[DCOS-48462][Cassandra] Honor config JMX_PORT (#2927)

Apache Cassandra 3.11+ adds in new logic and classes for parsing the JMX_PORT from cassandra-env.sh which is hardcoded to 7199. This commit replaces the value in the file with the user-specified framework config

frameworks/cassandra/src/main/dist/svc.yml

@@ -66,6 +66,9 @@ pods:
                     ARGS="$ARGS -R"
                 fi
 
+                # Honor jmx_port config otherwise Cassandra will hardcode to 7199
+                sed -i 's/JMX_PORT=.*/JMX_PORT="{{TASKCFG_ALL_JMX_PORT}}"/' apache-cassandra-{{CASSANDRA_VERSION}}/conf/cassandra-env.sh
+
                 exec ./apache-cassandra-{{CASSANDRA_VERSION}}/bin/cassandra $ARGS
         configs:
           cassandra:

frameworks/cassandra/tests/test_sanity.py

@@ -1,12 +1,15 @@
 import pytest
 import logging
 
+import sdk_cmd
 import sdk_hosts
 import sdk_install
 import sdk_jobs
 import sdk_metrics
 import sdk_networks
 import sdk_plan
+import sdk_service
+import sdk_tasks
 import sdk_upgrade
 
 from tests import config
@@ -96,3 +99,25 @@ def expected_metrics_exist(emitted_metrics):
         config.DEFAULT_CASSANDRA_TIMEOUT,
         expected_metrics_exist,
     )
+
+
+@pytest.mark.sanity
+def test_custom_jmx_port():
+    expected_open_port = ":7200 (LISTEN)"
+
+    new_config = {"cassandra": {"jmx_port": 7200}}
+
+    sdk_service.update_configuration(
+        config.PACKAGE_NAME,
+        config.get_foldered_service_name(),
+        new_config,
+        config.DEFAULT_TASK_COUNT,
+    )
+
+    sdk_plan.wait_for_completed_deployment(config.get_foldered_service_name())
+
+    tasks = sdk_tasks.get_service_tasks(config.get_foldered_service_name(), "node")
+
+    for task in tasks:
+        _, stdout, _ = sdk_cmd.run_cli("task exec {} lsof -i :7200".format(task.id))
+        assert expected_open_port in stdout