Log Filter

A LogFilter represents function/conditions for log filtering.

Following filter

import zio.LogLevel
import zio.logging.LogFilter

val filter = LogFilter.logLevelByName(
    LogLevel.Debug,
    "io.netty" -> LogLevel.Info, 
    "io.grpc.netty" -> LogLevel.Info,
    "org.my.**.ServiceX" -> LogLevel.Trace, // glob-like (any paths) filter
    "org.my.X*Layers" -> LogLevel.Info // glob-like (single or partial path) filter
)

will use the Debug log level for everything except for log events with the logger name prefixed by either List("io", "netty") or List("io", "grpc", "netty") or List("org", "my", "**", "ServiceX") or List("org", "my", "X*Layers"). Logger name is extracted from log annotation or zio.Trace.

LogFilter.filter returns a version of zio.ZLogger that only logs messages when this filter is satisfied.

Configuration

the configuration for filter (zio.logging.LogFilter.LogLevelByNameConfig) has the following configuration structure:

{
    # LogLevel values: ALL, FATAL, ERROR, WARN, INFO, DEBUG, TRACE, OFF
    
    # root LogLevel, default value: INFO
    rootLevel = DEBUG 
    
    # LogLevel configurations for specific logger names, or prefixes, default value: empty
    mappings {
      "io.netty" = "INFO"
      "io.grpc.netty" = "INFO"
    }
}

this configuration is equivalent to following:

import zio.LogLevel
import zio.logging.LogFilter

val config =
  LogFilter.LogLevelByNameConfig(LogLevel.Debug, Map("io.netty" -> LogLevel.Info, "io.grpc.netty" -> LogLevel.Info))

val filter = LogFilter.logLevelByName(config)