Service fails silently when logfile path doesn't exist

[eloekset]

Similar to #335 when the logfile setting refers to a folder that doesn't exist, the service fails to start, but there's no error in application log telling why it failed to start.

To reproduce

1. Edit the .conf file to have a logfile setting as follows:
   logfile "../Logs/redis_log.txt"
2. Make sure there's no Logs folder at the level above the Redis folder.
3. Start the service, and you'll see this message:
   
4. To verify that the missing Logs folder is the actual cause, just create that folder and try to start the service again. This time it should start.

Expected behavior

A. Automatically create new folders if the path is valid.
B. Log an error to the application log indicating what's wrong.

[cwkr]

The redis.windows-service.conf file in the zip distribution contains logfile "Logs/redis_log.txt" as configured logfile, which does not exist. So Services created with redis-server.exe --service-install redis.windows-service.conf --loglevel verbose will simply not start until logfile is changed or a Logs folder was created. +1 from me

[enricogior]

Hi @wi2kl3r
good point, we should change the default log location in redis.windows-service.conf in order to avoid the issue in the first place.
Thank you.

[dkerwood]

Furthermore, with the logfile config value, can we add the ability to log events to a filename that corresponds to the date of the entry - i..e 20170303_redis_server.log -> 20171231_redis_server.log. (Linux version has this feature) This will allow log files to be smaller, and data from older log file to be found easily or removed if no longer required. redis.conf file could do with some comments about permissions of the logfile folder, and regarding use of / or \ in path names.