diff --git a/sky/serve/autoscalers.py b/sky/serve/autoscalers.py
index a9075beedfb..ecc673c7c03 100644
--- a/sky/serve/autoscalers.py
+++ b/sky/serve/autoscalers.py
@@ -1,6 +1,8 @@
 import logging
 import time
 
+from typing import Optional
+
 from sky.serve.infra_providers import InfraProvider
 from sky.serve.load_balancers import LoadBalancer
 
@@ -78,10 +80,10 @@ class RequestRateAutoscaler(Autoscaler):
 
     def __init__(self,
                  *args,
-                 query_interval: int = 10,
-                 upper_threshold: int = 10,
-                 lower_threshold: int = 2,
                  min_nodes: int = 1,
+                 max_nodes: Optional[int] = None,
+                 upper_threshold: Optional[int] = None,
+                 lower_threshold: Optional[int] = None,
                  cooldown: int = 60,
                  **kwargs):
         """
@@ -95,10 +97,11 @@ def __init__(self,
         :param kwargs:
         """
         super().__init__(*args, **kwargs)
-        self.query_interval = query_interval
+        self.min_nodes = min_nodes
+        self.max_nodes = max_nodes or min_nodes
+        self.query_interval = 60  # Therefore thresholds represent queries per minute.
         self.upper_threshold = upper_threshold
         self.lower_threshold = lower_threshold
-        self.min_nodes = min_nodes
         self.cooldown = cooldown
         self.last_scale_operation = 0  # Time of last scale operation.
 
@@ -132,14 +135,15 @@ def evaluate_scaling(self):
         scaled = True
         # Bootstrap case
         logger.info(f'Number of nodes: {num_nodes}')
-        if num_nodes == 0 and requests_per_node > 0:
+        if num_nodes < self.min_nodes:
             logger.info(f'Bootstrapping autoscaler.')
             self.scale_up(1)
             self.last_scale_operation = current_time
-        elif requests_per_node > self.upper_threshold:
-            self.scale_up(1)
-            self.last_scale_operation = current_time
-        elif requests_per_node < self.lower_threshold:
+        elif self.upper_threshold is not None and requests_per_node > self.upper_threshold:
+            if self.infra_provider.total_servers() < self.max_nodes:
+                self.scale_up(1)
+                self.last_scale_operation = current_time
+        elif self.lower_threshold is not None and requests_per_node < self.lower_threshold:
             if self.infra_provider.total_servers() > self.min_nodes:
                 self.scale_down(1)
                 self.last_scale_operation = current_time
diff --git a/sky/serve/common.py b/sky/serve/common.py
index 5f211dc5a10..5c791daa363 100644
--- a/sky/serve/common.py
+++ b/sky/serve/common.py
@@ -1,32 +1,83 @@
-import yaml
+from typing import Optional, Dict
+
+from sky.backends import backend_utils
+from sky.utils import schemas
+from sky.utils import ux_utils
 
 
 class SkyServiceSpec:
 
-    def __init__(self, yaml_path: str):
-        with open(yaml_path, 'r') as f:
-            self.task = yaml.safe_load(f)
-        if 'service' not in self.task:
-            raise ValueError('Task YAML must have a "service" section')
-        if 'port' not in self.task['service']:
-            raise ValueError('Task YAML must have a "port" section')
-        if 'readiness_probe' not in self.task['service']:
-            raise ValueError('Task YAML must have a "readiness_probe" section')
-        self._readiness_path = self.get_readiness_path()
-        self._app_port = self.get_app_port()
-
-    def get_readiness_path(self):
+    def __init__(
+        self,
+        readiness_path: str,
+        readiness_timeout: int,
+        app_port: int,
+        min_replica: int,
+        max_replica: Optional[int] = None,
+        qpm_upper_threshold: Optional[int] = None,
+        qpm_lower_threshold: Optional[int] = None,
+    ):
+        if max_replica is not None and max_replica < min_replica:
+            with ux_utils.print_exception_no_traceback():
+                raise ValueError(
+                    'max_replica must be greater than or equal to min_replica')
         # TODO: check if the path is valid
-        return f':{self.task["service"]["port"]}{self.task["service"]["readiness_probe"]}'
-
-    def get_app_port(self):
+        self._readiness_path = f':{app_port}{readiness_path}'
+        self._readiness_timeout = readiness_timeout
         # TODO: check if the port is valid
-        return f'{self.task["service"]["port"]}'
+        self._app_port = str(app_port)
+        self._min_replica = min_replica
+        self._max_replica = max_replica
+        self._qpm_upper_threshold = qpm_upper_threshold
+        self._qpm_lower_threshold = qpm_lower_threshold
+
+    @classmethod
+    def from_yaml_config(cls, config: Optional[Dict[str, str]]):
+        if config is None:
+            return None
+
+        backend_utils.validate_schema(config, schemas.get_service_schema(),
+                                      'Invalid service YAML:')
+
+        service_config = {}
+        service_config['readiness_path'] = config['readiness_probe']['path']
+        service_config['readiness_timeout'] = config['readiness_probe'][
+            'readiness_timeout']
+        service_config['app_port'] = config['port']
+        service_config['min_replica'] = config['replica_policy']['min_replica']
+        service_config['max_replica'] = config['replica_policy'].get(
+            'max_replica', None)
+        service_config['qpm_upper_threshold'] = config['replica_policy'].get(
+            'qpm_upper_threshold', None)
+        service_config['qpm_lower_threshold'] = config['replica_policy'].get(
+            'qpm_lower_threshold', None)
+
+        return SkyServiceSpec(**service_config)
 
     @property
     def readiness_path(self):
         return self._readiness_path
 
+    @property
+    def readiness_timeout(self):
+        return self._readiness_timeout
+
     @property
     def app_port(self):
         return self._app_port
+
+    @property
+    def min_replica(self):
+        return self._min_replica
+
+    @property
+    def max_replica(self):
+        return self._max_replica
+
+    @property
+    def qpm_upper_threshold(self):
+        return self._qpm_upper_threshold
+
+    @property
+    def qpm_lower_threshold(self):
+        return self._qpm_lower_threshold
diff --git a/sky/serve/controller.py b/sky/serve/controller.py
index dfe5a953764..d10f89ab957 100644
--- a/sky/serve/controller.py
+++ b/sky/serve/controller.py
@@ -9,6 +9,7 @@
 
 import time
 import threading
+import yaml
 
 from typing import Optional
 
@@ -83,10 +84,6 @@ def get_server_ips():
                         type=int,
                         help='Port to run the controller',
                         default=8082)
-    parser.add_argument('--min-nodes',
-                        type=int,
-                        default=1,
-                        help='Minimum nodes to keep running')
     args = parser.parse_args()
 
     # ======= Infra Provider =========
@@ -94,11 +91,17 @@ def get_server_ips():
     infra_provider = SkyPilotInfraProvider(args.task_yaml)
 
     # ======= Load Balancer =========
-    service_spec = SkyServiceSpec(args.task_yaml)
+    with open(args.task_yaml, 'r') as f:
+        task = yaml.safe_load(f)
+    if 'service' not in task:
+        raise ValueError('Task YAML must have a "service" section')
+    service_config = task['service']
+    service_spec = SkyServiceSpec.from_yaml_config(service_config)
     # Select the load balancing policy: RoundRobinLoadBalancer or LeastLoadedLoadBalancer
     load_balancer = RoundRobinLoadBalancer(
         infra_provider=infra_provider,
-        endpoint_path=service_spec.readiness_path)
+        endpoint_path=service_spec.readiness_path,
+        readiness_timeout=service_spec.readiness_timeout)
     # load_balancer = LeastLoadedLoadBalancer(n=5)
     # autoscaler = LatencyThresholdAutoscaler(load_balancer,
     #                                         upper_threshold=0.5,    # 500ms
@@ -106,14 +109,15 @@ def get_server_ips():
 
     # ======= Autoscaler =========
     # Create an autoscaler with the RequestRateAutoscaler policy. Thresholds are defined as requests per node in the defined interval.
-    autoscaler = RequestRateAutoscaler(infra_provider,
-                                       load_balancer,
-                                       frequency=5,
-                                       query_interval=60,
-                                       lower_threshold=0,
-                                       upper_threshold=1,
-                                       min_nodes=args.min_nodes,
-                                       cooldown=60)
+    autoscaler = RequestRateAutoscaler(
+        infra_provider,
+        load_balancer,
+        frequency=5,
+        min_nodes=service_spec.min_replica,
+        max_nodes=service_spec.max_replica,
+        upper_threshold=service_spec.qpm_upper_threshold,
+        lower_threshold=service_spec.qpm_lower_threshold,
+        cooldown=60)
 
     # ======= Controller =========
     # Create a controller object and run it.
diff --git a/sky/serve/examples/http_server/server.py b/sky/serve/examples/http_server/server.py
index 4ea616b148e..303b117d26d 100644
--- a/sky/serve/examples/http_server/server.py
+++ b/sky/serve/examples/http_server/server.py
@@ -3,7 +3,9 @@
 
 PORT = 8081
 
+
 class MyHttpRequestHandler(http.server.SimpleHTTPRequestHandler):
+
     def do_GET(self):
         # Return 200 for all paths
         # Therefore, readiness_probe will return 200 at path '/health'
@@ -23,6 +25,7 @@ def do_GET(self):
         self.wfile.write(bytes(html, 'utf8'))
         return
 
+
 Handler = MyHttpRequestHandler
 
 with socketserver.TCPServer(("", PORT), Handler) as httpd:
diff --git a/sky/serve/examples/http_server/task.yaml b/sky/serve/examples/http_server/task.yaml
index b82fbb29f75..d0fe866f259 100644
--- a/sky/serve/examples/http_server/task.yaml
+++ b/sky/serve/examples/http_server/task.yaml
@@ -9,4 +9,9 @@ run: python3 server.py
 
 service:
   port: 8081
-  readiness_probe: /health
+  readiness_probe:
+    path: /health
+    readiness_timeout: 12000
+  replica_policy:
+    min_replica: 1
+    max_replica: 1
diff --git a/sky/serve/load_balancers.py b/sky/serve/load_balancers.py
index 4c0c95c6ff7..90f94ceca41 100644
--- a/sky/serve/load_balancers.py
+++ b/sky/serve/load_balancers.py
@@ -12,12 +12,13 @@
 
 class LoadBalancer:
 
-    def __init__(self, infra_provider, endpoint_path, post_data=None):
+    def __init__(self, infra_provider, endpoint_path, readiness_timeout, post_data=None):
         self.available_servers = []
         self.request_count = 0
         self.request_timestamps = deque()
         self.infra_provider = infra_provider
         self.endpoint_path = endpoint_path
+        self.readiness_timeout = readiness_timeout
         self.post_data = post_data
 
     def increment_request_count(self, count=1):
@@ -37,7 +38,6 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.servers_queue = deque()
         self.first_unhealthy_time = {}
-        self.timeout = 18000
         logger.info(f'Endpoint path: {self.endpoint_path}')
 
     def probe_endpoints(self, endpoint_ips):
@@ -101,7 +101,7 @@ def probe_endpoint(endpoint_ip):
                 if server not in self.first_unhealthy_time:
                     self.first_unhealthy_time[server] = time.time()
                 elif time.time() - self.first_unhealthy_time[
-                        server] > self.timeout:  # cooldown before terminating a dead server to avoid hysterisis
+                        server] > self.readiness_timeout:  # cooldown before terminating a dead server to avoid hysterisis
                     servers_to_terminate.append(server)
             self.infra_provider.terminate_servers(servers_to_terminate)
 
diff --git a/sky/serve/redirector.py b/sky/serve/redirector.py
index 5c3df12c62c..3e130058abb 100644
--- a/sky/serve/redirector.py
+++ b/sky/serve/redirector.py
@@ -1,5 +1,6 @@
 import time
 import logging
+import yaml
 from collections import deque
 
 from sky.serve.common import SkyServiceSpec
@@ -113,7 +114,13 @@ def serve(self):
                         help='Controller address (ip:port).')
     args = parser.parse_args()
 
-    service_spec = SkyServiceSpec(args.task_yaml)
+    with open(args.task_yaml, 'r') as f:
+        task = yaml.safe_load(f)
+    if 'service' not in task:
+        raise ValueError('Task YAML must have a "service" section')
+    service_config = task['service']
+    service_spec = SkyServiceSpec.from_yaml_config(service_config)
+
     redirector = SkyServeRedirector(controller_url=args.controller_addr,
                                     service_spec=service_spec,
                                     port=args.port)
diff --git a/sky/task.py b/sky/task.py
index 2105d0feeda..2fadbc7395f 100644
--- a/sky/task.py
+++ b/sky/task.py
@@ -15,6 +15,7 @@
 from sky.backends import backend_utils
 from sky.data import storage as storage_lib
 from sky.data import data_utils
+from sky.serve import common
 from sky.skylet import constants
 from sky.utils import schemas
 from sky.utils import ux_utils
@@ -365,10 +366,12 @@ def from_yaml_config(
         resources = config.pop('resources', None)
         resources = sky.Resources.from_yaml_config(resources)
 
-        # FIXME: find a better way to exclude unused fields.
-        config.pop('service', None)
-
         task.set_resources({resources})
+
+        service = config.pop('service', None)
+        service = common.SkyServiceSpec.from_yaml_config(service)
+        task.service = service
+
         assert not config, f'Invalid task args: {config.keys()}'
         return task
 
diff --git a/sky/utils/schemas.py b/sky/utils/schemas.py
index 8126a97da9d..5c95edcd336 100644
--- a/sky/utils/schemas.py
+++ b/sky/utils/schemas.py
@@ -143,6 +143,52 @@ def get_storage_schema():
     }
 
 
+def get_service_schema():
+    return {
+        '$schema': 'http://json-schema.org/draft-07/schema#',
+        'type': 'object',
+        'required': ['port', 'readiness_probe', 'replica_policy'],
+        'additionalProperties': False,
+        'properties': {
+            'port': {
+                'type': 'integer',
+            },
+            'readiness_probe': {
+                'type': 'object',
+                'required': ['path', 'timeout'],
+                'additionalProperties': False,
+                'properties': {
+                    'path': {
+                        'type': 'string',
+                    },
+                    'readiness_timeout': {
+                        'type': 'number',
+                    },
+                }
+            },
+            'replica_policy': {
+                'type': 'object',
+                'required': ['min_replica'],
+                'additionalProperties': False,
+                'properties': {
+                    'min_replica': {
+                        'type': 'integer',
+                    },
+                    'max_replica': {
+                        'type': 'integer',
+                    },
+                    'qpm_upper_threshold': {
+                        'type': 'number',
+                    },
+                    'qpm_lower_threshold': {
+                        'type': 'number',
+                    },
+                }
+            }
+        }
+    }
+
+
 def get_task_schema():
     return {
         '$schema': 'https://json-schema.org/draft/2020-12/schema',
@@ -170,6 +216,10 @@ def get_task_schema():
             'file_mounts': {
                 'type': 'object',
             },
+            # service config is validated separately using SERVICE_SCHEMA
+            'service': {
+                'type': 'object',
+            },
             'setup': {
                 'type': 'string',
             },