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Zapr :zap:
==========
A [logr](https://github.com/go-logr/logr) implementation using
[Zap](https://github.com/uber-go/zap). Can also be used as
[slog](https://pkg.go.dev/log/slog) handler.
Usage
-----
Via logr:
```go
package main
import (
"fmt"
"go.uber.org/zap"
"github.com/go-logr/logr"
"github.com/go-logr/zapr"
)
func main() {
var log logr.Logger
zapLog, err := zap.NewDevelopment()
if err != nil {
panic(fmt.Sprintf("who watches the watchmen (%v)?", err))
}
log = zapr.NewLogger(zapLog)
log.Info("Logr in action!", "the answer", 42)
}
```
Via slog:
```
package main
import (
"fmt"
"log/slog"
"github.com/go-logr/logr/slogr"
"github.com/go-logr/zapr"
"go.uber.org/zap"
)
func main() {
var log *slog.Logger
zapLog, err := zap.NewDevelopment()
if err != nil {
panic(fmt.Sprintf("who watches the watchmen (%v)?", err))
}
log = slog.New(slogr.NewSlogHandler(zapr.NewLogger(zapLog)))
log.Info("Logr in action!", "the answer", 42)
}
```
Increasing Verbosity
--------------------
Zap uses semantically named levels for logging (`DebugLevel`, `InfoLevel`,
`WarningLevel`, ...). Logr uses arbitrary numeric levels. By default logr's
`V(0)` is zap's `InfoLevel` and `V(1)` is zap's `DebugLevel` (which is
numerically -1). Zap does not have named levels that are more verbose than
`DebugLevel`, but it's possible to fake it.
As of zap v1.19.0 you can do something like the following in your setup code:
```go
zc := zap.NewProductionConfig()
zc.Level = zap.NewAtomicLevelAt(zapcore.Level(-2))
z, err := zc.Build()
if err != nil {
// ...
}
log := zapr.NewLogger(z)
```
Zap's levels get more verbose as the number gets smaller and more important and
the number gets larger (`DebugLevel` is -1, `InfoLevel` is 0, `WarnLevel` is 1,
and so on).
The `-2` in the above snippet means that `log.V(2).Info()` calls will be active.
`-3` would enable `log.V(3).Info()`, etc. Note that zap's levels are `int8`
which means the most verbose level you can give it is -128. The zapr
implementation will cap `V()` levels greater than 127 to 127, so setting the
zap level to -128 really means "activate all logs".
Implementation Details
----------------------
For the most part, concepts in Zap correspond directly with those in logr.
Unlike Zap, all fields *must* be in the form of sugared fields --
it's illegal to pass a strongly-typed Zap field in a key position to any
of the logging methods (`Log`, `Error`).
The zapr `logr.LogSink` implementation also implements `logr.SlogHandler`. That
enables `slogr.NewSlogHandler` to provide a `slog.Handler` which just passes
parameters through to zapr. zapr handles special slog values (Group,
LogValuer), regardless of which front-end API is used.
|
