Convert file publisher to be equivalent to file dispatcher

Deprecate the file dispatcher and now file publisher can do
the same instead. And add a release note about it.

Change-Id: I6a5040e2e57389f9f7f5d246c528f8c49cfc05d8
Related-Bug: #1630570

ceilometer/dispatcher/file.py

@@ -16,6 +16,7 @@
 import logging
 import logging.handlers
 
+from debtcollector import removals
 from oslo_config import cfg
 
 from ceilometer import dispatcher
@@ -35,6 +36,8 @@ OPTS = [
 cfg.CONF.register_opts(OPTS, group="dispatcher_file")
 
 
+@removals.removed_class("FileDispatcher", message="Use file publisher instead",
+                        removal_version="9.0.0")
 class FileDispatcher(dispatcher.MeterDispatcherBase,
                      dispatcher.EventDispatcherBase):
     """Dispatcher class for recording metering data to a file.

ceilometer/publisher/file.py

@@ -19,7 +19,6 @@ import logging.handlers
 from oslo_log import log
 from six.moves.urllib import parse as urlparse
 
-import ceilometer
 from ceilometer.i18n import _
 from ceilometer import publisher
 
@@ -29,7 +28,7 @@ LOG = log.getLogger(__name__)
 class FilePublisher(publisher.ConfigPublisherBase):
     """Publisher metering data to file.
 
-    The publisher which records metering data into a file. The file name and
+    The file publisher pushes metering data into a file. The file name and
     location should be configured in ceilometer pipeline configuration file.
     If a file name and location is not specified, this File Publisher will not
     log any meters other than log a warning in Ceilometer log file.
@@ -58,7 +57,7 @@ class FilePublisher(publisher.ConfigPublisherBase):
 
         self.publisher_logger = None
         path = parsed_url.path
-        if not path or path.lower() == 'file':
+        if not path:
             LOG.error(_('The path for the file publisher is required'))
             return
 
@@ -101,4 +100,6 @@ class FilePublisher(publisher.ConfigPublisherBase):
 
         :param events: events from pipeline after transformation
         """
-        raise ceilometer.NotImplementedError
+        if self.publisher_logger:
+            for event in events:
+                self.publisher_logger.info(event.as_dict())

releasenotes/notes/deprecate-file-dispatcher-2aff376db7609136.yaml

@@ -0,0 +1,6 @@
+---
+deprecations:
+  - With collector service being deprecated, we now have to
+    address the duplication between dispatchers and publishers.
+    The file dispatcher is now marked as deprecated. Use the
+    file publisher to push samples into a file.