Add healthcheck before deploy

lib/mrsk/commands/app.rb

@@ -75,10 +75,6 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
     docker :ps, "-q", *service_filter
   end
 
-  def container_id_for(container_name:)
-    docker :container, :ls, "-a", "-f", "name=#{container_name}", "-q"
-  end
-
   def current_running_version
     # FIXME: Find more graceful way to extract the version from "app-version" than using sed and tail!
     pipe \

lib/mrsk/commands/base.rb

@@ -17,6 +17,10 @@ module Mrsk::Commands
       end
     end
 
+    def container_id_for(container_name:)
+      docker :container, :ls, "-a", "-f", "name=#{container_name}", "-q"
+    end
+
     private
       def combine(*commands, by: "&&")
         commands

lib/mrsk/commands/healthcheck.rb

@@ -0,0 +1,46 @@
+class Mrsk::Commands::Healthcheck < Mrsk::Commands::Base
+  EXPOSED_PORT = 3999
+
+  def run
+    web = config.role(:web)
+
+    docker :run,
+      "-d",
+      "--name", container_name_with_version,
+      "-p", "#{EXPOSED_PORT}:#{config.healthcheck["port"]}",
+      "--label", "service=#{container_name}",
+      *web.env_args,
+      *config.volume_args,
+      config.absolute_image,
+      web.cmd
+  end
+
+  def curl
+    [ :curl, "--silent", "--output", "/dev/null", "--write-out", "'%{http_code}'", health_url ]
+  end
+
+  def stop
+    pipe \
+      container_id_for(container_name: container_name),
+      xargs(docker(:stop))
+  end
+
+  def remove
+    pipe \
+      container_id_for(container_name: container_name),
+      xargs(docker(:container, :rm))
+  end
+
+  private
+    def container_name
+      "healthcheck-#{config.service}"
+    end
+
+    def container_name_with_version
+      "healthcheck-#{config.service_with_version}"
+    end
+
+    def health_url
+      "http://localhost:#{EXPOSED_PORT}#{config.healthcheck["path"]}"
+    end
+end