Create logging target option and fallbacks

src/jcloud_deployment_server/api/logging.py

@@ -17,17 +17,50 @@ import jcloud_config_parser
 import logging
 import pathlib
 from dataclasses import dataclass
+from .exceptions import Fail
 
 __all__ = [
+    'LoggingInfo',
     'setup_logging'
 ]
 
 @dataclass
 class LoggingInfo:
     logger: logging.Logger
-    logfile: pathlib.Path
-    format: str
-    level: int
+    uvicorn_config: dict
+
+def _logfile_fallback_used(path: pathlib.Path) -> bool:
+    '''
+    Returns whether the fallback value for the logfile should be used.
+
+    :param path: The path to the logfile.
+    :type path: pathlib.Path
+
+    :return: Whether the fallback value should be used.
+    :rtype: bool
+    '''
+
+    # Path exists and is a directory -> invalid
+    if path.exists() and path.is_dir():
+        return True
+    
+    parent = path.parent or pathlib.Path('.')
+
+    # Parent directory missing -> try to create it
+    if not parent.exists():
+        try:
+            parent.mkdir(parents = True, exist_ok = True)
+        except OSError:
+            return True
+
+    # Check whether the path is writable.
+    try:
+        with open(path, 'a'):
+            pass
+    except (OSError, PermissionError):
+        return True
+    
+    return False
 
 def setup_logging(configuration: jcloud_config_parser.ini.INIConfiguration) -> LoggingInfo:
     '''
@@ -40,8 +73,22 @@ def setup_logging(configuration: jcloud_config_parser.ini.INIConfiguration) -> L
     :rtype: LoggingInfo
     '''
 
-    logfile = configuration.logging.logfile
-    if os.path.isdir(logfile) or not logfile:
+    fail_strict = configuration.logging.fail_strict.lower() in ('true', 'yes', 't', 'y')
+
+    logtarget = configuration.logging.logtarget
+
+    if logtarget not in ('file', 'stdout'):
+        if fail_strict:
+            raise Fail(f'\'{logtarget}\': invalid value for [logging].logtarget. Expected either \'file\' or \'stdout\'.')
+        logtarget = 'stdout'
+
+    if logtarget == 'file':
+        logfile = pathlib.Path(configuration.logging.logfile)
+        if _logfile_fallback_used(logfile):
+            if fail_strict:
+                raise Fail(f'\'{logfile}\': Cannot use as a log file.')
+            logtarget = 'stdout' # fallback to stdout
+    else:
         logfile = None
 
     loglevel = logging._nameToLevel.get(
@@ -54,17 +101,47 @@ def setup_logging(configuration: jcloud_config_parser.ini.INIConfiguration) -> L
     logging.basicConfig(level=loglevel, format=logging_format)
     logger = logging.getLogger('api')
     logger.propagate = False
-    logger.handlers = list()
 
     formatter = logging.Formatter(logging_format)
-    if logfile is not None:
-        logger_file_handler = logging.FileHandler(logfile)
-        logger_file_handler.setFormatter(formatter)
-        logger.addHandler(logger_file_handler)
+
+    if logtarget == 'file':
+        logger.handlers = list()
+        handler = logging.FileHandler(logfile)
+        handler.setFormatter(formatter)
+    else:
+        handler = logging.StreamHandler()
+        handler.setFormatter(formatter)
+    logger.addHandler(handler)
+
+    uvicorn_config = {
+        'version': 1,
+        'disable_existing_loggers': True,
+        'formatters': {
+            'uvicorn_formatter': {
+                'format': logging_format
+            }
+        },
+        'loggers': {
+            'uvicorn': {
+                'handlers': ['uvicorn_handler'],
+                'level': loglevel,
+                'propagate': False
+            },
+        },
+        'handlers': {
+            'uvicorn_handler': {
+                'class': 'logging.FileHandler',
+                'filename': logfile,
+                'formatter': 'uvicorn_formatter'
+            } if logtarget == 'file'
+            else {
+                'class': 'logging.StreamHandler',
+                'formatter': 'uvicorn_formatter'
+            }
+        }
+    }
 
     return LoggingInfo(
         logger,
-        logfile,
-        logging_format,
-        loglevel
+        uvicorn_config
     )

src/jcloud_deployment_server/api/main.py

@@ -50,27 +50,5 @@ def main():
         host = host,
         port = port,
         server_header = False,
-        log_config = {
-            'version': 1,
-            'disable_existing_loggers': True,
-            'handlers': {
-                'uvicorn_handler': {
-                    'class': 'logging.FileHandler',
-                    'filename': str(logger_info.logfile),
-                    'formatter': 'uvicorn_formatter',
-                },
-            },
-            'formatters': {
-                'uvicorn_formatter': {
-                    'format': logger_info.format
-                },
-            },
-            'loggers': {
-                'uvicorn': {
-                    'handlers': ['uvicorn_handler'],
-                    'level': logger_info.level,
-                    'propagate': False
-                },
-            },
-        }
+        log_config = logger_info.uvicorn_config
     )