使用crontab执行脚本时登录python

Question

I use the python's logging module to log what's happening in the script. It works perfectly if I run the script manually, but if I run it through crontab nothing gets logged. So there is probably some setting missing but I'm at loss where to find out which setting to change.

For reference this is the settings I use for the logging.

{
    "version": 1,
    "disable_existing_loggers": false,
    "formatters": {
        "simple": {
            "format": "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
        }
    },

    "handlers": {
        "console": {
            "class": "logging.StreamHandler",
            "level": "DEBUG",
            "formatter": "simple",
            "stream": "ext://sys.stdout"
        },

        "info_file_handler": {
            "class": "logging.handlers.RotatingFileHandler",
            "level": "INFO",
            "formatter": "simple",
            "filename": "info.log",
            "maxBytes": "10485760",
            "backupCount": "5",
            "encoding": "utf8"
        },

        "error_file_handler": {
            "class": "logging.handlers.RotatingFileHandler",
            "level": "ERROR",
            "formatter": "simple",
            "filename": "errors.log",
            "maxBytes": "10485760",
            "backupCount": "5",
            "encoding": "utf8"
        }
    },

    "loggers": {
        "my_module": {
            "level": "ERROR",
            "handlers": ["console"],
            "propagate": "no"
        }
    },

    "root": {
        "level": "INFO",
        "handlers": ["console", "info_file_handler", "error_file_handler"]
    }
}

Answer 1

Running things under Cron can be a little tricky:

1. it starts in the crontab user's $HOME directory. If there's an errors.log file there, it might not work. Check the permissions.

2. I've never seen ext://sys.stdout format before. Cron routes stdout to email, which tends not to work.

I suggest routing all messages to /tmp/myscript.log -- it's easier to check.