Add HEALTH_CHECK['DISK_USAGE_PATH'] Setting

docs/settings.md

@@ -75,11 +75,28 @@ HEALTH_CHECK = {
 With the above default settings, warnings will be reported when disk
 utilization exceeds 90% or available memory drops below 100 MB.
 
+By default `psutil` assume the disk to check is available at `/` path.
+To use a different disk e.g. when the app is deployed in a
+container but the relevant disk is the host disk, update the dictionary
+above to include `DISK_USAGE_PATH` setting.
+
+```python
+HEALTH_CHECK = {
+    # existing settings
+    "DISK_USAGE_PATH": "/host/",  # string path to disk
+}
+```
+
 ### `DISK_USAGE_MAX`
 
 Specify the desired disk utilization threshold, in percent. When disk
 usage exceeds the specified value, a warning will be reported.
 
+### `DISK_USAGE_PATH`
+
+Specify the path to the desired disk for which utilization needs to be
+checked.
+
 ### `MEMORY_MIN`
 
 Specify the desired memory utilization threshold, in megabytes. When

health_check/conf.py

@@ -2,6 +2,7 @@
 
 HEALTH_CHECK = getattr(settings, "HEALTH_CHECK", {})
 HEALTH_CHECK.setdefault("DISK_USAGE_MAX", 90)
+HEALTH_CHECK.setdefault("DISK_USAGE_PATH", "/")
 HEALTH_CHECK.setdefault("MEMORY_MIN", 100)
 HEALTH_CHECK.setdefault("WARNINGS_AS_ERRORS", True)
 HEALTH_CHECK.setdefault("SUBSETS", {})

health_check/contrib/psutil/backends.py

@@ -10,13 +10,14 @@
 host = socket.gethostname()
 
 DISK_USAGE_MAX = HEALTH_CHECK["DISK_USAGE_MAX"]
+DISK_USAGE_PATH = HEALTH_CHECK["DISK_USAGE_PATH"]
 MEMORY_MIN = HEALTH_CHECK["MEMORY_MIN"]
 
 
 class DiskUsage(BaseHealthCheckBackend):
     def check_status(self):
         try:
-            du = psutil.disk_usage("/")
+            du = psutil.disk_usage(DISK_USAGE_PATH)
             if DISK_USAGE_MAX and du.percent >= DISK_USAGE_MAX:
                 raise ServiceWarning(f"{host} {du.percent}% disk usage exceeds {DISK_USAGE_MAX}%")
         except ValueError as e:

pyproject.toml

@@ -61,6 +61,7 @@ test = [
   "pytest-cov",
   "pytest-django",
   "celery",
+  "psutil",
   "redis",
   "django-storages",
   "boto3",

tests/test_psutil.py

@@ -0,0 +1,43 @@
+from collections import namedtuple
+from unittest import mock
+
+import pytest
+
+from health_check.contrib.psutil.backends import DiskUsage
+
+# psutil.disk_usage() returns a namedtuple
+sdiskusage = namedtuple("sdiskusage", ("total", "used", "free", "percent"))
+
+
+def mock_disk_usage(path):
+    """Mock function to simulate psutil.disk_usage() in a container/host environment."""
+    if path == "/":
+        # Default path (container) with high disk space
+        return sdiskusage(total=100, used=97, free=3, percent=97)
+    elif path == "/host/":
+        # Custom path (host) with low disk usage
+        return sdiskusage(total=100, used=5, free=95, percent=5)
+    else:
+        # No other disk in the system
+        raise FileNotFoundError(f"No such file or directory: '{path}'")
+
+
+@mock.patch("health_check.contrib.psutil.backends.psutil.disk_usage", mock_disk_usage)
+class TestDiskUsage:
+    def test_default_path(self):
+        du = DiskUsage()
+        du.run_check()
+        assert du.errors
+        assert "97% disk usage exceeds 90%" in str(du.errors[0])
+
+    @mock.patch.multiple("health_check.contrib.psutil.backends", DISK_USAGE_PATH="/host/")
+    def test_custom_path_when_valid(self):
+        du = DiskUsage()
+        du.run_check()
+        assert not du.errors
+
+    @mock.patch.multiple("health_check.contrib.psutil.backends", DISK_USAGE_PATH="*NOT A PATH*")
+    def test_custom_path_when_invalid(self):
+        du = DiskUsage()
+        with pytest.raises(FileNotFoundError):
+            du.run_check()

tests/testapp/settings.py

@@ -28,6 +28,7 @@
     "health_check.storage",
     "health_check.contrib.celery",
     "health_check.contrib.migrations",
+    "health_check.contrib.psutil",
     "health_check.contrib.celery_ping",
     "health_check.contrib.s3boto_storage",
     "health_check.contrib.db_heartbeat",