Improve Healthckecks for manila-operator

Manila-operator is currently doing limited actions when it comes
to doing healthchecks. This change enhances the probes so we can
do actual checks on the status of the manila services, by
implementing a simple HTTP server (as being done by the
cinder operator)

The HTTP server though will do the healthchecks using a command we
offer in Manila: manila-manage service list. The HTTP server will
take as arguments the type of service you are trying to ensure is
alive (share or scheduler) and the location of the manila
configuration file.

Manila-manage service list command does not require any kind of
additional client to be run, nor keystone tokens or additional
authentication steps are required. The command will simply get the
services that are already registered in the database.

Then, the HTTP server will check on the state of the services and
respond to the operator according to the state and filters
matching.

pkg/manilascheduler/statefulset.go

@@ -22,6 +22,7 @@ import (
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
 )
 
 const (
@@ -73,14 +74,14 @@ func StatefulSet(
 		}
 	} else {
 		args = append(args, ServiceCommand)
-		livenessProbe.Exec = &corev1.ExecAction{
-			Command: []string{
-				"/bin/true",
-			},
+		livenessProbe.HTTPGet = &corev1.HTTPGetAction{
+			Port: intstr.FromInt(8080),
 		}
-		startupProbe.Exec = livenessProbe.Exec
+		startupProbe.HTTPGet = livenessProbe.HTTPGet
 		probeCommand = []string{
-			"/bin/sleep", "infinity",
+			"/usr/local/bin/container-scripts/healthcheck.py",
+			"scheduler",
+			"/etc/manila/manila.conf.d",
 		}
 	}
 

pkg/manilashare/statefulset.go

@@ -22,6 +22,7 @@ import (
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
 )
 
 const (
@@ -75,16 +76,17 @@ func StatefulSet(
 		}
 	} else {
 		args = append(args, ServiceCommand)
-		// Use the HTTP probe now that we have a simple server running
-
-		livenessProbe.Exec = &corev1.ExecAction{
-			Command: []string{
-				"/bin/true",
-			},
+		livenessProbe.HTTPGet = &corev1.HTTPGetAction{
+			Port: intstr.FromInt(8080),
 		}
-		startupProbe.Exec = livenessProbe.Exec
+		startupProbe.HTTPGet = livenessProbe.HTTPGet
+		// Probe doesn't run kolla_set_configs because it uses the 'manila' uid
+		// and gid and doesn't have permissions to make files be owned by root,
+		// so manila.conf is in its original location
 		probeCommand = []string{
-			"/bin/sleep", "infinity",
+			"/usr/local/bin/container-scripts/healthcheck.py",
+			"share",
+			"/etc/manila/manila.conf.d",
 		}
 	}
 

templates/manila/bin/healthcheck.py

@@ -0,0 +1,214 @@
+#!/usr/bin/env python3
+#
+# Copyright 2023 Red Hat Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# Trivial HTTP server to check health of scheduler, and share services.
+# Manila-API has its own health check endpoint and does not need this.
+#
+# The only check this server currently does is using the manila-manage
+# service list command, which accesses DB directly and gets data related
+# to the services already registered in Manila.
+#
+# Manila-manage will allow us to keep imports minimal and also check on
+# what has already been registered in the manila-database, and with this
+# we can checks if services are up or not.
+#
+# For share services all enabled backends must be up to return 200, so it is
+# recommended to use a different pod for each backend to avoid one backend
+# affecting others.
+#
+# Requires the name of the service as the first argument (share,
+# scheduler) and optionally a second argument with the location of the
+# configuration directory (defaults to /etc/manila/manila.conf.d)
+
+from http import server
+import signal
+import subprocess
+import sys
+import time
+import threading
+
+from oslo_config import cfg
+
+
+HOSTNAME = ''
+SERVER_PORT = 8080
+CONF = cfg.CONF
+BINARIES = ('share', 'scheduler')
+STATE_UP = ":-)"
+STATUS_ENABLED = "enabled"
+
+
+class ServiceNotFoundException(Exception):
+
+    def __init__(self, filters={}):
+        self.message = "Service not found."
+        if filters:
+            self.message = f'Service not found with filters: {filters}'
+        super(ServiceNotFoundException, self).__init__(self.message)
+
+
+class ServiceNotUp(Exception):
+    message = "Service error: Service is not UP."
+
+    def __init__(self):
+        super(ServiceNotUp, self).__init__(self.message)
+
+
+class HeartbeatServer(server.BaseHTTPRequestHandler):
+    @classmethod
+    def initialize_class(cls, binary, config_dir):
+        """Calculate and initialize constants"""
+        cls.binary = 'manila-' + binary
+        cls.config_dir = config_dir
+
+        if binary != 'share':
+            services_filters = [
+                {'host': CONF.host,
+                 'state': STATE_UP,
+                 'status': STATUS_ENABLED,
+                 'binary': cls.binary}]
+        else:
+            services_filters = []
+            for backend in CONF.enabled_share_backends:
+                host = "%s@%s" % (CONF.host, backend)
+                services_filters.append({'host': host,
+                                         'status': STATUS_ENABLED,
+                                         'binary': cls.binary})
+
+        # Store the filters used to find out services.
+        cls.services_filters = services_filters
+
+    @staticmethod
+    def check_service(services, **filters):
+        # Check if services were already created and are registered in the db
+        our_services = [service for service in services
+                        if all(service.get(key, None) == value
+                               for key, value in filters.items())]
+        if not our_services:
+            raise ServiceNotFoundException(filters=filters)
+
+        num_services = len(our_services)
+        if num_services != 1:
+            print(f'{num_services} services found!: {our_services}')
+
+        ok = all(service['state'] == STATE_UP for service in our_services)
+        if not ok:
+            raise ServiceNotUp()
+
+    def _parse_service_list_output(self, services_list):
+        # Decode the characters, remove the line splits and the
+        # blank spaces
+        services_list = services_list.decode('utf-8').split('\n')
+        services_list = [service.split() for service in services_list]
+
+        # First line is related to the headers. We don't care about the
+        # updated at, so we drop it and sanitize the strings.
+        services_list_headers = services_list[0]
+        columns_to_ignore_starts_at = services_list_headers.index("Updated")
+        services_list_headers = (
+            services_list_headers[0:columns_to_ignore_starts_at])
+        services_list_headers = (
+            [header.lower() for header in services_list_headers])
+
+        # Remove the headers from the list, so we can iterate on the items
+        services_list.pop(0)
+
+        # Finaly, we can get a dictionary out of the manila-manage command.
+        services_dict_list = []
+
+        for service in services_list:
+            if service:
+                service_dict = {}
+                for i, header in enumerate(services_list_headers):
+                    service_dict[header] = service[i]
+                services_dict_list.append(service_dict)
+        return services_dict_list
+
+    def do_GET(self):
+        try:
+            cmd = ['manila-manage', '--config-dir', self.config_dir,
+                   '--nodebug', 'service', 'list']
+            services_list = subprocess.run(cmd, stdout=subprocess.PIPE)
+
+            services_list = services_list.stdout
+        except Exception as exc:
+            return self.send_error(
+                500,
+                'Failed to get existing services in the Manila ',
+                f'database: {exc}')
+
+        services = self._parse_service_list_output(services_list)
+
+        for service_filters in self.services_filters:
+            try:
+                self.check_service(services, **service_filters)
+            except Exception as exc:
+                return self.send_error(500, exc.args[0])
+
+        self.send_response(200)
+        self.send_header("Content-type", "text/html")
+        self.end_headers()
+        self.wfile.write('<html><body>OK</body></html>'.encode('utf-8'))
+
+
+def get_stopper(server):
+    def stopper(signal_number=None, frame=None):
+        print("Stopping server.")
+        server.shutdown()
+        server.server_close()
+        print("Server stopped.")
+        sys.exit(0)
+    return stopper
+
+
+if __name__ == "__main__":
+    if 3 < len(sys.argv) < 2 or sys.argv[1] not in BINARIES:
+        print('Healthcheck requires the binary type as argument (one of: '
+              + ', '.join(BINARIES) +
+              ') and optionally the location of the config directory.')
+        sys.exit(1)
+    binary = sys.argv[1]
+
+    cfg_dir = (
+        sys.argv[2] if len(sys.argv) == 3 else '/etc/manila/manila.conf.d')
+
+    # Due to our imports manila.common.config.global_opts are registered in
+    # manila/share/__init__.py bringing in the following config options we
+    # want: host, enabled_backends
+    # Initialize Oslo Config
+    CONF(['--config-dir', cfg_dir], project='manila')
+
+    HeartbeatServer.initialize_class(binary, cfg_dir)
+
+    webServer = server.HTTPServer((HOSTNAME, SERVER_PORT), HeartbeatServer)
+    stop = get_stopper(webServer)
+
+    # Need to run the server on a different thread because its shutdown method
+    # will block if called from the same thread, and the signal handler must be
+    # on the main thread in Python.
+    thread = threading.Thread(target=webServer.serve_forever)
+    thread.daemon = True
+    thread.start()
+    print(f"Manila Healthcheck Server started http://{HOSTNAME}:{SERVER_PORT}")
+    signal.signal(signal.SIGTERM, stop)
+
+    try:
+        while True:
+            time.sleep(60)
+    except KeyboardInterrupt:
+        pass
+    finally:
+        stop()