README
¶
rotoslog
This package implements a simple log file rotator handler for slog. It works out of the box using the standard JSONHandler (default) and TextHandler for output formatting, but supports custom handlers.
Example using default configuration:
package main
import (
"log/slog"
"github/alchemy/rotoslog"
)
func init() {
h, err := rotoslog.NewHandler(rotoslog.FilePrefix("msg-"))
if err != nil {
panic(err)
}
logger := slog.New(h)
slog.SetDefault(logger)
}
Example using custom slog-formatter handler:
package main
import (
"fmt"
"io"
"log/slog"
"os"
"testing"
"github/alchemy/rotoslog"
formatter "github.com/samber/slog-formatter"
)
func init() {
formatter1 := formatter.FormatByKey("pwd", func(v slog.Value) slog.Value {
return slog.StringValue("***********")
})
formatter2 := formatter.ErrorFormatter("error")
builder := func(w io.Writer, opts *slog.HandlerOptions) slog.Handler {
formattingMiddleware := formatter.NewFormatterHandler(formatter1, formatter2)
textHandler := NewTextHandler(w, opts)
return formattingMiddleware(textHandler)
}
h, err := rotoslog.NewHandler(rotoslog.HandlerBuilder(builder))
if err != nil {
panic(err)
}
logger := slog.New(h)
slog.SetDefault(logger)
}
Documentation
¶
Overview ¶
Package rotoslog provides a slog.Handler implementation that writes to a rotating set of files. Log file names have the following structure: <prefix>(<suffix>|<timestamp>)<extension>. When creating a new handler the user can set various options:
- LogDir: directory where log files are created (default: "log")
- FilePrefix: file name <prefix> (default: "")
- CurrentFileSuffix: current file name <suffix> (default : "current")
- FileExt: file <extension> (default: ".log")
- DateTimeLayout: <timestamp> layout to be used in calls to time.Time.Format (default: "20060102150405")
- MaxFileSize: size threshold that triggers rotation (default: 32M)
- MaxRotatedFiles: number of rotated files to keep (default: 8)
- HandlerOptions: slog.HandlerOptions (default: zero value)
- LogHandlerBuilder: a function that can build a slog.Handler used for formatting log data (default: [NewJSONHandler])
Index ¶
- Constants
- func CurrentFileSuffix(suffix string) optFun
- func DateTimeLayout(layout string) optFun
- func FileExt(ext string) optFun
- func FilePrefix(prefix string) optFun
- func HandlerOptions(opts slog.HandlerOptions) optFun
- func LogDir(dir string) optFun
- func LogHandlerBuilder[H slog.Handler](builder HandlerBuilder[H]) optFun
- func MaxFileSize(size uint64) optFun
- func MaxRotatedFiles(n uint64) optFun
- func NewHandler(options ...optFun) (slog.Handler, error)
- type HandlerBuilder
Examples ¶
Constants ¶
const ( DEFAULT_FILE_DIR = "log" DEFAULT_FILE_NAME_PREFIX = "" DEFAULT_CURRENT_FILE_SUFFIX = "current" DEFAULT_FILE_EXTENSION = ".log" DEFAULT_CURRENT_FILE_NAME = DEFAULT_FILE_NAME_PREFIX + DEFAULT_CURRENT_FILE_SUFFIX + DEFAULT_FILE_EXTENSION DEFAULT_FILE_DATE_FORMAT = "20060102150405" DEFAULT_MAX_FILE_SIZE = 32 * 1024 * 1024 DEFAULT_MAX_ROTATED_FILES = 8 DEFAULT_MAX_AGE = time.Duration(maxInt64) )
Variables ¶
This section is empty.
Functions ¶
func CurrentFileSuffix ¶ added in v0.2.0
func CurrentFileSuffix(suffix string) optFun
CurrentFileSuffix sets the current logging file suffix.
func DateTimeLayout ¶ added in v0.2.0
func DateTimeLayout(layout string) optFun
DateTimeLayout sets the timestamp layout used in rotated file names.
func FilePrefix ¶ added in v0.2.0
func FilePrefix(prefix string) optFun
FilePrefix sets the logging file prefix.
func HandlerOptions ¶ added in v0.2.0
func HandlerOptions(opts slog.HandlerOptions) optFun
HandlerOptions sets the slog.HandlerOptions for the handler.
func LogDir ¶ added in v0.2.0
func LogDir(dir string) optFun
LogDir sets the path to the logging directory
func LogHandlerBuilder ¶ added in v0.2.0
func LogHandlerBuilder[H slog.Handler](builder HandlerBuilder[H]) optFun
LogHandlerBuilder sets the HandlerBuilder used for formatting.
Example ¶
package main
import (
"context"
"fmt"
"io"
"log/slog"
"math/rand"
"github.com/alchemy/rotoslog"
formatter "github.com/samber/slog-formatter"
)
func randomLevel() slog.Level {
const min = -1
const max = 2
return slog.Level(4 * (rand.Intn(max-min+1) + min))
}
func main() {
const N = 10
formatter1 := formatter.FormatByKey("pwd", func(v slog.Value) slog.Value {
return slog.StringValue("***********")
})
formatter2 := formatter.ErrorFormatter("error")
builder := func(w io.Writer, opts *slog.HandlerOptions) slog.Handler {
formattingMiddleware := formatter.NewFormatterHandler(formatter1, formatter2)
textHandler := slog.NewTextHandler(w, opts)
return formattingMiddleware(textHandler)
}
h, err := rotoslog.NewHandler(rotoslog.LogHandlerBuilder(builder))
if err != nil {
panic(err)
}
logger := slog.New(h).With("N", N, "pwd", "123456")
slog.SetDefault(logger)
ctx := context.TODO()
for n := 0; n < N; n++ {
l := randomLevel()
if l == slog.LevelError {
err := fmt.Errorf("random error n° %d", n)
slog.Log(ctx, l, "tanto va la gatta al lardo che ci lascia lo zampino", "error", err)
continue
}
slog.Log(ctx, l, "tanto va la gatta al lardo che ci lascia lo zampino")
}
}
func MaxFileSize ¶ added in v0.2.0
func MaxFileSize(size uint64) optFun
MaxFileSize sets the size threshold that triggers file rotation. If size is 0 file rotation is disabled.
func MaxRotatedFiles ¶ added in v0.2.0
func MaxRotatedFiles(n uint64) optFun
MaxRotatedFiles sets the maximum number of rotated files. When the number of rotated files exceedes this number the oldest rotated file is deleted. Any value of n less than 1 is equivalent to passing 1.
Types ¶
type HandlerBuilder ¶
HandlerBuilder is a type representing functions used to create handlers to control formatting of logging data.
Source Files