Refactor docker cmd arg building

This change refactors the arg building so that the logic is contained
in dedicated functions for 'docker run' and 'docker exec', instead of
being split between the main loop and docker_arg_map.

Minor changes in behaviour which don't affect the tests include:
- No longer force ascii encoding of arg values
- Extra check to ensure the command is a list before extending cmd
- Remove the unicode/empty-string list value check

Change-Id: I09f3d2ee98020de556a3d0aa72721fe8b7420b2a

heat-config-docker-cmd/install.d/hook-docker-cmd.py

@@ -36,19 +36,53 @@ def build_response(deploy_stdout, deploy_stderr, deploy_status_code):
     }
 
 
-def docker_arg_map(key, value):
-    value = str(value).encode('ascii', 'ignore')
-    return {
-        'environment': "--env=%s" % value,
-        'image': value,
-        'net': "--net=%s" % value,
-        'pid': "--pid=%s" % value,
-        'privileged': "--privileged=%s" % value.lower(),
-        'restart': "--restart=%s" % value,
-        'user': "--user=%s" % value,
-        'volumes': "--volume=%s" % value,
-        'volumes_from': "--volumes-from=%s" % value,
-    }.get(key, None)
+def docker_run_args(cmd, container, config):
+    cconfig = config[container]
+    if cconfig.get('detach', True):
+        cmd.append('--detach=true')
+    for v in cconfig.get('environment', []):
+        if v:
+            cmd.append('--env=%s' % v)
+    if 'net' in cconfig:
+        cmd.append('--net=%s' % cconfig['net'])
+    if 'pid' in cconfig:
+        cmd.append('--pid=%s' % cconfig['pid'])
+    if 'privileged' in cconfig:
+        cmd.append('--privileged=%s' % str(cconfig['privileged']).lower())
+    if 'restart' in cconfig:
+        cmd.append('--restart=%s' % cconfig['restart'])
+    if 'user' in cconfig:
+        cmd.append('--user=%s' % cconfig['user'])
+    for v in cconfig.get('volumes', []):
+        if v:
+            cmd.append('--volume=%s' % v)
+    for v in cconfig.get('volumes_from', []):
+        if v:
+            cmd.append('--volumes_from=%s' % v)
+
+    cmd.append(cconfig.get('image', ''))
+    cmd.extend(command_argument(cmd, cconfig.get('command')))
+
+
+def docker_exec_args(cmd, container, config, cid):
+    cconfig = config[container]
+    if 'privileged' in cconfig:
+        cmd.append('--privileged=%s' % str(cconfig['privileged']).lower())
+    if 'user' in cconfig:
+        cmd.append('--user=%s' % cconfig['user'])
+    command = command_argument(cmd, cconfig.get('command'))
+    # for exec, the first argument is the container name,
+    # make sure the correct one is used
+    command[0] = discover_container_name(command[0], cid)
+    cmd.extend(command)
+
+
+def command_argument(cmd, command):
+    if not command:
+        return []
+    if not isinstance(command, list):
+        return [command]
+    return command
 
 
 def execute(cmd):
@@ -144,6 +178,7 @@ def main(argv=sys.argv):
         return
 
     config = c.get('config', '')
+    cid = c.get('id')
     if not config:
         log.debug("No 'config' input found, nothing to do.")
         json.dump(build_response(
@@ -171,41 +206,11 @@ def main(argv=sys.argv):
                 '--name',
                 unique_container_name(container)
             ]
-            label_arguments(cmd, container, c.get('id'), input_values)
-            if config[container].get('detach', True):
-                cmd.append('--detach=true')
+            label_arguments(cmd, container, cid, input_values)
+            docker_run_args(cmd, container, config)
         elif action == 'exec':
             cmd = [DOCKER_CMD, 'exec']
-
-        image_name = ''
-        for key in sorted(config[container]):
-            # These ones contain a list of values
-            if key in ['environment', 'volumes', 'volumes_from']:
-                for value in config[container][key]:
-                    # Somehow the lists get empty values sometimes
-                    if type(value) is unicode and not value.strip():
-                        continue
-                    cmd.append(docker_arg_map(key, value))
-            elif key == 'image':
-                image_name = config[container][key].encode('ascii', 'ignore')
-            else:
-                arg = docker_arg_map(key, config[container][key])
-                if arg:
-                    cmd.append(arg)
-
-        # Image name and command come last.
-        if action == 'run':
-            cmd.append(image_name)
-
-        if 'command' in config[container]:
-            command = config[container].get('command')
-
-            if action == 'exec':
-                # for exec, the first argument is the container name,
-                # make sure the correct one is used
-                command[0] = discover_container_name(command[0], c.get('id'))
-
-            cmd.extend(command)
+            docker_exec_args(cmd, container, config, cid)
 
         (cmd_stdout, cmd_stderr, returncode) = execute(cmd)
         if cmd_stdout: