Adjust ElasticsearchSinkOptions.NumberOfShards in SeriLog not working in .Net core - elasticsearch

Question

I have a problem when setting NumberOfShards for ElasticSearch while writing log by SeriLog.
I do config for Serilog like this in .Net Core
.WriteTo.Elasticsearch(new ElasticsearchSinkOptions(new Uri(config.ElasticConnectionUrl))
{
AutoRegisterTemplate = true,
IndexFormat = config.ElasticIndex + "-{0:yyyy.MM.dd}",
NumberOfShards = 2,
NumberOfReplicas = 0
}));
But when I query the setting of the created Index in Kibana, the numberOfShards still 5 (default value). Even for NumberOfReplicas won't affect.
I am using ELK stack to trace logs.
Is anyone khow why?

Answer 1

You can do Serilog configuration in code, or in appSettings.json configuration. If you are doing this:
var loggerConfiguration = new LoggerConfiguration()
.ReadFrom.Configuration(configuration) // <= this reads from config
.WriteTo.Elasticsearch(new ElasticsearchSinkOptions(new Uri(config.ElasticConnectionUrl))
{
AutoRegisterTemplate = true,
IndexFormat = config.ElasticIndex + "-{0:yyyy.MM.dd}",
NumberOfShards = 2,
NumberOfReplicas = 0
})); // this gets partially ignored
And you have the following configuration file:
"Serilog": {
"MinimumLevel": "Debug",
"WriteTo": [
{
"Name": "Elasticsearch",
"Args": {
"nodeUris": "http://localhost:9100"
}
}
]
}
If you have left the index format empty in the JSON file, then you'll probably have an index named like "log-stash-{0:YYYY-MM-DD}", but you'll also have the one you've added in code. Same goes for the URIs. You might have two if you've added one in in the JSON sink WriteTo and in the ElasticsearchSinkOptions in code.
Config as JSON or as code. Choose one (sadly). See this for further information: https://github.com/serilog/serilog-sinks-elasticsearch/issues/180
I was looking to have a way to have a default configuration in code, that could potentially be overwritten using the configuration file, since I'm trying to create a generic opinionated IHostBuilder for our company various APIs, but Serilog is playing nicely. My solution is to move the Sinks config out of the Serilog config section, and define it separately, and load it myself, (in the same format - string Name, Args Dictionary<string, string>), and then create the config manually in code.