guest_id missing err, switch config_drive default

This changes the default setting for use_nova_server_config_drive
from False to True. By default, nova does not use a config
drive for launched instances. Therefore trove must implicitly
request the config drive be used so that it can inject
guest_info.conf into the guest VM.

This commit also adds an error to guestagent when guest_id
is missing. If the guest_id configuration parameter is not
set at guestagent startup it will throw a RuntimeError. This
case typically occurs because guest_info.conf was
not injected into the guest, or was not included in the set
of configs that guestagent reads at startup.

And finally, this commit adds a section in the 'building guest
images' documentation describing how configuration is injected
into the guest agent.

Change-Id: I084c841472183893a63ca7b70d560f44a2f08901
Partial-Bug: 1609915
(cherry picked from commit f7b8805c3a)

doc/source/dev/building_guest_images.rst

@@ -79,6 +79,20 @@ API for the specific database.
 
 The Trove Guest Agent runs on the Trove Guest Instance.
 
+------------------------------------------
+Injected Configuration for the Guest Agent
+------------------------------------------
+
+When TaskManager launches the guest VM it injects the specific settings
+for the guest into the VM, into the file /etc/trove/conf.d/guest_info.conf.
+The file is injected one of three ways. If use_heat=True, it is injected
+during the heat launch process. If use_nova_server_config_drive=True
+it is injected via ConfigDrive. Otherwise it is passed to the nova
+create call as the 'files' parameter and will be injected based on
+the configuration of Nova; the Nova default is to discard the files.
+If the settings in guest_info.conf are not present on the guest
+Guest Agent will fail to start up.
+
 ------------------------------
 Persistent Storage, Networking
 ------------------------------

etc/trove/trove-taskmanager.conf.sample

@@ -64,7 +64,7 @@ server_delete_time_out=480
 # Nova server boot options
 # sets the --config-drive argument when doing a nova boot
 # (controls how file injection is handled by nova)
-use_nova_server_config_drive = False
+use_nova_server_config_drive = True
 
 # Configuration options for talking to nova via the novaclient.
 # These options are for an admin user in your keystone config.

trove/cmd/guest.py

@@ -40,10 +40,15 @@ def main():
     from trove.guestagent import dbaas
     manager = dbaas.datastore_registry().get(CONF.datastore_manager)
     if not manager:
-        msg = ("Manager class not registered for datastore manager %s" %
+        msg = (_LE("Manager class not registered for datastore manager %s") %
                CONF.datastore_manager)
         raise RuntimeError(msg)
 
+    if not CONF.guest_id:
+        msg = (_LE("The guest_id parameter is not set. guest_info.conf "
+               "was not injected into the guest or not read by guestagent"))
+        raise RuntimeError(msg)
+
     # rpc module must be loaded after decision about thread monkeypatching
     # because if thread module is not monkeypatched we can't use eventlet
     # executor from oslo_messaging library.

trove/common/cfg.py

@@ -190,7 +190,7 @@ common_opts = [
     cfg.IntOpt('trove_conductor_workers',
                help='Number of workers for the Conductor service. The default '
                'will be the number of CPUs available.'),
-    cfg.BoolOpt('use_nova_server_config_drive', default=False,
+    cfg.BoolOpt('use_nova_server_config_drive', default=True,
                 help='Use config drive for file injection when booting '
                 'instance.'),
     cfg.BoolOpt('use_nova_server_volume', default=False,