Serilog - keep only 7 latest files - serilog

Question

I use serilog and have the date as a part of my filename. This is an easy way to get to the file. Currently I am checking nightly events and I and just pick the last file in the morning.
Now, I only want to keep 7 days. This is was retainedFileCountLimit is for.
However that does not work as I want it too, as it might check for that specific filename.
How can I do this? (I had my own log system which deleted files older than a week)
Where are all serilog properties described? I am missing an overview of those.
//Add Serilog
string logFileName = HostingEnvironment.MapPath(#"~/new_" + DateTime.Now.ToString("yyyyMMdd") + ".log");
Log.Logger = new LoggerConfiguration()
.WriteTo.File(
path: logFileName,
retainedFileCountLimit: 7,
shared: true,
rollingInterval: RollingInterval.Day,
rollOnFileSizeLimit: true,
fileSizeLimitBytes: 123456,
flushToDiskInterval: TimeSpan.FromSeconds(5))
.CreateLogger();
Log.Information("Starting Serilog #1");

Answer 1

The File sink automatically includes the date in the file name - do not include DateTime.Now in the file name and let Serilog take care of that and you should get the retention that you expect.
var log = new LoggerConfiguration()
.WriteTo.File
(
"new_.txt", // <<<<<<<<<<<<<<<<<<<<<<
rollingInterval: RollingInterval.Day,
retainedFileCountLimit: 7,
// ...
)
.CreateLogger();
This will append the time period to the filename, creating a file set like:
new_20180631.txt
new_20180701.txt
new_20180702.txt
The documentation of the File sink is the repository on GitHub.