Fix devstack deployment by restoring ceilosca_pipeline.yaml

In our efforts to clean up meters that were removed from Ceilometer
in the Rocky release (see c514916761 )
the ceilosca_pipeline.yaml was deleted. However, that file is needed
for the devstack plugin, as specified in devstack/settings .

This patch restores that file, and renames it to make the purpose
clearer.

Also added comments to the pipeline.yaml files to indicate their
purpose.

Change-Id: I28de9011d3e8c73f9d5057c8ca05cd42d3262dfc

devstack/settings

@@ -10,5 +10,5 @@ MONASCA_API_URL=http://$SERVICE_HOST/metrics/v2.0
 
 CEILOSCA_DIR=$DEST/ceilosca
 CEILOSCA_FILES='ceilometer/monasca_client.py ceilometer/publisher/monasca_data_filter.py ceilometer/publisher/monasca.py ceilometer/opts.py ceilometer/monasca_opts.py ../devstack/setup.cfg:.'
-CEILOSCA_CONF_FILES='ceilosca_pipeline.yaml:pipeline.yaml monasca_field_definitions.yaml'
+CEILOSCA_CONF_FILES='ceilosca-devstack_pipeline.yaml:pipeline.yaml monasca_field_definitions.yaml'
 CEILOSCA_USER=$USER

etc/ceilometer/ceilosca-devstack_pipeline.yaml

@@ -0,0 +1,19 @@
+# This simple pipeline.yaml is copied in to place by the devstack/plugin.sh
+# as specified in devstack/settings.
+---
+sources:
+    - name: meter_source
+      interval: 60
+      meters:
+        - "image.size"
+#        - "image.download"
+#        - "image.serve"
+        - "snapshot.size"
+        - "volume.size"
+      sinks:
+        - meter_sink
+sinks:
+    - name: meter_sink
+      transformers:
+      publishers:
+        - monasca://INSERT-URL-HERE

etc/ceilometer/monasca_pipeline.yaml

@@ -1,3 +1,5 @@
+# This pipeline.yaml is used for unit testing of Monasca Ceilometer and does
+# not represent real measurements from Ceilometer.
 ---
 sources:
     - name: meter_source

etc/ceilometer/pipeline.yaml

@@ -1,3 +1,6 @@
+# An example pipeline.yaml
+# Reference https://docs.openstack.org/ceilometer/latest/admin/telemetry-measurements.html
+# for other possible meters.
 ---
 sources:
     - name: compute_source
@@ -17,9 +20,6 @@ sources:
       interval: 30
       meters:
           - "image.size"
-          - "image.update"
-          - "image.upload"
-          - "image.delete"
       sinks:
           - meter_sink
     - name: volume_source