Added system checks to warn people of misconfigurations

src/paperless/__init__.py

@@ -0,0 +1 @@
+from .checks import paths_check

src/paperless/checks.py

@@ -0,0 +1,47 @@
+import os
+
+from django.core.checks import Error, register, Warning
+
+
+@register()
+def paths_check(app_configs, **kwargs):
+
+    check_messages = []
+
+    exists_message = "{} is set but doesn't exist."
+    exists_hint = "Create a directory at {}"
+    writeable_message = "{} is not writeable"
+    writeable_hint = (
+        "Set the permissions of {} to be writeable by the user running the "
+        "Paperless services"
+    )
+
+    directory = os.getenv("PAPERLESS_DBDIR")
+    if directory:
+        if not os.path.exists(directory):
+            check_messages.append(Error(
+                exists_message.format("PAPERLESS_DBDIR"),
+                exists_hint.format(directory)
+            ))
+        if not check_messages:
+            if not os.access(directory, os.W_OK | os.X_OK):
+                check_messages.append(Error(
+                    writeable_message.format("PAPERLESS_DBDIR"),
+                    writeable_hint.format(directory)
+                ))
+
+    directory = os.getenv("PAPERLESS_MEDIADIR")
+    if directory:
+        if not os.path.exists(directory):
+            check_messages.append(Error(
+                exists_message.format("PAPERLESS_MEDIADIR"),
+                exists_hint.format(directory)
+            ))
+        if not check_messages:
+            if not os.access(directory, os.W_OK | os.X_OK):
+                check_messages.append(Error(
+                    writeable_message.format("PAPERLESS_MEDIADIR"),
+                    writeable_hint.format(directory)
+                ))
+
+    return check_messages