introduce config checking infrastructure

owrx/__main__.py

@@ -1,6 +1,6 @@
 from http.server import HTTPServer
 from owrx.http import RequestHandler
-from owrx.config import PropertyManager
+from owrx.config import PropertyManager, Config
 from owrx.feature import FeatureDetector
 from owrx.sdr import SdrService
 from socketserver import ThreadingMixIn
@@ -12,6 +12,7 @@ from owrx.pskreporter import PskReporter
 import logging
 
 logging.basicConfig(level=logging.DEBUG, format="%(asctime)s - %(name)s - %(levelname)s - %(message)s")
+logger = logging.getLogger(__name__)
 
 
 class ThreadedHttpServer(ThreadingMixIn, HTTPServer):
@@ -32,13 +33,22 @@ Author contact info:    Jakob Ketterl, DD5JFK <dd5jfk@darc.de>
 
     pm = PropertyManager.getSharedInstance().loadConfig()
 
+    configErrors = Config.validateConfig()
+    if configErrors:
+        logger.error(
+            "your configuration contains errors. please address the following errors:"
+        )
+        for e in configErrors:
+            logger.error(e)
+        return
+
     featureDetector = FeatureDetector()
     if not featureDetector.is_available("core"):
-        print(
+        logger.error(
             "you are missing required dependencies to run openwebrx. "
             "please check that the following core requirements are installed:"
         )
-        print(", ".join(featureDetector.get_requirements("core")))
+        logger.error(", ".join(featureDetector.get_requirements("core")))
         return
 
     # Get error messages about unknown / unavailable features as soon as possible

owrx/config.py

@@ -1,5 +1,6 @@
 import importlib.util
 import logging
+import os
 
 logger = logging.getLogger(__name__)
 
@@ -147,3 +148,36 @@ class PropertyManager(object):
             except FileNotFoundError:
                 pass
         raise ConfigNotFoundException("no usable config found! please make sure you have a valid configuration file!")
+
+
+class ConfigError(object):
+    def __init__(self, key, message):
+        self.key = key
+        self.message = message
+
+    def __str__(self):
+        return "Configuration Error (key: {0}): {1}".format(self.key, self.message)
+
+
+class Config:
+    @staticmethod
+    def validateConfig():
+        pm = PropertyManager.getSharedInstance()
+        errors = [
+            Config.checkTempDirectory(pm)
+        ]
+
+        return [e for e in errors if e is not None]
+
+    @staticmethod
+    def checkTempDirectory(pm: PropertyManager):
+        key = "temporary_directory"
+        if not key in pm or pm[key] is None:
+            return ConfigError(key, "temporary directory is not set")
+        if not os.path.exists(pm[key]):
+            return ConfigError(key, "temporary directory doesn't exist")
+        if not os.path.isdir(pm[key]):
+            return ConfigError(key, "temporary directory path is not a directory")
+        if not os.access(pm[key], os.W_OK):
+            return ConfigError(key, "temporary directory is not writable")
+        return None