Make spawn an option again

app/models/embedded_ansible_worker.rb

@@ -17,6 +17,7 @@ def start_runner
         Thread.exit
       end
     end
+    nil # return no pid
   end
 
   def kill

app/models/miq_worker.rb

@@ -335,6 +335,10 @@ def self.close_pg_sockets_inherited_from_parent
   end
 
   def start_runner
+    ENV['MIQ_SPAWN_WORKERS'] ? start_runner_via_spawn : start_runner_via_fork
+  end
+
+  def start_runner_via_fork
     self.class.before_fork
     pid = fork(:cow_friendly => true) do
       self.class.after_fork
@@ -346,6 +350,23 @@ def start_runner
     pid
   end
 
+  def self.build_command_line(guid)
+    command_line = "#{Gem.ruby} #{runner_script} --heartbeat --guid=#{guid} #{name}"
+    ENV['APPLIANCE'] ? "nice #{nice_increment} #{command_line}" : command_line
+  end
+
+  def self.runner_script
+    script = ManageIQ.root.join("lib/workers/bin/run_single_worker.rb")
+    raise "script not found: #{script}" unless File.exist?(script)
+    script
+  end
+
+  def start_runner_via_spawn
+    pid = Kernel.spawn(self.class.build_command_line(guid), :out => "/dev/null", :err => [Rails.root.join("log", "evm.log"), "a"])
+    Process.detach(pid)
+    pid
+  end
+
   def start
     self.pid = start_runner
     save

app/models/miq_worker/runner.rb

@@ -11,6 +11,7 @@ class TemporaryFailure < RuntimeError
 
   INTERRUPT_SIGNALS = ["SIGINT", "SIGTERM"]
 
+  # DELETE ME
   OPTIONS_PARSER_SETTINGS = [
     [:guid,       'EVM Worker GUID',       String],
   ]

lib/workers/bin/run_single_worker.rb

@@ -23,6 +23,10 @@
     options[:dry_run] = val
   end
 
+  opts.on("-g=GUID", "--guid=GUID", "Find an existing worker record instead of creating") do |val|
+    options[:guid] = val
+  end
+
   opts.on("-h", "--help", "Displays this help") do
     puts opts
     exit
@@ -52,7 +56,12 @@
 worker_class = worker_class.constantize
 worker_class.before_fork
 unless options[:dry_run]
-  worker = worker_class.create_worker_record
+  worker = if options[:guid]
+             worker_class.find_by!(:guid => options[:guid])
+           else
+             worker_class.create_worker_record
+           end
+
   begin
     worker.class::Runner.start_worker(:guid => worker.guid)
   ensure

spec/models/miq_worker_spec.rb

@@ -29,6 +29,32 @@ def all_workers
     expect(result.command_line).to eq "renice -n 5 -p 123"
   end
 
+  context ".build_command_line" do
+    before do
+      allow(MiqGenericWorker).to receive(:nice_increment).and_return("+10")
+    end
+
+    it "with ENV['APPLIANCE']" do
+      begin
+        old_env = ENV.delete('DATABASE_URL')
+        ENV['APPLIANCE'] = 'true'
+        w = FactoryGirl.build(:miq_generic_worker)
+        cmd = w.class.build_command_line(123)
+        expect(cmd).to start_with("nice +10")
+        expect(cmd).to end_with("MiqGenericWorker")
+      ensure
+        # ENV['x'] = nil deletes the key because ENV accepts only string values
+        ENV['APPLIANCE'] = old_env
+      end
+    end
+
+    it "without ENV['APPLIANCE']" do
+      w = FactoryGirl.build(:miq_generic_worker)
+      cmd = w.class.build_command_line(123)
+      expect(cmd).to_not start_with("nice +10")
+    end
+  end
+
   context ".has_required_role?" do
     def check_has_required_role(worker_role_names, expected_result)
       allow(described_class).to receive(:required_roles).and_return(worker_role_names)