host select: replace host appointer with host select

cylc/flow/cfgspec/globalcfg.py

@@ -272,12 +272,7 @@
         'run ports': [VDR.V_INTEGER_LIST, list(range(43001, 43101))],
         'condemned hosts': [VDR.V_ABSOLUTE_HOST_LIST],
         'auto restart delay': [VDR.V_INTERVAL],
-        'thresholds': [VDR.V_STRING],
-        'run host select': {
-            'rank': [VDR.V_STRING, 'random', 'load:1', 'load:5', 'load:15',
-                     'memory', 'disk-space'],
-            'thresholds': [VDR.V_STRING],
-        },
+        'thresholds': [VDR.V_STRING]
     },
 }
 

cylc/flow/scheduler.py

@@ -42,12 +42,13 @@
 from cylc.flow.daemonize import daemonize
 from cylc.flow.exceptions import (
     CylcError,
+    HostSelectException,
     PointParsingError,
     SuiteServiceFileError,
     TaskProxySequenceBoundsError
 )
 import cylc.flow.flags
-from cylc.flow.host_appointer import HostAppointer, EmptyHostList
+from cylc.flow.host_select import select_suite_host
 from cylc.flow.hostuserutil import get_host, get_user, get_fqdn_by_host
 from cylc.flow.job_pool import JobPool
 from cylc.flow.loggingutil import (
@@ -1357,7 +1358,7 @@ def suite_auto_restart(self, max_retries=3):
         cmd = ['cylc', 'restart', quote(self.suite)]
 
         for attempt_no in range(max_retries):
-            new_host = HostAppointer(cached=False).appoint_host()
+            new_host = select_suite_host(cached=False)[1]
             LOG.info('Attempting to restart on "%s"', new_host)
 
             # proc will start with current env (incl CYLC_HOME etc)
@@ -1450,8 +1451,8 @@ def can_auto_restart(self):
         """Determine whether this suite can safely auto stop-restart."""
         # Check whether there is currently an available host to restart on.
         try:
-            HostAppointer(cached=False).appoint_host()
-        except EmptyHostList:
+            select_suite_host(cached=False)
+        except HostSelectException:
             LOG.critical(
                 'Suite cannot automatically restart because:\n' +
                 'No alternative host to restart suite on.')

cylc/flow/scheduler_cli.py

@@ -21,7 +21,7 @@
 
 import cylc.flow.flags
 from cylc.flow.exceptions import SuiteServiceFileError
-from cylc.flow.host_appointer import HostAppointer, EmptyHostList
+from cylc.flow.host_select import select_suite_host
 from cylc.flow.hostuserutil import is_remote_host
 from cylc.flow.option_parsers import CylcOptionParser as COP
 from cylc.flow.pathutil import get_suite_run_dir
@@ -249,13 +249,7 @@ def scheduler_cli(parser, options, args, is_restart=False):
 
     # Check whether a run host is explicitly specified, else select one.
     if not options.host:
-        try:
-            host = HostAppointer().appoint_host()
-        except EmptyHostList as exc:
-            if cylc.flow.flags.debug:
-                raise
-            else:
-                sys.exit(str(exc))
+        host = select_suite_host()[1]
         if is_remote_host(host):
             if is_restart:
                 base_cmd = ["restart"] + sys.argv[1:]