feat: add liveness-detector (#1920)

Co-authored-by: Tasko Olevski <[email protected]>

Author: SalimKayal

.github/workflows/ci.yml

@@ -38,6 +38,22 @@ jobs:
         cd git-https-proxy
         go test -v
 
+  test-liveness-detector:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install Pixi
+      uses: prefix-dev/[email protected]
+      with:
+        pixi-version: v0.24.2
+        manifest-path: ./liveness-detector/pyproject.toml
+        cache: true
+    - name: Test liveness detector
+      run: |
+        cd liveness-detector
+        pixi run lint-and-fix
+        pixi run test
+
   test-git-services:
     runs-on: ubuntu-latest
     steps:

liveness-detector/Dockerfile

@@ -0,0 +1,32 @@
+# SPDX-FileCopyrightText: 2024 Idiap Research Institute <[email protected]>
+# SPDX-FileContributor: Salim Kayal <[email protected]>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+FROM ghcr.io/prefix-dev/pixi:0.24.2-bookworm-slim AS build
+
+COPY pixi.lock /app/pixi.lock
+COPY pyproject.toml /app/pyproject.toml
+COPY liveness_detector /app/liveness_detector
+WORKDIR /app
+
+RUN pixi install -e default
+
+RUN <<EOF
+echo '#!/bin/bash' > /shell-hook.sh
+echo 'export PATH=/app/.pixi/envs/default/bin:${PATH}' >> /shell-hook.sh
+echo 'exec "$@"' >> /shell-hook.sh
+EOF
+
+FROM docker.io/debian:bookworm-slim AS production
+
+COPY --from=build /app/.pixi/envs/default /app/.pixi/envs/default
+COPY --from=build /app/liveness_detector /app/liveness_detector
+COPY --chmod=755 --from=build /shell-hook.sh /shell-hook.sh
+COPY --chmod=755 scripts/ /
+WORKDIR /app
+EXPOSE 8888
+
+ENTRYPOINT ["/shell-hook.sh"]
+
+CMD ["uvicorn", "liveness_detector:app", "--port", 8888]

liveness-detector/LICENSES/Apache-2.0.txt

@@ -0,0 +1,73 @@
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liveness-detector/README.md

@@ -0,0 +1,65 @@
+<!--
+ SPDX-FileCopyrightText: 2024 Idiap Research Institute <[email protected]>
+ SPDX-FileContributor: Salim Kayal <[email protected]>
+
+ SPDX-License-Identifier: Apache-2.0
+ -->
+
+# liveness-detector
+
+This module provides an endpoint to check whether the user is actively using his pod or not
+
+## Installation
+
+In order to kickstart the project ensure [pixi is installed](https://pixi.sh/latest/#installation) as we will be using it for environment and packaging management. Then to install the base dependencies and jupyter kernel for this environment run
+
+```bash
+$ pixi install
+```
+
+## Testing
+
+running the tests can be achieved by running the following command
+
+```bash
+$ pixi run test
+```
+
+## Running the server
+
+### shell
+
+Ensure the `PROJECT_SOURCE` environment variable is set then run
+
+```bash
+$ pixi run uvicorn liveness_detector:app --port 8888
+```
+
+### Docker
+
+build the image with
+
+```bash
+$ docker build --target=production --tag=${YOUR_TAG}
+```
+
+run it with
+
+```bash
+$ docker run -it --rm -v ${YOUR_LOCAL_PROJECT_PATH}:/project:Z -e PROJECT_SOURCE=/project -p 8888:8888
+${YOUR_TAG}
+```
+Connect to it with 
+
+```bash
+$ curl -sSL 127.0.0.1:8888/healthz
+```
+
+### As an init container
+
+mount the `/renku-liveness` folder in the init container and the environment container and run the
+`/entrypoint-init-container.sh` script
+
+then from the environment container, run the `/renku-liveness/entrypoint-hook.sh` with the 8888
+port forwarded.
+

liveness-detector/liveness_detector/__init__.py

@@ -0,0 +1,62 @@
+# SPDX-FileCopyrightText: 2024 Idiap Research Institute <[email protected]>
+# SPDX-FileContributor: Salim Kayal <[email protected]>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import asyncio
+
+from collections.abc import AsyncGenerator
+from contextlib import asynccontextmanager
+from os import environ, getloadavg
+from pathlib import Path
+
+from fastapi import FastAPI
+from pydantic import BaseModel
+
+from liveness_detector.activity_watcher import ActivityWatcher
+
+
+class HealthzResponse(BaseModel):
+    """
+    Represent a health check response containing system and activity information.
+
+    This model is used to structure the response for health check endpoints. It
+    provides details about the current system load average (`load_average`), timestamp
+    of the last file system activity within a monitored directory (`last_file_activity`),
+    and timestamp of the last pseudo-terminal activity (`last_tty_activity`).
+    """
+
+    load_average: float
+    last_file_activity: int
+    last_tty_activity: int
+
+
+watcher = ActivityWatcher(Path(environ["PROJECT_SOURCE"]))
+
+
+@asynccontextmanager
+async def manage_monitoring(app: FastAPI) -> AsyncGenerator[None, None]:
+    """Manage the monitoring of the last user activity."""
+    task = asyncio.create_task(watcher.run_inotify())
+    yield
+    task.cancel()
+
+
+app = FastAPI(lifespan=manage_monitoring)
+
+
+@app.get("/healthz", response_model=HealthzResponse)
+async def is_container_idle() -> HealthzResponse:
+    """
+    Check container idleness in the background and returns the status.
+
+    Returns
+    -------
+        JSON response with last activity timestamp.
+    """
+
+    return HealthzResponse(
+        load_average=getloadavg()[0],
+        last_tty_activity=watcher.last_tty_activity,
+        last_file_activity=watcher.last_file_activity,
+    )

liveness-detector/liveness_detector/activity_watcher.py

@@ -0,0 +1,79 @@
+# SPDX-FileCopyrightText: 2024 Idiap Research Institute <[email protected]>
+# SPDX-FileContributor: Salim Kayal <[email protected]>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+
+from pathlib import Path
+from time import time
+
+from asyncinotify import Inotify, Mask
+
+
+class ActivityWatcher:
+    """
+    A class to monitor activity within a directory and surrounding pseudo-terminals.
+
+    This class utilizes inotify to track file system events (create, delete, modify)
+    within the workspace directory and additionally monitors access events on pseudo-terminals
+    at `/dev/pts`. It maintains the last observed activity timestamp and provides methods
+    to add or remove watch descriptors. The class also offers an asynchronous `run` method
+    to continuously monitor activity and update the last activity timestamp.
+
+    Attributes
+    ----------
+      last_activity (float): Timestamp of the last observed activity.
+      workdir (str): The directory to monitor for file system events.
+    """
+
+    _DIRECTORY_CREATED = Mask.CREATE | Mask.ISDIR
+    _DIRECTORY_DELETED = Mask.DELETE | Mask.ISDIR
+
+    def __init__(self, workdir: Path):
+        """
+        Initialize the ActivityWatcher object.
+
+        Args:
+            workdir (str): The directory to monitor for file system events.
+        """
+        self._last_tty_activity = time()
+        self._last_file_activity = time()
+        self.workdir = workdir
+
+    @property
+    def last_file_activity(self) -> int:
+        return int(self._last_file_activity)
+
+    @property
+    def last_tty_activity(self) -> int:
+        return int(self._last_tty_activity)
+
+    async def run_inotify(self) -> None:
+        """
+        Continuously monitors activity within the specified directory and pseudo-terminals.
+
+        This asynchronous method utilizes inotify to monitor the configured directory and
+        pseudo-terminals. It continuously reads events and updates the `_last_activity`
+        timestamp. The method also handles directory creation and deletion events by
+        adding or removing watch descriptors accordingly.
+
+        This method should be called as an awaitable coroutine.
+        """
+        with Inotify() as inotify:
+            workdir_mask = Mask.MODIFY | Mask.CREATE | Mask.DELETE
+
+            inotify.add_watch(Path("/dev/pts"), Mask.ACCESS)
+            inotify.add_watch(self.workdir, workdir_mask)
+            for path_to_monitor, _, _ in self.workdir.walk():
+                if path_to_monitor.is_dir():
+                    inotify.add_watch(path_to_monitor, workdir_mask)
+
+            async for event in inotify:
+                if event.mask & Mask.ACCESS == Mask.ACCESS:
+                    self._last_tty_activity = time()
+                else:
+                    self._last_file_activity = time()
+                if event.mask & self._DIRECTORY_CREATED == self._DIRECTORY_CREATED:
+                    inotify.add_watch(event.watch.path / event.name, workdir_mask)
+                elif event.mask & self._DIRECTORY_DELETED == self._DIRECTORY_DELETED:
+                    inotify.rm_watch(event.watch)