From 77c172b823b64ebface655681ab0749b9d2f7081 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ra=C3=BAl=20Benencia?= Date: Fri, 13 Apr 2018 16:30:31 -0700 Subject: First public commit --- vendor/github.com/go-kit/kit/log/README.md | 147 +++++++++++++++++++++++++++++ 1 file changed, 147 insertions(+) create mode 100644 vendor/github.com/go-kit/kit/log/README.md (limited to 'vendor/github.com/go-kit/kit/log/README.md') diff --git a/vendor/github.com/go-kit/kit/log/README.md b/vendor/github.com/go-kit/kit/log/README.md new file mode 100644 index 0000000..7222f80 --- /dev/null +++ b/vendor/github.com/go-kit/kit/log/README.md @@ -0,0 +1,147 @@ +# package log + +`package log` provides a minimal interface for structured logging in services. +It may be wrapped to encode conventions, enforce type-safety, provide leveled +logging, and so on. It can be used for both typical application log events, +and log-structured data streams. + +## Structured logging + +Structured logging is, basically, conceding to the reality that logs are +_data_, and warrant some level of schematic rigor. Using a stricter, +key/value-oriented message format for our logs, containing contextual and +semantic information, makes it much easier to get insight into the +operational activity of the systems we build. Consequently, `package log` is +of the strong belief that "[the benefits of structured logging outweigh the +minimal effort involved](https://www.thoughtworks.com/radar/techniques/structured-logging)". + +Migrating from unstructured to structured logging is probably a lot easier +than you'd expect. + +```go +// Unstructured +log.Printf("HTTP server listening on %s", addr) + +// Structured +logger.Log("transport", "HTTP", "addr", addr, "msg", "listening") +``` + +## Usage + +### Typical application logging + +```go +w := log.NewSyncWriter(os.Stderr) +logger := log.NewLogfmtLogger(w) +logger.Log("question", "what is the meaning of life?", "answer", 42) + +// Output: +// question="what is the meaning of life?" answer=42 +``` + +### Contextual Loggers + +```go +func main() { + var logger log.Logger + logger = log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr)) + logger = log.With(logger, "instance_id", 123) + + logger.Log("msg", "starting") + NewWorker(log.With(logger, "component", "worker")).Run() + NewSlacker(log.With(logger, "component", "slacker")).Run() +} + +// Output: +// instance_id=123 msg=starting +// instance_id=123 component=worker msg=running +// instance_id=123 component=slacker msg=running +``` + +### Interact with stdlib logger + +Redirect stdlib logger to Go kit logger. + +```go +import ( + "os" + stdlog "log" + kitlog "github.com/go-kit/kit/log" +) + +func main() { + logger := kitlog.NewJSONLogger(kitlog.NewSyncWriter(os.Stdout)) + stdlog.SetOutput(kitlog.NewStdlibAdapter(logger)) + stdlog.Print("I sure like pie") +} + +// Output: +// {"msg":"I sure like pie","ts":"2016/01/01 12:34:56"} +``` + +Or, if, for legacy reasons, you need to pipe all of your logging through the +stdlib log package, you can redirect Go kit logger to the stdlib logger. + +```go +logger := kitlog.NewLogfmtLogger(kitlog.StdlibWriter{}) +logger.Log("legacy", true, "msg", "at least it's something") + +// Output: +// 2016/01/01 12:34:56 legacy=true msg="at least it's something" +``` + +### Timestamps and callers + +```go +var logger log.Logger +logger = log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr)) +logger = log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller) + +logger.Log("msg", "hello") + +// Output: +// ts=2016-01-01T12:34:56Z caller=main.go:15 msg=hello +``` + +## Supported output formats + +- [Logfmt](https://brandur.org/logfmt) ([see also](https://blog.codeship.com/logfmt-a-log-format-thats-easy-to-read-and-write)) +- JSON + +## Enhancements + +`package log` is centered on the one-method Logger interface. + +```go +type Logger interface { + Log(keyvals ...interface{}) error +} +``` + +This interface, and its supporting code like is the product of much iteration +and evaluation. For more details on the evolution of the Logger interface, +see [The Hunt for a Logger Interface](http://go-talks.appspot.com/github.com/ChrisHines/talks/structured-logging/structured-logging.slide#1), +a talk by [Chris Hines](https://github.com/ChrisHines). +Also, please see +[#63](https://github.com/go-kit/kit/issues/63), +[#76](https://github.com/go-kit/kit/pull/76), +[#131](https://github.com/go-kit/kit/issues/131), +[#157](https://github.com/go-kit/kit/pull/157), +[#164](https://github.com/go-kit/kit/issues/164), and +[#252](https://github.com/go-kit/kit/pull/252) +to review historical conversations about package log and the Logger interface. + +Value-add packages and suggestions, +like improvements to [the leveled logger](https://godoc.org/github.com/go-kit/kit/log/level), +are of course welcome. Good proposals should + +- Be composable with [contextual loggers](https://godoc.org/github.com/go-kit/kit/log#With), +- Not break the behavior of [log.Caller](https://godoc.org/github.com/go-kit/kit/log#Caller) in any wrapped contextual loggers, and +- Be friendly to packages that accept only an unadorned log.Logger. + +## Benchmarks & comparisons + +There are a few Go logging benchmarks and comparisons that include Go kit's package log. + +- [imkira/go-loggers-bench](https://github.com/imkira/go-loggers-bench) includes kit/log +- [uber-common/zap](https://github.com/uber-common/zap), a zero-alloc logging library, includes a comparison with kit/log -- cgit v1.2.3