Kafka alert generator

Addresses #388 (closed), and depends on !851 (merged).

Feb 11 edit: First attempt at adding the code to publish to a kafka topic is done, needs testing. Alerts currently set to publish to StandinKafkaTopic

Aug 10 edit: Ready to be reviewed. Need new release of hop-client for a PR needed for GCN support (merged) and need to update URL of avro schema files once userguide!124 (merged) is merged.

Sep 21 edit: Peeled a lot of these changes off into other MRs, specifically !914 (merged), !915 (merged), and !917 (merged). This MR now primarily deals with the work needed to plug the kafka alerts into the orchestrator.

To-Do list:

• Test sending avro packet to kafka producer
• Decide where to store avro schema files for deployed instances to read
• Write unit tests to...
  • Validate that avro packet constructed by voevent is correct
  • Check that avro packet is sent to kafka producer

doc/gwcelery.tasks.orchestrator.rst

@@ -14,7 +14,7 @@ The orchestrator consists of two IGWN Alert message handlers:
   stabilize, then performs data quality checks. If the data quality checks
   pass, then it calls
   :meth:`~gwcelery.tasks.orchestrator.earlywarning_preliminary_alert` to copy
-  annotations from the preferred event and send the preliminary GCN notice.
+  annotations from the preferred event and send the preliminary notice.
 
 * :meth:`~gwcelery.tasks.orchestrator.handle_cbc_event` is called for each CBC
   event. It performs some CBC-specific annotations that depend closely on the
@@ -100,8 +100,8 @@ The flow chart below illustrates the operation of these two tasks.
                 label = "Make sky\nmap plots"
             ]
 
-            send_gcn [
-                label = "Send preliminary\nGCN notice"
+            send_notice [
+                label = "Send preliminary\nnotice"
             ]
 
             circular [
@@ -122,7 +122,7 @@ The flow chart below illustrates the operation of these two tasks.
     far_threshold -> dqv [label = Yes, lhead = prelim_gcn_checks]
 
     dqv -> copy_from_preferred_event [label = No, lhead = cluster_preliminary_alert]
-    copy_from_preferred_event -> annotate_skymaps -> send_gcn -> circular
+    copy_from_preferred_event -> annotate_skymaps -> send_notice -> circular
 
     cbc_event [
         label = "IGWN Alert for\nfile added\nto CBC event"
@@ -223,12 +223,12 @@ shown below; the flow chart for update alerts is the same.
             label = "If sky map provided,\nthen make sky map plots"
         ]
 
-        send_gcn [
-            label = "Send\nGCN notice"
+        send_notice [
+            label = "Send\nnotice"
         ]
     }
 
-    annotate_skymaps -> send_gcn
+    annotate_skymaps -> send_notice
 
 Retraction Alerts
 ~~~~~~~~~~~~~~~~~
@@ -259,8 +259,8 @@ alerts, and at the moment must be invoked manually. A flow chart is shown below.
         href = "../gwcelery.tasks.orchestrator.html#gwcelery.tasks.orchestrator.retraction_alert"
         label = <<B><FONT face="monospace">retraction_alert</FONT></B>>
 
-        send_gcn [
-            label = "Send\nGCN notice"
+        send_notice [
+            label = "Send\nnotice"
         ]
     }