Minimalistic logging library for Go, heavily inspired by azer/logger and borrowing from chzyer/logex
$ go get github.com/danwakefield/kisslogFirst create an instance with a preferred name.
The returned Logger has three methods, all of which act like printf style functions.
package main
import "github.com/danwakefield/kisslog"
var log = kisslog.New("app")
func main() {
log.Info("Requesting an image at %s", "foo/bar.jpg")
log.Debug("I bet you wont see %s", "this")
log.Error("Failed to start, shutting down %d..%d..%d", 3, 2, 1)
}
// [20:15:00][INFO ][main.main:simple.go:8] app: Requesting an image at foo/bar.jpg
// [20:15:00][ERROR][main.main:simple.go:14] app: Failed to start, shutting down 3..2..1Structured information can be added by passing a kisslog.Attrs
instance as the last variable to the logging function
log.Info("I have just completed a task", kisslog.Attrs{
"foo": 1,
"bar": "baz",
})
// [20:18:33][INFO ][main.main:simple.go:12] app: I have just completed a task [ foo=1 bar=baz ]The default settings for kisslog are to log Info and Error for every logger to stderr, with output including the location of the log call.
By setting the LOG_LEVEL variable you can disable logging of certain methods.
The same can be achieved by setting kisslog.LogLevel
| ENV VAR | CODE | INFO |
|---|---|---|
LOG_LEVEL=DEBUG |
kisslog.LogLevel = kisslog.DebugLevel |
Allows Debug, Info and Error |
LOG_LEVEL=INFO |
kisslog.LogLevel = kisslog.InfoLevel |
Allows Info and Error |
LOG_LEVEL=ERROR |
kisslog.LogLevel = kisslog.ErrorLevel |
Allows Error |
LOG_LEVEL=DISABLE |
kisslog.LogLevel = kisslog.DisableLevel |
Allows no logging |
Loggers can be filtered by setting the LOG_ENABLED variable.
It can be managed programmatically using kisslog.EnableLogger and kisslog.DisableLogger.
Using any of these options disables logging from a logger unless it is explicitly enabled.
| ENV VAR | CODE | INFO |
|---|---|---|
LOG_ENABLED=foo |
kisslog.EnableLogger("foo") |
All loggers not 'enabled' explicitly are disabled |
| NA | kisslog.DisableLogger("foo") |
Loggers cannot be disabled with ENVARS |
JSON Output can be forced on and off by setting the LOG_JSON variable.
The kisslog.JSONOutput variable can be used for programmatic control.
If the variable is not set JSON output is used by default if stderr is not a terminal.
| ENV VAR | CODE | INFO |
|---|---|---|
LOG_JSON=TRUE |
kisslog.JSONOutput = true |
Can also use 1, on or enable to set ENVVAR |
LOG_JSON=FALSE |
kisslog.JSONOutput = false |
Can also use 0, off or disable to set ENVVAR |
LOG_JSON=TRUE go run example/simple.go
# {"time":"20:59:35","package":"app","level":"[INFO ]","trace":"[main.main:simple.go:8] ","msg":"Requesting an image at foo/bar.jpg"}
# {"time":"20:59:35","package":"app","level":"[INFO ]","trace":"[main.main:simple.go:12] ","msg":"I have just completed a task","attributes":{"bar":"baz","foo":1}}
# {"time":"20:59:35","package":"app","level":"[ERROR]","trace":"[main.main:simple.go:14] ","msg":"Failed to start, shutting down 3..2..1"}
By default kisslog adds the location of the log call to its output using runtime inspection.
This can be disabled using LOG_TRACE or kisslog.TraceFile
| ENV VAR | CODE | INFO |
|---|---|---|
LOG_TRACE=TRUE |
kisslog.TraceFile = true |
Can also use 1, on or enable to set ENVVAR |
LOG_TRACE=FALSE |
kisslog.TraceFile = false |
Can also use 0, off or disable to set ENVVAR |
LOG_TRACE=FALSE go run example/simple.go
# [16:23:37][INFO ]app: Requesting an image at foo/bar.jpg
# [16:23:37][INFO ]app: I have just completed a task [ foo=1 bar=baz ]
# [16:23:37][ERROR]app: Failed to start, shutting down 3..2..1
You can change the precision of the timestamp using LOG_TIMEFORMAT or kisslog.TimeFormat.
These both take values that golang's time package can parse.
| ENV VAR | CODE |
|---|---|
LOG_TIMEFORMAT=2006-01-02T15:04:05Z07:00 |
kisslog.TimeFormat = time.RFC3339 |
LOG_TIMEFORMAT=2006-01-02T15:04:05Z07:00 go run example/simple.go
# [2000-12-20T20:19:26+01:00][INFO ][main.main:simple.go:8] app: Requesting an image at foo/bar.jpg
# [2000-12-20T20:19:26+01:00][INFO ][main.main:simple.go:12] app: I have just completed a task [ foo=1 bar=baz ]
# [2000-12-20T20:19:26+01:00][ERROR][main.main:simple.go:14] app: Failed to start, shutting down 3..2..1
By default kisslog logs to os.Stderr.
This can be changed by calling kisslog.SetOutput() with an io.Writer
f, err := os.Create("foo.log")
if err != nil {
panic(err)
}
defer f.Close() // Ensure that the file is closed.
kisslog.SetOutput(f)f, err := os.OpenFile("foo.log", os.O_APPEND|os.O_WRONLY, 0666)
if err != nil {
panic(err)
}
defer f.Close()
kisslog.SetOutput(f)f, err := os.OpenFile("foo.log", os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
panic(err)
}
defer f.Close()
kisslog.SetOutput(f)