Application settings

The sink integrates with Serilog.Settings.Configuration, so it can be configured from appsettings.json (or any other Microsoft.Extensions.Configuration provider) instead of in code. Because JSON has a limited type system, a few parameters are expressed differently than their CLR types — those are called out in the table below.

Parameters

Parameter	CLR type	JSON type	Default	Notes
uri	string	string	— (required)	Absolute http/https URI; validated at startup
labels	LokiLabel[]	array of objects	[]	Each object is { "key": "...", "value": "..." }
propertiesAsLabels	string[]	array of strings	[]	Property names promoted to stream labels
handleLogLevelAsLabel	bool	boolean	true	Adds the level label — see Visualizing log level in Grafana
credentialsLogin	string	string	null	Basic-auth user; pair with credentialsPassword
credentialsPassword	string	string	null	Basic-auth password
tenant	string	string	null	Sets the X-Scope-OrgID header — see Authentication and multi-tenancy
enrichTraceId	bool	boolean	false	See Trace and span enrichment
enrichSpanId	bool	boolean	false	See Trace and span enrichment
batchSizeLimit	int	integer	1000	Max events per HTTP POST
queueLimit	int	integer	50000	Bounded in-memory queue; newest events dropped when full
period	string	string	"00:00:01"	Flush interval, format hh:mm:ss (see notes)
eagerlyEmitFirstEvent	bool	boolean	true	Flush immediately on the first event
retryTimeLimit	string	string	"00:10:00"	Stop retrying a failed batch after this, format hh:mm:ss (see notes)
restrictedToMinimumLevel	LogEventLevel	string	Verbose	e.g. "Information" (see Enum.Parse)
textFormatter	ITextFormatter	string	LokiJsonTextFormatter	Type name "My.Namespace.MyType, MyAssembly" (see notes)
exceptionFormatter	ILokiExceptionFormatter	string	LokiExceptionFormatter	Type name "My.Namespace.MyType, MyAssembly" (see Custom exception formatting)
httpClient	HttpClient	—	null	Code-only; not configurable from JSON
httpMessageHandler	HttpMessageHandler	—	null	Code-only; not configurable from JSON

Notes

• period / retryTimeLimit are strings, not TimeSpan — format hh:mm:ss, e.g. "00:00:05". This keeps a single call signature that binds cleanly from JSON. Omit them to use the defaults.
• textFormatter / exceptionFormatter are bound by assembly-qualified type name and require a public parameterless constructor (LokiJsonTextFormatter and LokiExceptionFormatter both have one).
• httpClient / httpMessageHandler are runtime objects and can only be supplied in code (for example via IHttpClientFactory). See Custom HttpClient.

Full example

{
  "Serilog": {
    "Using": [
      "Serilog.Sinks.Grafana.Loki"
    ],
    "MinimumLevel": {
      "Default": "Debug"
    },
    "WriteTo": [
      {
        "Name": "GrafanaLoki",
        "Args": {
          "uri": "http://localhost:3100",
          "labels": [
            {
              "key": "app",
              "value": "web_app"
            }
          ],
          "propertiesAsLabels": [
            "app"
          ],
          "tenant": "my-tenant",
          "enrichTraceId": true,
          "batchSizeLimit": 500,
          "period": "00:00:02"
        }
      }
    ]
  }
}

Migrating from v8

Several argument names changed in v9 (for example credentials → credentialsLogin/credentialsPassword, batchPostingLimit → batchSizeLimit), and a few were removed. See Upgrading from v8 to v9.