Add log_tag option to container definition

This adds the --log-opt tag=<value> to the docker run command, which can
be quite useful depending on your logging needs.

In the TripleO case, we use journald as the default logging driver, and
this will get reflected in the logs by adding the tag to the
CONTAINER_TAG key in the log metadata.

bp logging-stdout-rsyslog

Change-Id: I3bfb1a5ce2d6a6f95519f5272348eae18d649712

README.rst

@@ -287,3 +287,6 @@ volumes:
 
 volumes_from:
   List of strings. Mount volumes from the specified container(s).
+
+log_tag:
+  String. Set the log tag for the specified container.

paunch/builder/compose1.py

@@ -173,6 +173,8 @@ class ComposeV1Builder(object):
         for v in cconfig.get('volumes_from', []):
             if v:
                 cmd.append('--volumes-from=%s' % v)
+        if 'log_tag' in cconfig:
+            cmd.append('--log-opt=tag=%s' % cconfig['log_tag'])
 
         cmd.append(cconfig.get('image', ''))
         cmd.extend(self.command_argument(cconfig.get('command')))

paunch/tests/test_builder_compose1.py

@@ -324,6 +324,7 @@ three-12345678 three''', '', 0),
                     'retries': 3
                 },
                 'env_file': '/tmp/foo.env',
+                'log_tag': '{{.ImageName}}/{{.Name}}/{{.ID}}'
             }
         }
         builder = compose1.ComposeV1Builder('foo', config, None)
@@ -337,7 +338,7 @@ three-12345678 three''', '', 0),
              '--health-cmd=/bin/true', '--health-interval=30s',
              '--health-timeout=10s', '--health-retries=3',
              '--privileged=true', '--restart=always', '--user=bar',
-             'centos:7'],
+             '--log-opt=tag={{.ImageName}}/{{.Name}}/{{.ID}}', 'centos:7'],
             cmd
         )
 

releasenotes/notes/Add-log-tag-option-f63140a497abf370.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    the log_tag option was added to the container definition. This will make
+    paunch add the --log-opt tag=<value> option to the run command.