cassandra: rewrote service from scratch

Adds a replacement for the previously broken
`services.database.cassandra` with tests for a multi-node setup.

nixos/doc/manual/release-notes/rl-1809.xml

@@ -73,6 +73,14 @@ $ nix-instantiate -E '(import <nixpkgsunstable> {}).gitFull'
   </para>
 
   <itemizedlist>
+   <listitem>
+    <para>
+     The <varname>services.cassandra</varname> module has been reworked and
+     was rewritten from scratch. The service has succeeding tests for
+     the versions 2.1, 2.2, 3.0 and 3.11 of <link
+     xlink:href="https://cassandra.apache.org/">Apache Cassandra</link>.
+    </para>
+   </listitem>
    <listitem>
     <para>
      There is a new <varname>services.foundationdb</varname> module for deploying
@@ -119,6 +127,12 @@ $ nix-instantiate -E '(import &lt;nixpkgsunstable&gt; {}).gitFull'
   </para>
 
   <itemizedlist>
+   <listitem>
+    <para>
+     The deprecated <varname>services.cassandra</varname> module has
+     seen a complete rewrite. (See above.)
+    </para>
+   </listitem>
    <listitem>
     <para>
      <literal>lib.strict</literal> is removed. Use

nixos/modules/misc/ids.nix

@@ -324,6 +324,7 @@
       hadoop = 297;
       hydron = 298;
       cfssl = 299;
+      cassandra = 300;
 
       # When adding a uid, make sure it doesn't match an existing gid. And don't use uids above 399!
 
@@ -608,6 +609,7 @@
       hadoop = 297;
       hydron = 298;
       cfssl = 299;
+      cassandra = 300;
 
       # When adding a gid, make sure it doesn't match an existing
       # uid. Users and groups with the same name should have equal

nixos/modules/module-list.nix

@@ -201,6 +201,7 @@
   ./services/databases/4store-endpoint.nix
   ./services/databases/4store.nix
   ./services/databases/aerospike.nix
+  ./services/databases/cassandra.nix
   ./services/databases/clickhouse.nix
   ./services/databases/couchdb.nix
   ./services/databases/firebird.nix