Improve container alive detection

tasks/integration_local_spec.rb

@@ -37,12 +37,15 @@ def run
 
   def docker_run
     mount_dir = Pathname(__dir__).join('../').to_s
+    if container_alive?
+      raise "Docker container is already running. Please stop the container with `docker rm -f #{CONTAINER_NAME}`"
+    end
+
     Thread.new do
-      Thread.current.abort_on_exception = true
       sh 'docker', 'run', '--privileged', '--name', CONTAINER_NAME, '-v', "#{mount_dir}:/itamae", "ruby:#{@ruby_version}", 'sleep', '1d'
     end
-    
-    sleep 0.5 until `docker ps` =~ /itamae$/
+
+    sleep 0.5 until container_alive?
   end
 
   def prepare
@@ -76,4 +79,8 @@ def clean_docker_container
   def docker_exec(*cmd, options: [])
     sh 'docker', 'exec', '--env', 'LANG=en_US.utf8', *options, CONTAINER_NAME, *cmd
   end
+
+  def container_alive?
+    `docker ps` =~ /itamae$/
+  end
 end