package log_test import ( "errors" "flag" "os" "time" "github.com/rs/zerolog" "github.com/rs/zerolog/log" ) // setup would normally be an init() function, however, there seems // to be something awry with the testing framework when we set the // global Logger from an init() func setup() { // UNIX Time is faster and smaller than most timestamps // If you set zerolog.TimeFieldFormat to an empty string, // logs will write with UNIX time zerolog.TimeFieldFormat = "" // In order to always output a static time to stdout for these // examples to pass, we need to override zerolog.TimestampFunc // and log.Logger globals -- you would not normally need to do this zerolog.TimestampFunc = func() time.Time { return time.Date(2008, 1, 8, 17, 5, 05, 0, time.UTC) } log.Logger = zerolog.New(os.Stdout).With().Timestamp().Logger() } // Simple logging example using the Print function in the log package // Note that both Print and Printf are at the debug log level by default func ExamplePrint() { setup() log.Print("hello world") // Output: {"level":"debug","time":1199811905,"message":"hello world"} } // Simple logging example using the Printf function in the log package func ExamplePrintf() { setup() log.Printf("hello %s", "world") // Output: {"level":"debug","time":1199811905,"message":"hello world"} } // Example of a log with no particular "level" func ExampleLog() { setup() log.Log().Msg("hello world") // Output: {"time":1199811905,"message":"hello world"} } // Example of a log at a particular "level" (in this case, "debug") func ExampleDebug() { setup() log.Debug().Msg("hello world") // Output: {"level":"debug","time":1199811905,"message":"hello world"} } // Example of a log at a particular "level" (in this case, "info") func ExampleInfo() { setup() log.Info().Msg("hello world") // Output: {"level":"info","time":1199811905,"message":"hello world"} } // Example of a log at a particular "level" (in this case, "warn") func ExampleWarn() { setup() log.Warn().Msg("hello world") // Output: {"level":"warn","time":1199811905,"message":"hello world"} } // Example of a log at a particular "level" (in this case, "error") func ExampleError() { setup() log.Error().Msg("hello world") // Output: {"level":"error","time":1199811905,"message":"hello world"} } // Example of a log at a particular "level" (in this case, "fatal") func ExampleFatal() { setup() err := errors.New("A repo man spends his life getting into tense situations") service := "myservice" log.Fatal(). Err(err). Str("service", service). Msgf("Cannot start %s", service) // Outputs: {"level":"fatal","time":1199811905,"error":"A repo man spends his life getting into tense situations","service":"myservice","message":"Cannot start myservice"} } // TODO: Panic // This example uses command-line flags to demonstrate various outputs // depending on the chosen log level. func ExampleLevelFlag() { setup() debug := flag.Bool("debug", false, "sets log level to debug") flag.Parse() // Default level for this example is info, unless debug flag is present zerolog.SetGlobalLevel(zerolog.InfoLevel) if *debug { zerolog.SetGlobalLevel(zerolog.DebugLevel) } log.Debug().Msg("This message appears only when log level set to Debug") log.Info().Msg("This message appears when log level set to Debug or Info") if e := log.Debug(); e.Enabled() { // Compute log output only if enabled. value := "bar" e.Str("foo", value).Msg("some debug message") } // Output: {"level":"info","time":1199811905,"message":"This message appears when log level set to Debug or Info"} } // TODO: Output // TODO: With // TODO: Level // TODO: Sample // TODO: Hook // TODO: WithLevel // TODO: Ctx