(nil)
   end
 
-  def min_workers
-    1
-  end
-
   def upgrade
     return if @repos.any? { |repo| !repo.start_upgrading }
 
@@ -31,40 +36,28 @@ def upgrade
     log("*** Please be patient, next steps might take a while ***")
     log("********************************************************")
 
-    launcher_pid = unicorn_launcher_pid
-    master_pid = unicorn_master_pid
-    workers = unicorn_workers(master_pid).size
-
-    if workers < 2
-      log("ABORTING, you do not have enough unicorn workers running")
+    if workers.size <= min_workers
+      log("ABORTING, you do not have enough #{server_name} workers running")
       raise "Not enough workers"
     end
 
     if launcher_pid <= 0 || master_pid <= 0
-      log("ABORTING, missing unicorn launcher or unicorn master")
-      raise "No unicorn master or launcher"
+      log("ABORTING, missing #{server_name} launcher or master/monitor")
+      raise "No #{server_name} master or launcher"
     end
 
     percent(5)
 
-    log("Cycling Unicorn, to free up memory")
-    reload_unicorn(launcher_pid)
+    log("Cycling #{server_name}, to free up memory")
+    web_server.reload
 
     percent(10)
     reloaded = false
-    num_workers_spun_down = workers - min_workers
+    num_workers_spun_down = workers.size - min_workers
 
     if num_workers_spun_down.positive?
-      log "Stopping #{workers - min_workers} Unicorn worker(s), to free up memory"
-      num_workers_spun_down.times { Process.kill("TTOU", unicorn_master_pid) }
-    end
-
-    if ENV["UNICORN_SIDEKIQS"].to_i > 0
-      log "Stopping job queue to reclaim memory, master pid is #{master_pid}"
-      Process.kill("TSTP", unicorn_master_pid)
-      sleep 1
-      # older versions do not have support, so quickly send a cont so master process is not hung
-      Process.kill("CONT", unicorn_master_pid)
+      log "Stopping #{num_workers_spun_down} #{server_name} worker(s), to free up memory"
+      web_server.scale_down_workers(num_workers_spun_down)
     end
 
     # HEAD@{upstream} is just a fancy way how to say origin/main (in normal case)
@@ -117,7 +110,7 @@ def upgrade
     run("bundle exec rake s3:upload_assets") if using_s3_assets
 
     percent(80)
-    reload_unicorn(launcher_pid)
+    web_server.reload
     reloaded = true
 
     # Flush nginx cache here - this is not critical, and the rake task may not exist yet - ignore failures here.
@@ -147,13 +140,14 @@ def upgrade
     end
 
     if num_workers_spun_down.to_i.positive? && !reloaded
-      log "Spinning up #{num_workers_spun_down} Unicorn worker(s) that were stopped initially"
-      num_workers_spun_down.times { Process.kill("TTIN", unicorn_master_pid) }
+      log "Spinning up #{num_workers_spun_down} #{server_name} worker(s) that were stopped initially"
+      web_server.scale_up_workers(num_workers_spun_down)
     end
 
     raise ex
   ensure
     @repos.each(&:stop_upgrading)
+    web_server.clear_restart_flag
   end
 
   def publish(type, value)
@@ -269,47 +263,11 @@ def log_version_upgrade
 
   private
 
-  def pid_exists?(pid)
-    Process.getpgid(pid)
-  rescue Errno::ESRCH
-    false
-  end
-
-  def unicorn_launcher_pid
-    `ps aux | grep unicorn_launcher | grep -v sudo | grep -v grep | awk '{ print $2 }'`.strip.to_i
-  end
-
-  def unicorn_master_pid
-    `ps aux | grep "unicorn master -E" | grep -v "grep" | awk '{print $2}'`.strip.to_i
-  end
-
-  def unicorn_workers(master_pid)
-    `ps -f --ppid #{master_pid} | grep worker | awk '{ print $2 }'`.split("\n").map(&:to_i)
-  end
-
-  def local_web_url
-    "http://127.0.0.1:#{ENV["UNICORN_PORT"] || 3000}/srv/status"
-  end
-
-  def reload_unicorn(launcher_pid)
-    log("Restarting unicorn pid: #{launcher_pid}")
-    original_master_pid = unicorn_master_pid
-    Process.kill("USR2", launcher_pid)
-
-    iterations = 0
-    while pid_exists?(original_master_pid)
-      iterations += 1
-      break if iterations >= 60
-      log("Waiting for Unicorn to reload#{"." * iterations}")
-      sleep 2
-    end
-
-    iterations = 0
-    while `curl -s #{local_web_url}` != "ok"
-      iterations += 1
-      break if iterations >= 60
-      log("Waiting for Unicorn workers to start up#{"." * iterations}")
-      sleep 2
-    end
+  def web_server_adapter
+    if `pgrep -f '^unicorn[^_]'`.present?
+      DockerManager::UnicornAdapter
+    else
+      DockerManager::PitchforkAdapter
+    end.new(self)
   end
 end

lib/docker_manager/web_server_adapter.rb

@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+module DockerManager
+  class WebServerAdapter
+    RESTART_FLAG_KEY = "docker_manager:upgrade:server_restarting"
+
+    attr_reader :upgrader
+
+    delegate :log, to: :upgrader
+
+    def initialize(upgrader)
+      @upgrader = upgrader
+    end
+
+    def workers
+      `pgrep -f -P #{master_pid} worker`.split("\n").map(&:to_i)
+    end
+
+    def local_web_url
+      "http://127.0.0.1:#{ENV["UNICORN_PORT"] || 3000}/srv/status"
+    end
+
+    def scale_down_workers(count)
+      count.times { Process.kill("TTOU", master_pid) }
+    end
+
+    def scale_up_workers(count)
+      count.times { Process.kill("TTIN", master_pid) }
+    end
+
+    def min_workers
+      1
+    end
+
+    def reload
+      set_restart_flag
+      log("Restarting #{server_name} pid: #{launcher_pid}")
+      original_master_pid = master_pid
+      Process.kill("USR2", launcher_pid)
+
+      # Wait for the original master/monitor to exit (it will spawn a new one)
+      iterations = 0
+      while pid_exists?(original_master_pid)
+        iterations += 1
+        break if iterations >= 60
+        log("Waiting for #{server_name} to reload#{"." * iterations}")
+        sleep 2
+      end
+
+      # Wait for workers to be ready
+      iterations = 0
+      while `curl -s #{local_web_url}` != "ok"
+        iterations += 1
+        break if iterations >= 60
+        log("Waiting for #{server_name} workers to start up#{"." * iterations}")
+        sleep 2
+      end
+      clear_restart_flag
+    end
+
+    def set_restart_flag
+      Discourse.redis.setex(RESTART_FLAG_KEY, 2.minutes.to_i, 1)
+    end
+
+    def clear_restart_flag
+      Discourse.redis.del(RESTART_FLAG_KEY)
+    end
+
+    private
+
+    def pid_exists?(pid)
+      Process.getpgid(pid)
+    rescue Errno::ESRCH
+      false
+    end
+  end
+end

spec/lib/docker_manager/pitchfork_adapter_spec.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require "docker_manager/upgrader"
+
+RSpec.describe DockerManager::PitchforkAdapter do
+  subject(:adapter) { described_class.new(upgrader) }
+
+  let(:upgrader) { instance_double(DockerManager::Upgrader, log: nil) }
+
+  before { allow_any_instance_of(Kernel).to receive(:`) }
+
+  it_behaves_like "a web server adapter"
+
+  describe "#server_name" do
+    it "returns 'Pitchfork'" do
+      expect(adapter.server_name).to eq("Pitchfork")
+    end
+  end
+
+  describe "#launcher_pid" do
+    before do
+      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f unicorn_launcher").and_return(
+        "1234\n",
+      )
+    end
+
+    it "returns the pid of the 'unicorn_launcher' process" do
+      expect(adapter.launcher_pid).to eq(1234)
+    end
+  end
+
+  describe "#master_pid" do
+    before do
+      allow_any_instance_of(Kernel).to receive(:`).with('pgrep -f "pitchfork monitor"').and_return(
+        "5678\n",
+      )
+    end
+
+    it "returns the pid of the Pitchfork monitor process" do
+      expect(adapter.master_pid).to eq(5678)
+    end
+  end
+end

spec/lib/docker_manager/unicorn_adapter_spec.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require "docker_manager/upgrader"
+
+RSpec.describe DockerManager::UnicornAdapter do
+  subject(:adapter) { described_class.new(upgrader) }
+
+  let(:upgrader) { instance_double(DockerManager::Upgrader, log: nil) }
+
+  before { allow_any_instance_of(Kernel).to receive(:`) }
+
+  it_behaves_like "a web server adapter"
+
+  describe "#server_name" do
+    it "returns 'Unicorn'" do
+      expect(adapter.server_name).to eq("Unicorn")
+    end
+  end
+
+  describe "#launcher_pid" do
+    before do
+      allow_any_instance_of(Kernel).to receive(:`).with("pgrep -f unicorn_launcher").and_return(
+        "1234\n",
+      )
+    end
+
+    it "returns the pid of the 'unicorn_launcher' process" do
+      expect(adapter.launcher_pid).to eq(1234)
+    end
+  end
+
+  describe "#master_pid" do
+    before do
+      allow_any_instance_of(Kernel).to receive(:`).with('pgrep -f "unicorn master -E"').and_return(
+        "5678\n",
+      )
+    end
+
+    it "returns the pid of the Unicorn master process" do
+      expect(adapter.master_pid).to eq(5678)
+    end
+  end
+end