Log Retrieval Server: The Security Station Approach to Log Monitoring…

1. Core Server Architecture

Just as a security station needs to verify its access cards and set monitoring limits before opening, our server validates its security badge (auth token) and sets maximum footage review limits before starting operations…

class LogRetrievalServer:
    def __init__(self, auth_token: Optional[str] = None, max_lines: int = 1000):
        self.log_dir = '/var/log'
        self.auth_token = auth_token
        self.max_lines = max_lines

        if not os.path.isdir(self.log_dir):
            raise ValueError(f"Invalid log directory: {self.log_dir}")

Technical Implementation Details:

• Server initialization with configurable parameters
• Early validation of log directory
• Optional authentication token
• Configurable line limit

Memory Considerations:

• Minimal memory footprint during initialization
• No file handles kept open
• No caching at server level

2. Log Reading Implementation

Like a guard reviewing security footage, we first verify we're accessing the correct surveillance zone (log directory) and prevent any attempts to access restricted areas (directory traversal)…

def read_log_file(self, filename, lines=None, filter_text=None):
    full_path = os.path.join(self.log_dir, filename)

    # Security: Prevent directory traversal
    if not os.path.abspath(full_path).startswith(os.path.abspath(self.log_dir)):
        raise PermissionError(f"Invalid file path: {filename}")

    lines_wanted = lines or self.max_lines
    matching_lines = []

Key Components:

1. Path Resolution and Security:

   os.path.abspath(full_path).startswith(os.path.abspath(self.log_dir))
   

   • Prevents directory traversal attacks
   • Handles symbolic links correctly
   • Normalizes paths for comparison