changing disk thresholds via juju config has no effect

[Paul Collins]

I ran:

juju config cassandra nagios_disk_crit_pct=20 nagios_disk_warn_pct=25

Nothing changed in /etc/nagios/nrpe.d, and the unit agents logged, e.g.:

2018-09-24 21:24:37 INFO juju-log Reactive main running for hook config-changed
2018-09-24 21:24:38 DEBUG juju-log Coordinator: Using charms.coordinator.SimpleCoordinator coordinator
2018-09-24 21:24:38 INFO juju-log Initializing Snap Layer
2018-09-24 21:24:38 DEBUG config-changed none
2018-09-24 21:24:38 DEBUG juju-log Coordinator: Loading state
2018-09-24 21:24:38 INFO juju-log Coordinator: Initializing coordinator layer
2018-09-24 21:24:38 INFO juju-log Initializing Leadership Layer (is follower)
2018-09-24 21:24:39 INFO juju-log Initializing Apt Layer
2018-09-24 21:24:39 DEBUG juju-log Adding key lib/apache.key
2018-09-24 21:24:39 DEBUG juju-log Adding key lib/datastax.key
2018-09-24 21:24:40 INFO juju-log Invoking reactive handler: reactive/apt.py:48:ensure_package_status
2018-09-24 21:24:40 INFO juju-log Invoking reactive handler: reactive/cassandra/status.py:26:is_live
2018-09-24 21:24:40 DEBUG juju-log listen_ip_address == '10.22.96.51'
2018-09-24 21:24:40 INFO juju-log active: Live seed
2018-09-24 21:24:40 INFO juju-log Invoking reactive handler: reactive/cassandra/cluster.py:101:set_bootstrapped
2018-09-24 21:24:40 DEBUG juju-log listen_ip_address == '10.22.96.51'
2018-09-24 21:24:40 INFO juju-log Invoking reactive handler: reactive/cassandra/client.py:35:trigger_publish
2018-09-24 21:24:40 INFO juju-log Invoking reactive handler: reactive/cassandra/config.py:119:validate_config
2018-09-24 21:24:40 INFO juju-log new_confg[authenticator] = PasswordAuthenticator
2018-09-24 21:24:40 INFO juju-log new_confg[edition] = community
2018-09-24 21:24:41 INFO juju-log new_confg[jre] = openjdk
2018-09-24 21:24:41 INFO juju-log new_confg[dse_version] = 6.0
2018-09-24 21:24:41 INFO juju-log Invoking reactive handler: reactive/cassandra/install.py:152:install_packages
2018-09-24 21:24:41 DEBUG juju-log Writing file /etc/apt/preferences.d/cassandra_charm root:root 444
2018-09-24 21:24:41 INFO juju-log Invoking reactive handler: reactive/cassandra/install.py:263:update_etc_hosts
2018-09-24 21:24:41 DEBUG juju-log listen_ip_address == '10.22.96.51'
2018-09-24 21:24:41 DEBUG juju-log Marking line '10.22.96.51 adhafera' for update or removal
2018-09-24 21:24:41 INFO juju-log Invoking reactive handler: reactive/cassandra/install.py:306:reset_all_io_schedulers
2018-09-24 21:24:43 INFO juju-log Making dir /var/lib/cassandra/commitlog cassandra:cassandra 750
2018-09-24 21:24:43 INFO juju-log Making dir /var/lib/cassandra/saved_caches cassandra:cassandra 750
2018-09-24 21:24:43 INFO juju-log Making dir /var/lib/cassandra/hints cassandra:cassandra 750
2018-09-24 21:24:43 INFO juju-log Making dir /srv/cassandra cassandra:cassandra 750
2018-09-24 21:24:44 DEBUG config-changed none
2018-09-24 21:24:44 INFO juju-log Setting block device of /srv/cassandra to IO scheduler noop
2018-09-24 21:24:44 DEBUG juju-log /sys/block/sdb/queue/scheduler already noop
2018-09-24 21:24:44 DEBUG config-changed none
2018-09-24 21:24:44 INFO juju-log Setting block device of /var/lib/cassandra/commitlog to IO scheduler noop
2018-09-24 21:24:44 DEBUG juju-log /sys/block/sda/queue/scheduler already noop
2018-09-24 21:24:44 DEBUG config-changed none
2018-09-24 21:24:44 INFO juju-log Setting block device of /var/lib/cassandra/saved_caches to IO scheduler noop
2018-09-24 21:24:44 DEBUG juju-log /sys/block/sda/queue/scheduler already noop
2018-09-24 21:24:44 INFO juju-log Invoking reactive handler: reactive/cassandra/config.py:164:configure_cassandra
2018-09-24 21:24:46 DEBUG juju-log Configuring seeds as '10.22.96.52,10.22.96.53,10.22.96.51'
2018-09-24 21:24:46 DEBUG juju-log listen_ip_address == '10.22.96.51'
2018-09-24 21:24:46 DEBUG juju-log rpc_ip_address == '10.22.96.51'
2018-09-24 21:24:47 DEBUG juju-log rpc_broadcast_ip_address == '10.22.96.51'
2018-09-24 21:24:50 DEBUG juju-log Writing file /etc/cassandra/cassandra.yaml root:root 444
2018-09-24 21:24:50 INFO juju-log Invoking reactive handler: reactive/cassandra/install.py:249:install_maintenance_crontab
2018-09-24 21:24:51 INFO juju-log Invoking reactive handler: reactive/cassandra/config.py:175:maybe_restart
2018-09-24 21:24:51 DEBUG juju-log Coordinator: Publishing state
2018-09-24 21:24:51 INFO juju.worker.uniter.operation runhook.go:120 ran "config-changed" hook