Allow for a configurable replication factor for reaper_db

Author: joaquincasares

README.md

@@ -431,9 +431,13 @@ node's status:
 
 Once the Cassandra node is online and accepting CQL connections,
 create the required `reaper_db` Cassandra keyspace to allow Reaper to save
-its cluster and scheduling data:
+its cluster and scheduling data.
 
-```docker-compose run initialize-reaper_db```
+By default, the `reaper_db` keyspace is created using a replication factor
+of 1. To change this replication factor, provide the intended replication
+factor as an optional argument:
+
+```docker-compose run initialize-reaper_db [$REPLICATION_FACTOR]```
 
 Wait a few moments for the `reaper_db` schema change to propagate,
 then start Reaper:

docker/initialize-reaper_db/Dockerfile

@@ -1,6 +1,8 @@
 FROM cassandra:3.11
 
-# create the required reaper_db keyspace to allow Reaper to store scheduling data
-CMD set -x \
-    && cqlsh cassandra -e \
-    "CREATE KEYSPACE IF NOT EXISTS reaper_db WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1 };"
+# create the reaper_db keyspace
+COPY docker-entrypoint.sh /
+ENTRYPOINT ["/docker-entrypoint.sh"]
+
+# use a default replication factor of 1
+CMD ["1"]

docker/initialize-reaper_db/docker-entrypoint.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+set -x
+
+REPLICATION_FACTOR=$1
+
+# create the required reaper_db keyspace to allow Reaper to store scheduling data
+cqlsh cassandra -e \
+    "CREATE KEYSPACE IF NOT EXISTS reaper_db \
+    WITH replication = {'class': 'SimpleStrategy', \
+                        'replication_factor': $REPLICATION_FACTOR };"