[Services] Add default probes if model is set

src/dstack/_internal/cli/services/configurators/run.py

@@ -354,7 +354,7 @@ def interpolate_env(self, conf: RunConfigurationT):
                     password=interpolator.interpolate_or_error(conf.registry_auth.password),
                 )
             if isinstance(conf, ServiceConfiguration):
-                for probe in conf.probes:
+                for probe in conf.probes or []:
                     for header in probe.headers:
                         header.value = interpolator.interpolate_or_error(header.value)
                     if probe.url:

src/dstack/_internal/core/models/configurations.py

@@ -56,6 +56,8 @@
 DEFAULT_PROBE_METHOD = "get"
 MAX_PROBE_URL_LEN = 2048
 DEFAULT_REPLICA_GROUP_NAME = "0"
+DEFAULT_MODEL_PROBE_TIMEOUT = 30
+DEFAULT_MODEL_PROBE_URL = "/v1/chat/completions"
 
 
 class RunConfigurationType(str, Enum):
@@ -851,9 +853,9 @@ class ServiceConfigurationParams(CoreModel):
     ] = None
     rate_limits: Annotated[list[RateLimit], Field(description="Rate limiting rules")] = []
     probes: Annotated[
-        list[ProbeConfig],
+        Optional[list[ProbeConfig]],
         Field(description="List of probes used to determine job health"),
-    ] = []
+    ] = None  # None = omitted (may get default when model is set); [] = explicit empty
 
     replicas: Annotated[
         Optional[Union[List[ReplicaGroup], Range[int]]],
@@ -895,7 +897,9 @@ def validate_rate_limits(cls, v: list[RateLimit]) -> list[RateLimit]:
         return v
 
     @validator("probes")
-    def validate_probes(cls, v: list[ProbeConfig]) -> list[ProbeConfig]:
+    def validate_probes(cls, v: Optional[list[ProbeConfig]]) -> Optional[list[ProbeConfig]]:
+        if v is None:
+            return v
         if has_duplicates(v):
             # Using a custom validator instead of Field(unique_items=True) to avoid Pydantic bug:
             # https://github.com/pydantic/pydantic/issues/3765
@@ -932,6 +936,35 @@ def validate_replicas(
                 )
         return v
 
+    @root_validator()
+    def set_default_probes_for_model(cls, values):
+        model = values.get("model")
+        probes = values.get("probes")
+        if model is not None and probes is None:
+            body = orjson.dumps(
+                {
+                    "model": model.name,
+                    "messages": [{"role": "user", "content": "hi"}],
+                    "max_tokens": 1,
+                }
+            ).decode("utf-8")
+            values["probes"] = [
+                ProbeConfig(
+                    type="http",
+                    method="post",
+                    url=DEFAULT_MODEL_PROBE_URL,
+                    headers=[
+                        HTTPHeaderSpec(name="Content-Type", value="application/json"),
+                    ],
+                    body=body,
+                    timeout=DEFAULT_MODEL_PROBE_TIMEOUT,
+                )
+            ]
+        elif probes is None:
+            # Probes omitted and model not set: normalize to empty list for downstream.
+            values["probes"] = []
+        return values
+
     @root_validator()
     def validate_scaling(cls, values):
         scaling = values.get("scaling")

src/dstack/_internal/server/services/jobs/configurators/base.py

@@ -394,7 +394,7 @@ def _service_port(self) -> Optional[int]:
 
     def _probes(self) -> list[ProbeSpec]:
         if isinstance(self.run_spec.configuration, ServiceConfiguration):
-            return list(map(_probe_config_to_spec, self.run_spec.configuration.probes))
+            return list(map(_probe_config_to_spec, self.run_spec.configuration.probes or []))
         return []
 
 

src/dstack/_internal/server/services/runs/spec.py

@@ -94,13 +94,13 @@ def validate_run_spec_and_set_defaults(
             raise ServerClientError(
                 "Scheduled services with autoscaling to zero are not supported"
             )
-        if len(run_spec.configuration.probes) > settings.MAX_PROBES_PER_JOB:
+        if len(run_spec.configuration.probes or []) > settings.MAX_PROBES_PER_JOB:
             raise ServerClientError(
                 f"Cannot configure more than {settings.MAX_PROBES_PER_JOB} probes"
             )
         if any(
             p.timeout is not None and p.timeout > settings.MAX_PROBE_TIMEOUT
-            for p in run_spec.configuration.probes
+            for p in (run_spec.configuration.probes or [])
         ):
             raise ServerClientError(
                 f"Probe timeout cannot be longer than {settings.MAX_PROBE_TIMEOUT}s"

src/tests/_internal/core/models/test_configurations.py

@@ -5,6 +5,8 @@
 from dstack._internal.core.errors import ConfigurationError
 from dstack._internal.core.models.common import RegistryAuth
 from dstack._internal.core.models.configurations import (
+    DEFAULT_MODEL_PROBE_TIMEOUT,
+    DEFAULT_MODEL_PROBE_URL,
     DevEnvironmentConfigurationParams,
     RepoSpec,
     parse_run_configuration,
@@ -13,6 +15,49 @@
 
 
 class TestParseConfiguration:
+    def test_service_model_sets_default_probes_when_probes_omitted(self):
+        conf = {
+            "type": "service",
+            "commands": ["python3 -m http.server"],
+            "port": 8000,
+            "model": "meta-llama/Meta-Llama-3.1-8B-Instruct",
+        }
+        parsed = parse_run_configuration(conf)
+        assert len(parsed.probes) == 1
+        probe = parsed.probes[0]
+        assert probe.type == "http"
+        assert probe.method == "post"
+        assert probe.url == DEFAULT_MODEL_PROBE_URL
+        assert probe.timeout == DEFAULT_MODEL_PROBE_TIMEOUT
+        assert len(probe.headers) == 1
+        assert probe.headers[0].name == "Content-Type"
+        assert probe.headers[0].value == "application/json"
+        assert "meta-llama/Meta-Llama-3.1-8B-Instruct" in (probe.body or "")
+        assert "max_tokens" in (probe.body or "")
+
+    def test_service_model_does_not_override_explicit_probes(self):
+        conf = {
+            "type": "service",
+            "commands": ["python3 -m http.server"],
+            "port": 8000,
+            "model": "meta-llama/Meta-Llama-3.1-8B-Instruct",
+            "probes": [{"type": "http", "url": "/health"}],
+        }
+        parsed = parse_run_configuration(conf)
+        assert len(parsed.probes) == 1
+        assert parsed.probes[0].url == "/health"
+
+    def test_service_model_explicit_empty_probes_no_default(self):
+        conf = {
+            "type": "service",
+            "commands": ["python3 -m http.server"],
+            "port": 8000,
+            "model": "meta-llama/Meta-Llama-3.1-8B-Instruct",
+            "probes": [],
+        }
+        parsed = parse_run_configuration(conf)
+        assert len(parsed.probes) == 0
+
     def test_services_replicas_and_scaling(self):
         def test_conf(replicas: Any, scaling: Optional[Any] = None):
             conf = {