feat: Refactor log-alert application into modular structure

- Introduced alerters package with base Alerter class and implementations for LogAlerter and GotifyAlerter.
- Created fetchers package with abstract LogFetcher class and implementations for FileLogFetcher, LokiLogFetcher, and ParseableLogFetcher.
- Added filters package with base Filter class and implementations for RegexpFilter and GeolocationFilter.
- Implemented rules package with base AlertRule class and SimpleAlertRule for alerting logic.
- Enhanced configuration handling with utilities for loading and validating JSON configuration.
- Updated logging setup for better logging management.
- Modified main application logic to utilize the new modular structure, improving maintainability and readability.
- Updated config.json and config.schema.json to reflect changes in alerting and fetching configurations.
- Added python-dateutil to requirements for date parsing functionality.

log-alert/fetchers/file.py

@@ -0,0 +1,81 @@
+"""File log fetcher implementation."""
+
+import logging
+import requests
+from typing import Dict, Any, List
+from dateutil.parser import parse
+
+from .base import LogFetcher
+
+logger = logging.getLogger("log-alert")
+
+
+class FileLogFetcher(LogFetcher):
+    """Concrete implementation for fetching logs from a file."""
+
+    type = "TAIL"
+
+    def __init__(self, config: Dict[str, Any]):
+        try:
+            self.file = open(config["file"], "r")
+        except FileNotFoundError:
+            logger.error(f"Log file not found: {config['file']}")
+            raise
+        self.position = 0  # To keep track of the last read position
+
+    def fetch_logs(self, filters: Dict[str, Any]) -> List[Dict[str, Any]]:
+        """Fetch logs from the file."""
+        logs = []
+
+        self.file.seek(self.position)  # Move to the last read position
+        while True:
+            self.position = self.file.tell()
+            line = self.file.readline()
+            if not line:
+                break  # End of file reached, exit loop
+
+            logger.debug(f"Read line: {line.strip()} at position {self.position}")
+
+            parts = line.strip().split(maxsplit=1)
+            timestamp_str, rest = parts[0], parts[1]
+
+            # Parse the timestamp string into a datetime object
+            dt = parse(timestamp_str)
+            # Convert to seconds since epoch
+            epoch_seconds = int(dt.timestamp())
+
+            log_entry = {"timestamp": epoch_seconds, "log": rest}
+
+            logs.append(log_entry)
+
+        return logs
+
+    def fetch_logs_time_range(self, filters: Dict[str, Any], start_time: int, end_time: int) -> List[Dict[str, Any]]:
+        """Fetch logs from the file within the specified time range."""
+        logs = []
+
+        self.file.seek(0)
+        while True:
+            line = self.file.readline()
+            if not line:
+                break  # End of file reached, exit loop
+
+            logger.debug(f"Read line: {line.strip()} at position {self.position}")
+
+            parts = line.strip().split(maxsplit=1)
+            timestamp_str, rest = parts[0], parts[1]
+
+            dt = parse(timestamp_str)
+            epoch_seconds = int(dt.timestamp())
+
+            if epoch_seconds < start_time:
+                continue
+            if epoch_seconds > end_time:
+                break
+
+            log_entry = {"timestamp": epoch_seconds, "log": rest}
+
+            logs.append(log_entry)
+
+        return logs
+