Disable nagios installation by default

Packstack install nagios server in controller node
by default. Given the lack of integration between nagios
and OpenStack services provided as deployed by packstack,
i think this shouldn't be the case.

This patch disables nagios installation by default.

Change-Id: I19df1a09d971a06ee94dc543a003a5fd55dcb1f2

packstack/plugins/prescript_000.py

@@ -363,7 +363,7 @@ def initConfig(controller):
              ),
              "OPTION_LIST": ["y", "n"],
              "VALIDATORS": [validators.validate_options],
-             "DEFAULT_VALUE": 'y',
+             "DEFAULT_VALUE": 'n',
              "MASK_INPUT": False,
              "LOOSE_VALIDATION": False,
              "CONF_NAME": "CONFIG_NAGIOS_INSTALL",

releasenotes/notes/change-default-nagios-b190de0737165bf9.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Default value for configuration option CONFIG_NAGIOS_INSTALL has been
+    changed to 'n' in Ocata. Users that require nagios installation in their
+    packstack deployent will need to explicitely modify it to 'y' using
+    answers file or command line option '--nagios-install'.

tests/scenario001.sh

@@ -26,6 +26,7 @@ $SUDO packstack ${ADDITIONAL_ARGS} \
           --os-swift-install=n \
           --os-manila-install=y \
           --os-horizon-ssl=y \
+          --nagios-install=y \
           --amqp-enable-ssl=y \
           --glance-backend=file \
           --provision-uec-kernel-url="/tmp/cirros/cirros-0.3.4-x86_64-vmlinuz" \