fix: log file configurable via env var, log error on permission issue

Author: rwxd

README.md

@@ -326,7 +326,7 @@ index_html: |
 ```bash
 LOG_LEVEL=DEBUG       # Optional: DEBUG, INFO, WARNING, ERROR (default: DEBUG)
 LOG_FORMAT=json       # Optional: "text" (default) or "json" for structured logging
-LOG_FILE=/var/log/app.log  # Optional: Enable file logging to specified path (default: disabled, logs to stderr only)
+LOG_FILE=/var/log/app.log  # Optional: Log file path (default: "log"), set to "false" to disable file logging
 LISTEN_HOST=0.0.0.0   # Optional: Host to bind to (default: *)
 LISTEN_PORT=8000      # Optional: Port to listen on (default: 8000)
 ```

powerdns_api_proxy/logging.py

@@ -99,13 +99,16 @@ def audit(
 logger: AuditLogger = logging.getLogger("powerdns_api_proxy")  # type: ignore
 logger.addHandler(default_stream_handler)
 
-LOG_FILE = getenv("LOG_FILE")
-if LOG_FILE:
-    file_handler = logging.handlers.RotatingFileHandler(
-        filename=LOG_FILE, maxBytes=1000**2 * 100, backupCount=5
-    )
-    file_handler.setLevel("DEBUG")
-    file_handler.setFormatter(default_formatter)
-    logger.addHandler(file_handler)
+LOG_FILE = getenv("LOG_FILE", "log")
+if LOG_FILE and LOG_FILE.lower() != "false":
+    try:
+        file_handler = logging.handlers.RotatingFileHandler(
+            filename=LOG_FILE, maxBytes=1000**2 * 100, backupCount=5
+        )
+        file_handler.setLevel(LOG_LEVEL)
+        file_handler.setFormatter(default_formatter)
+        logger.addHandler(file_handler)
+    except OSError as e:
+        logger.error(f"Failed to enable file logging to {LOG_FILE}: {e}")
 
 logger.setLevel("DEBUG")