[App] Support for headless apps

requirements/app/base.txt

@@ -1,4 +1,4 @@
-lightning-cloud>=0.5.11
+lightning-cloud>=0.5.12
 packaging
 typing-extensions>=4.0.0, <=4.4.0
 deepdiff>=5.7.0, <=5.8.1

src/lightning_app/CHANGELOG.md

@@ -19,8 +19,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 ### Changed
 
 - The `MultiNode` components now warn the user when running with `num_nodes > 1` locally ([#15806](https://github.com/Lightning-AI/lightning/pull/15806))
+
 - Cluster creation and deletion now waits by default [#15458](https://github.com/Lightning-AI/lightning/pull/15458)
 
+- Running an app without a UI locally no longer opens the browser ([#15875](https://github.com/Lightning-AI/lightning/pull/15875))
+
+- Apps without UIs no longer activate the "Open App" button when running in the cloud ([#15875](https://github.com/Lightning-AI/lightning/pull/15875))
+
 
 ### Deprecated
 

src/lightning_app/cli/lightning_cli.py

@@ -2,13 +2,13 @@
 import shutil
 import sys
 from pathlib import Path
-from typing import Any, Tuple, Union
+from typing import Tuple, Union
 
 import arrow
 import click
 import inquirer
 import rich
-from lightning_cloud.openapi import Externalv1LightningappInstance, V1LightningappInstanceState, V1LightningworkState
+from lightning_cloud.openapi import V1LightningappInstanceState, V1LightningworkState
 from lightning_cloud.openapi.rest import ApiException
 from lightning_utilities.core.imports import RequirementCache
 from requests.exceptions import ConnectionError
@@ -48,15 +48,6 @@
 logger = Logger(__name__)
 
 
-def get_app_url(runtime_type: RuntimeType, *args: Any, need_credits: bool = False) -> str:
-    if runtime_type == RuntimeType.CLOUD:
-        lit_app: Externalv1LightningappInstance = args[0]
-        action = "?action=add_credits" if need_credits else ""
-        return f"{get_lightning_cloud_url()}/me/apps/{lit_app.id}{action}"
-    else:
-        return os.getenv("APP_SERVER_HOST", "http://127.0.0.1:7501/view")
-
-
 def main() -> None:
     # Check environment and versions if not in the cloud
     if "LIGHTNING_APP_STATE_URL" not in os.environ:
@@ -269,10 +260,6 @@ def _run_app(
 
     secrets = _format_input_env_variables(secret)
 
-    def on_before_run(*args: Any, **kwargs: Any) -> None:
-        if open_ui and not without_server:
-            click.launch(get_app_url(runtime_type, *args, **kwargs))
-
     click.echo("Your Lightning App is starting. This won't take long.")
 
     # TODO: Fixme when Grid utilities are available.
@@ -284,7 +271,6 @@ def on_before_run(*args: Any, **kwargs: Any) -> None:
         start_server=not without_server,
         no_cache=no_cache,
         blocking=blocking,
-        on_before_run=on_before_run,
         name=name,
         env_vars=env_vars,
         secrets=secrets,

src/lightning_app/runners/cloud.py

@@ -7,8 +7,9 @@
 from dataclasses import dataclass
 from pathlib import Path
 from textwrap import dedent
-from typing import Any, Callable, List, Optional, Union
+from typing import Any, List, Optional, Union
 
+import click
 from lightning_cloud.openapi import (
     Body3,
     Body4,
@@ -56,12 +57,13 @@
     ENABLE_MULTIPLE_WORKS_IN_NON_DEFAULT_CONTAINER,
     ENABLE_PULLING_STATE_ENDPOINT,
     ENABLE_PUSHING_STATE_ENDPOINT,
+    get_lightning_cloud_url,
 )
 from lightning_app.runners.backends.cloud import CloudBackend
 from lightning_app.runners.runtime import Runtime
 from lightning_app.source_code import LocalSourceCodeDir
 from lightning_app.storage import Drive, Mount
-from lightning_app.utilities.app_helpers import Logger
+from lightning_app.utilities.app_helpers import _is_headless, Logger
 from lightning_app.utilities.cloud import _get_project
 from lightning_app.utilities.dependency_caching import get_hash
 from lightning_app.utilities.load_app import load_app_from_file
@@ -192,9 +194,9 @@ class CloudRuntime(Runtime):
 
     def dispatch(
         self,
-        on_before_run: Optional[Callable] = None,
         name: str = "",
         cluster_id: str = None,
+        open_ui: bool = True,
         **kwargs: Any,
     ) -> None:
         """Method to dispatch and run the :class:`~lightning_app.core.app.LightningApp` in the cloud."""
@@ -405,6 +407,7 @@ def dispatch(
                 local_source=True,
                 dependency_cache_key=app_spec.dependency_cache_key,
                 user_requested_flow_compute_config=app_spec.user_requested_flow_compute_config,
+                is_headless=_is_headless(self.app),
             )
 
             # create / upload the new app release
@@ -464,12 +467,12 @@ def dispatch(
             logger.error(e.body)
             sys.exit(1)
 
-        if on_before_run:
-            on_before_run(lightning_app_instance, need_credits=not has_sufficient_credits)
-
         if lightning_app_instance.status.phase == V1LightningappInstanceState.FAILED:
             raise RuntimeError("Failed to create the application. Cannot upload the source code.")
 
+        if open_ui:
+            click.launch(self._get_app_url(lightning_app_instance, not has_sufficient_credits))
+
         if cleanup_handle:
             cleanup_handle()
 
@@ -538,6 +541,11 @@ def load_app_from_file(cls, filepath: str) -> "LightningApp":
             app = LightningApp(EmptyFlow())
         return app
 
+    @staticmethod
+    def _get_app_url(lightning_app_instance: Externalv1LightningappInstance, need_credits: bool = False) -> str:
+        action = "?action=add_credits" if need_credits else ""
+        return f"{get_lightning_cloud_url()}/me/apps/{lightning_app_instance.id}{action}"
+
 
 def _create_mount_drive_spec(work_name: str, mount: Mount) -> V1LightningworkDrives:
     if mount.protocol == "s3://":

src/lightning_app/runners/multiprocess.py

@@ -1,15 +1,17 @@
 import multiprocessing
 import os
 from dataclasses import dataclass
-from typing import Any, Callable, Optional, Union
+from typing import Any, Union
+
+import click
 
 from lightning_app.api.http_methods import _add_tags_to_api, _validate_api
 from lightning_app.core.api import start_server
 from lightning_app.core.constants import APP_SERVER_IN_CLOUD
 from lightning_app.runners.backends import Backend
 from lightning_app.runners.runtime import Runtime
 from lightning_app.storage.orchestrator import StorageOrchestrator
-from lightning_app.utilities.app_helpers import is_overridden
+from lightning_app.utilities.app_helpers import _is_headless, is_overridden
 from lightning_app.utilities.commands.base import _commands_to_api, _prepare_commands
 from lightning_app.utilities.component import _set_flow_context, _set_frontend_context
 from lightning_app.utilities.load_app import extract_metadata_from_app
@@ -29,7 +31,7 @@ class MultiProcessRuntime(Runtime):
     backend: Union[str, Backend] = "multiprocessing"
     _has_triggered_termination: bool = False
 
-    def dispatch(self, *args: Any, on_before_run: Optional[Callable] = None, **kwargs: Any):
+    def dispatch(self, *args: Any, open_ui: bool = True, **kwargs: Any):
         """Method to dispatch and run the LightningApp."""
         try:
             _set_flow_context()
@@ -101,8 +103,8 @@ def dispatch(self, *args: Any, on_before_run: Optional[Callable] = None, **kwarg
                 # wait for server to be ready
                 has_started_queue.get()
 
-            if on_before_run:
-                on_before_run(self, self.app)
+            if open_ui and not _is_headless(self.app):
+                click.launch(self._get_app_url())
 
             # Connect the runtime to the application.
             self.app.connect(self)
@@ -125,3 +127,7 @@ def terminate(self):
             for port in ports:
                 disable_port(port)
         super().terminate()
+
+    @staticmethod
+    def _get_app_url() -> str:
+        return os.getenv("APP_SERVER_HOST", "http://127.0.0.1:7501/view")

src/lightning_app/runners/singleprocess.py

@@ -1,9 +1,13 @@
 import multiprocessing as mp
-from typing import Any, Callable, Optional
+import os
+from typing import Any
+
+import click
 
 from lightning_app.core.api import start_server
 from lightning_app.core.queues import QueuingSystem
 from lightning_app.runners.runtime import Runtime
+from lightning_app.utilities.app_helpers import _is_headless
 from lightning_app.utilities.load_app import extract_metadata_from_app
 
 
@@ -13,7 +17,7 @@ class SingleProcessRuntime(Runtime):
     def __post_init__(self):
         pass
 
-    def dispatch(self, *args, on_before_run: Optional[Callable] = None, **kwargs: Any):
+    def dispatch(self, *args, open_ui: bool = True, **kwargs: Any):
         """Method to dispatch and run the LightningApp."""
         queue = QueuingSystem.SINGLEPROCESS
 
@@ -42,8 +46,8 @@ def dispatch(self, *args, on_before_run: Optional[Callable] = None, **kwargs: An
             # wait for server to be ready.
             has_started_queue.get()
 
-        if on_before_run:
-            on_before_run()
+        if open_ui and not _is_headless(self.app):
+            click.launch(self._get_app_url())
 
         try:
             self.app._run()
@@ -52,3 +56,7 @@ def dispatch(self, *args, on_before_run: Optional[Callable] = None, **kwargs: An
             raise
         finally:
             self.terminate()
+
+    @staticmethod
+    def _get_app_url() -> str:
+        return os.getenv("APP_SERVER_HOST", "http://127.0.0.1:7501/view")

src/lightning_app/utilities/app_helpers.py

@@ -22,6 +22,7 @@
 
 import lightning_app
 from lightning_app.utilities.exceptions import LightningAppStateException
+from lightning_app.utilities.tree import breadth_first
 
 if TYPE_CHECKING:
     from lightning_app.core.app import LightningApp
@@ -527,3 +528,15 @@ def _should_dispatch_app() -> bool:
         and not bool(int(os.getenv("LIGHTNING_DISPATCHED", "0")))
         and "LIGHTNING_APP_STATE_URL" not in os.environ
     )
+
+
+def _is_headless(app: "LightningApp") -> bool:
+    """Utility which returns True if the given App has no ``Frontend`` objects or URLs exposed through
+    ``configure_layout``."""
+    if app.frontends:
+        return False
+    for component in breadth_first(app.root, types=(lightning_app.LightningFlow,)):
+        for entry in component._layout:
+            if "target" in entry:
+                return False
+    return True

src/lightning_app/utilities/layout.py

@@ -41,8 +41,9 @@ def _collect_layout(app: "lightning_app.LightningApp", flow: "lightning_app.Ligh
         # When running in the cloud, the frontend code will construct the URL based on the flow name
         return flow._layout
     elif isinstance(layout, _MagicMockJsonSerializable):
-        # Do nothing
-        pass
+        # The import was mocked, we assume it is a `Frontend`
+        app.frontends.setdefault(flow.name, "mock")
+        return flow._layout
     elif isinstance(layout, dict):
         layout = _collect_content_layout([layout], flow)
     elif isinstance(layout, (list, tuple)) and all(isinstance(item, dict) for item in layout):
@@ -108,8 +109,9 @@ def _collect_content_layout(layout: List[Dict], flow: "lightning_app.LightningFl
                 entry["content"] = ""
                 entry["target"] = ""
         elif isinstance(entry["content"], _MagicMockJsonSerializable):
-            # Do nothing
-            pass
+            # The import was mocked, so we just record dummy content
+            entry["content"] = "mock"
+            entry["target"] = "mock"
         else:
             m = f"""
             A dictionary returned by `{flow.__class__.__name__}.configure_layout()` contains an unsupported entry.

tests/tests_app/cli/test_cli.py

@@ -4,45 +4,15 @@
 
 import pytest
 from click.testing import CliRunner
-from lightning_cloud.openapi import Externalv1LightningappInstance
 
 from lightning_app import __version__
-from lightning_app.cli.lightning_cli import _main, get_app_url, login, logout, run
+from lightning_app.cli.lightning_cli import _main, login, logout, run
 from lightning_app.cli.lightning_cli_create import create, create_cluster
 from lightning_app.cli.lightning_cli_delete import delete, delete_cluster
 from lightning_app.cli.lightning_cli_list import get_list, list_apps, list_clusters
-from lightning_app.runners.runtime_type import RuntimeType
 from lightning_app.utilities.exceptions import _ApiExceptionHandler
 
 
-@pytest.mark.parametrize(
-    "runtime_type, extra_args, lightning_cloud_url, expected_url",
-    [
-        (
-            RuntimeType.CLOUD,
-            (Externalv1LightningappInstance(id="test-app-id"),),
-            "https://b975913c4b22eca5f0f9e8eff4c4b1c315340a0d.staging.lightning.ai",
-            "https://b975913c4b22eca5f0f9e8eff4c4b1c315340a0d.staging.lightning.ai/me/apps/test-app-id",
-        ),
-        (
-            RuntimeType.CLOUD,
-            (Externalv1LightningappInstance(id="test-app-id"),),
-            "http://localhost:9800",
-            "http://localhost:9800/me/apps/test-app-id",
-        ),
-        (RuntimeType.SINGLEPROCESS, tuple(), "", "http://127.0.0.1:7501/view"),
-        (RuntimeType.SINGLEPROCESS, tuple(), "http://localhost:9800", "http://127.0.0.1:7501/view"),
-        (RuntimeType.MULTIPROCESS, tuple(), "", "http://127.0.0.1:7501/view"),
-        (RuntimeType.MULTIPROCESS, tuple(), "http://localhost:9800", "http://127.0.0.1:7501/view"),
-    ],
-)
-def test_start_target_url(runtime_type, extra_args, lightning_cloud_url, expected_url):
-    with mock.patch(
-        "lightning_app.cli.lightning_cli.get_lightning_cloud_url", mock.MagicMock(return_value=lightning_cloud_url)
-    ):
-        assert get_app_url(runtime_type, *extra_args) == expected_url
-
-
 @pytest.mark.parametrize("command", [_main, run, get_list, create, delete])
 def test_commands(command):
     runner = CliRunner()

tests/tests_app/runners/test_cloud.py

@@ -13,6 +13,7 @@
     Body8,
     Body9,
     Externalv1Cluster,
+    Externalv1LightningappInstance,
     Gridv1ImageSpec,
     IdGetBody,
     V1BuildSpec,
@@ -1414,3 +1415,25 @@ def run(self):
 
     with pytest.raises(ValueError, match="You requested a custom base image for the Work with name"):
         _validate_build_spec_and_compute(Work())
+
+
+@pytest.mark.parametrize(
+    "lightning_app_instance, lightning_cloud_url, expected_url",
+    [
+        (
+            Externalv1LightningappInstance(id="test-app-id"),
+            "https://b975913c4b22eca5f0f9e8eff4c4b1c315340a0d.staging.lightning.ai",
+            "https://b975913c4b22eca5f0f9e8eff4c4b1c315340a0d.staging.lightning.ai/me/apps/test-app-id",
+        ),
+        (
+            Externalv1LightningappInstance(id="test-app-id"),
+            "http://localhost:9800",
+            "http://localhost:9800/me/apps/test-app-id",
+        ),
+    ],
+)
+def test_get_app_url(lightning_app_instance, lightning_cloud_url, expected_url):
+    with mock.patch(
+        "lightning_app.runners.cloud.get_lightning_cloud_url", mock.MagicMock(return_value=lightning_cloud_url)
+    ):
+        assert CloudRuntime._get_app_url(lightning_app_instance) == expected_url

tests/tests_app/runners/test_multiprocess.py

@@ -1,6 +1,8 @@
 from unittest import mock
 from unittest.mock import Mock
 
+import pytest
+
 from lightning_app import LightningApp, LightningFlow, LightningWork
 from lightning_app.frontend import StaticWebFrontend, StreamlitFrontend
 from lightning_app.runners import MultiProcessRuntime
@@ -81,3 +83,14 @@ def run(self):
 def test_multiprocess_runtime_sets_context():
     """Test that the runtime sets the global variable COMPONENT_CONTEXT in Flow and Work."""
     MultiProcessRuntime(LightningApp(ContxtFlow())).dispatch()
+
+
+@pytest.mark.parametrize(
+    "expected_url",
+    [
+        "http://127.0.0.1:7501/view",
+        "http://127.0.0.1:7501/view",
+    ],
+)
+def test_get_app_url(expected_url):
+    assert MultiProcessRuntime._get_app_url() == expected_url