Add jsonschema validation (#6)

* Add JSON Schema validation for log-alert config and require jsonschema

* Add jsonschema dependency to requirements

* Enhance config loading with schema validation

Added JSON schema validation for configuration and improved error handling.

* Simplify token assignment and config loading

Refactor token retrieval and configuration loading.

log-alert/log-alert.py

@@ -1,5 +1,7 @@
+#!/usr/bin/env python3
 import argparse
 import json
+import jsonschema
 import os
 import re
 import requests
@@ -7,7 +9,7 @@ import sys
 import time
 from abc import ABC, abstractmethod
 from typing import Dict, Any, List, Optional
- 
+
 # Base Classes
 class LogFetcher(ABC):
     """Abstract base class for log fetchers."""
@@ -82,10 +84,15 @@ class RegexpFilter(Filter):
 
     def filter(self, log: Dict[str, Any]) -> Dict[str, Any]:
         match = re.search(self.match, log["log"])
-        print(f"Regex match for '{self.match}' in log: {match.groupdict()}")
         if match:
-            log["labels"].update(match.groupdict())
+            # Only call groupdict() when there is a match
+            groups = match.groupdict()
+            print(f"Regex match for '{self.match}' in log: {groups}")
+            if groups:
+                log.setdefault("labels", {}).update(groups)
             return log
+        # no match
+        print(f"Regex did not match for pattern '{self.match}' in log: {log.get('log')}")
         return None
 
 # Gotify Alert Manager
@@ -94,7 +101,7 @@ class GotifyAlertManager(AlertManager):
 
     def __init__(self, config: Dict[str, Any]):
         self.url = config["url"]
-        self.token = config["token"]
+        self.token = config.get("token")
 
     def send_alert(self, title: str, message: str) -> None:
         """Send an alert to Gotify."""
@@ -142,7 +149,7 @@ class AlertRule:
                     break
             if log_entry is None:
                 continue
-            message = self.alert_message.format_map(log_entry["labels"])
+            message = self.alert_message.format_map(log_entry.get("labels", {}))
             print(f"Sending message: {message}, with params: {log_entry}")
             self.alert_manager.send_alert(self.alert_title, message)
         self.last_run = self.next_run
@@ -162,12 +169,17 @@ class LogAlertApp:
         for manager in self.config["alert-managers"]:
             self.alert_managers[manager["name"]] = self._init_alert_manager(manager)
         self.alert_rules = [AlertRule(self.log_fetchers, self.alert_managers, rule) for rule in self.config["log-alerts"]]
-    
+
     def _load_config(self, config_path: str) -> Dict[str, Any]:
-        """Load the configuration from a JSON file."""
+        """Load the configuration from a JSON file and validate it with JSON Schema."""
         try:
             with open(config_path, 'r') as config_file:
-                return self._update_config_from_env(json.load(config_file))
+                # read JSON first
+                config = json.load(config_file)
+                # Perform schema validation if jsonschema is available
+                self._validate_config_with_schema(config)
+                # Update config to load env variable where required
+                return self._update_config_from_env(config)
         except FileNotFoundError:
             print(f"Error: Configuration file '{config_path}' not found.")
             sys.exit(1)
@@ -175,9 +187,26 @@ class LogAlertApp:
             print(f"Error: Invalid JSON in configuration file '{config_path}'.")
             sys.exit(1)
 
+    def _validate_config_with_schema(self, config: Dict[str, Any]) -> None:
+        """Validate a loaded config dict against log-alert/config.schema.json if jsonschema is installed."""
+        schema_path = os.path.join(os.path.dirname(__file__), 'config.schema.json')
+        try:
+            with open(schema_path, 'r') as sf:
+                schema = json.load(sf)
+            jsonschema.validate(instance=config, schema=schema)
+        except FileNotFoundError:
+            print(f"Warning: Schema file '{schema_path}' not found; skipping config validation.")
+        except jsonschema.exceptions.ValidationError as e:
+            print(f"Configuration validation error: {e.message}")
+            print("Detailed error:", e)
+            sys.exit(1)
+        except Exception as e:
+            print(f"Unexpected error while validating configuration: {e}")
+            sys.exit(1)
+
     def _update_config_from_env(self, config: Dict[str, Any]) -> Dict[str, Any]:
         """Update config values from environment variables if specified."""
-        for key, value in config.items():
+        for key, value in list(config.items()):
             if isinstance(value, dict):
                 config[key] = self._update_config_from_env(value)
             elif isinstance(value, list):
@@ -210,7 +239,7 @@ class LogAlertApp:
                 if time.time() >= rule.next_run:
                     rule.run()
             time.sleep(5)
- 
+
 def main():
     parser = argparse.ArgumentParser(description="Log and Alert Management Tool")
     parser.add_argument("--config", required=True, help="Path to the configuration file")