anchor.diff:    jmxRolesFile = ./cassandra-jmx-roles;
     jmxAuthArgs = "-u ${(builtins.elemAt jmxRoles 0).username} -pw ${(builtins.elemAt jmxRoles 0).password}";
     jmxPort = 7200;  # Non-standard port so it doesn't accidentally work
  +  jmxPortStr = toString jmxPort;
   
  -  # Would usually be assigned to 512M
  +  # Would usually be assigned to 512M.
  +  # Set it to a different value, so that we can check whether our config
  +  # actually changes it.
     numMaxHeapSize = "400";
     getHeapLimitCommand = ''
  -    nodetool info -p ${toString jmxPort} | grep "^Heap Memory" | awk \'{print $NF}\'
  +    nodetool info -p ${jmxPortStr} | grep "^Heap Memory" | awk '{print $NF}'
     '';
  -  checkHeapLimitCommand = ''
  +  checkHeapLimitCommand = pkgs.writeShellScript "check-heap-limit.sh" ''
       [ 1 -eq "$(echo "$(${getHeapLimitCommand}) < ${numMaxHeapSize}" | ${pkgs.bc}/bin/bc)" ]
     '';
   
  
positive.code:     cass2 = nodeCfg "192.168.1.3" { jvmOpts = [ "-Dcassandra.replace_address=cass1" ]; };
    };
  
    testScript = let
      jmxPortS = toString jmxPort;
    in ''
      # Check configuration
      subtest "Timers exist", sub {
        $cass0->succeed("systemctl list-timers | grep cassandra-full-repair.timer");
        $cass0->succeed("systemctl list-timers | grep cassandra-incremental-repair.timer");
      };
      subtest "Can connect via cqlsh", sub {
        $cass0->waitForUnit("cassandra.service");
        $cass0->waitUntilSucceeds("nc -z cass0 9042");
        $cass0->succeed("echo 'show version;' | cqlsh cass0");
      };
      subtest "Nodetool is operational", sub {
        $cass0->waitForUnit("cassandra.service");
        $cass0->waitUntilSucceeds("nc -z localhost ${jmxPortS}");
        $cass0->succeed("nodetool status -p ${jmxPortS} --resolve-ip | egrep '^UN[[:space:]]+cass0'");
      };
      subtest "Cluster name was set", sub {
        $cass0->waitForUnit("cassandra.service");
        $cass0->waitUntilSucceeds("nc -z localhost ${jmxPortS}");
        $cass0->waitUntilSucceeds("nodetool describecluster -p ${jmxPortS} | grep 'Name: ${clusterName}'");
      };
      subtest "Heap limit set correctly", sub {
        # Nodetool takes a while until it can display info
        $cass0->waitUntilSucceeds('nodetool info -p ${jmxPortS}');
        $cass0->succeed('${checkHeapLimitCommand}');
      };
  
      # Check cluster interaction
      subtest "Bring up cluster", sub {
        $cass1->waitForUnit("cassandra.service");
        $cass1->waitUntilSucceeds("nodetool -p ${jmxPortS} ${jmxAuthArgs} status | egrep -c '^UN' | grep 2");
        $cass0->succeed("nodetool status -p ${jmxPortS} --resolve-ip | egrep '^UN[[:space:]]+cass1'");
      };
    '' + lib.optionalString testRemoteAuth ''
      subtest "Remote authenticated jmx", sub {
        # Doesn't work if not enabled
        $cass0->waitUntilSucceeds("nc -z localhost ${jmxPortS}");
        $cass1->fail("nc -z 192.168.1.1 ${toString jmxPort}");
        $cass1->fail("nodetool -p ${jmxPortS} -h 192.168.1.1 status");
  
        # Works if enabled
        $cass1->waitUntilSucceeds("nc -z localhost ${toString jmxPort}");
        $cass0->succeed("nodetool -p ${jmxPortS} -h 192.168.1.2 ${jmxAuthArgs} status");
      };
    '' + ''
      subtest "Break and fix node", sub {
        $cass1->block;
        $cass0->waitUntilSucceeds("nodetool status -p ${jmxPortS} --resolve-ip | egrep -c '^DN[[:space:]]+cass1'");
        $cass0->succeed("nodetool status -p ${jmxPortS} | egrep -c '^UN'  | grep 1");
        $cass1->unblock;
        $cass1->waitUntilSucceeds("nodetool -p ${jmxPortS} ${jmxAuthArgs} status | egrep -c '^UN'  | grep 2");
        $cass0->succeed("nodetool status -p ${jmxPortS} | egrep -c '^UN'  | grep 2");
      };
      subtest "Replace crashed node", sub {
        $cass1->crash;
        $cass2->waitForUnit("cassandra.service");
        $cass0->waitUntilFails("nodetool status -p ${jmxPortS} --resolve-ip | egrep '^UN[[:space:]]+cass1'");
        $cass0->waitUntilSucceeds("nodetool status -p ${jmxPortS} --resolve-ip | egrep '^UN[[:space:]]+cass2'");
      };
    '';
  })
  
negative.code:   };
  in
  {
    name = "cassandra";
    meta = {
      maintainers = with lib.maintainers; [ johnazoidberg ];
    };
  
    nodes = {
      cass0 = nodeCfg "192.168.1.1" {};
  