🚀 Install

go get github.com/samber/slog-multi

Warning

Use this library carefully, log processing can be very costly (!)

💡 Usage

Broadcast:slogmulti.Fanout()

import (    slogmulti"github.com/samber/slog-multi""log/slog")funcmain() {logstash,_:=net.Dial("tcp","logstash.acme:4242")// use github.com/netbrain/goautosocket for auto-reconnectstderr:=os.Stderrlogger:=slog.New(slogmulti.Fanout(slog.NewJSONHandler(logstash,&slog.HandlerOptions{}),// pass to first handler: logstash over tcpslog.NewTextHandler(stderr,&slog.HandlerOptions{}),// then to second handler: stderr// ...        ),    )logger.With(slog.Group("user",slog.String("id","user-123"),slog.Time("created_at",time.Now()),            ),        ).With("environment","dev").With("error",fmt.Errorf("an error")).Error("A message")}

time=2023-04-10T14:00:0.000000+00:00 level=ERROR msg="A message" user.id=user-123 user.created_at=2023-04-10T14:00:0.000000+00:00 environment=dev error="an error"

{"time":"2023-04-10T14:00:0.000000+00:00","level":"ERROR","msg":"A message","user":{"id":"user-123","created_at":"2023-04-10T14:00:0.000000+00:00"},"environment":"dev","error":"an error"}

Routing:slogmulti.Router()

import (    slogmulti"github.com/samber/slog-multi"    slogslack"github.com/samber/slog-slack""log/slog")funcmain() {slackChannelUS:= slogslack.Option{Level:slog.LevelError,WebhookURL:"xxx",Channel:"supervision-us"}.NewSlackHandler()slackChannelEU:= slogslack.Option{Level:slog.LevelError,WebhookURL:"xxx",Channel:"supervision-eu"}.NewSlackHandler()slackChannelAPAC:= slogslack.Option{Level:slog.LevelError,WebhookURL:"xxx",Channel:"supervision-apac"}.NewSlackHandler()logger:=slog.New(slogmulti.Router().Add(slackChannelUS,recordMatchRegion("us")).Add(slackChannelEU,recordMatchRegion("eu")).Add(slackChannelAPAC,recordMatchRegion("apac")).Handler(),    )logger.With("region","us").With("pool","us-east-1").Error("Server desynchronized")}funcrecordMatchRegion(regionstring)func(ctx context.Context,r slog.Record)bool {returnfunc(ctx context.Context,r slog.Record)bool {ok:=falser.Attrs(func(attr slog.Attr)bool {ifattr.Key=="region"&&attr.Value.Kind()==slog.KindString&&attr.Value.String()==region {ok=truereturnfalse            }returntrue        })returnok    }}

Failover:slogmulti.Failover()

import ("net"    slogmulti"github.com/samber/slog-multi""log/slog")funcmain() {// ncat -l 1000 -k// ncat -l 1001 -k// ncat -l 1002 -k// list AZs// use github.com/netbrain/goautosocket for auto-reconnectlogstash1,_:=net.Dial("tcp","logstash.eu-west-3a.internal:1000")logstash2,_:=net.Dial("tcp","logstash.eu-west-3b.internal:1000")logstash3,_:=net.Dial("tcp","logstash.eu-west-3c.internal:1000")logger:=slog.New(slogmulti.Failover()(            slog.HandlerOptions{}.NewJSONHandler(logstash1,nil),// send to this instance first            slog.HandlerOptions{}.NewJSONHandler(logstash2,nil),// then this instance in case of failure            slog.HandlerOptions{}.NewJSONHandler(logstash3,nil),// and finally this instance in case of double failure        ),    )logger.With(slog.Group("user",slog.String("id","user-123"),slog.Time("created_at",time.Now()),            ),        ).With("environment","dev").With("error",fmt.Errorf("an error")).Error("A message")}

Load balancing:slogmulti.Pool()

import ("net"    slogmulti"github.com/samber/slog-multi""log/slog")funcmain() {// ncat -l 1000 -k// ncat -l 1001 -k// ncat -l 1002 -k// list AZs// use github.com/netbrain/goautosocket for auto-reconnectlogstash1,_:=net.Dial("tcp","logstash.eu-west-3a.internal:1000")logstash2,_:=net.Dial("tcp","logstash.eu-west-3b.internal:1000")logstash3,_:=net.Dial("tcp","logstash.eu-west-3c.internal:1000")logger:=slog.New(slogmulti.Pool()(// a random handler will be picked            slog.HandlerOptions{}.NewJSONHandler(logstash1,nil),            slog.HandlerOptions{}.NewJSONHandler(logstash2,nil),            slog.HandlerOptions{}.NewJSONHandler(logstash3,nil),        ),    )logger.With(slog.Group("user",slog.String("id","user-123"),slog.Time("created_at",time.Now()),            ),        ).With("environment","dev").With("error",fmt.Errorf("an error")).Error("A message")}

Recover errors:slog.RecoverHandlerError()

import (slogformatter"github.com/samber/slog-formatter"slogmulti"github.com/samber/slog-multi""log/slog")recovery:=slogmulti.RecoverHandlerError(func(ctx context.Context,record slog.Record,errerror) {// will be called only if subsequent handlers fail or return an errorlog.Println(err.Error())    },)sink:=NewSinkHandler(...)logger:=slog.New(slogmulti.Pipe(recovery).Handler(sink),)err:=fmt.Errorf("an error")logger.Error("a message",slog.Any("very_private_data","abcd"),slog.Any("user",user),slog.Any("err",err))// outputs:// time=2023-04-10T14:00:0.000000+00:00 level=ERROR msg="a message" error.message="an error" error.type="*errors.errorString" user="John doe" very_private_data="********"

Chaining:slogmulti.Pipe()

funcmain() {// first middleware: format go `error` type into an object {error: "*myCustomErrorType", message: "could not reach https://a.b/c"}errorFormattingMiddleware:=slogmulti.NewHandleInlineMiddleware(errorFormattingMiddleware)// second middleware: remove PIIgdprMiddleware:=NewGDPRMiddleware()// final handlersink:=slog.NewJSONHandler(os.Stderr,&slog.HandlerOptions{})logger:=slog.New(slogmulti.Pipe(errorFormattingMiddleware).Pipe(gdprMiddleware).// ...Handler(sink),    )logger.With(slog.Group("user",slog.String("id","user-123"),slog.String("email","user-123"),slog.Time("created_at",time.Now()),            ),        ).With("environment","dev").Error("A message",slog.String("foo","bar"),slog.Any("error",fmt.Errorf("an error")),        )}

{"time":"2023-04-10T14:00:0.000000+00:00","level":"ERROR","msg":"A message","user":{"id":"*******","email":"*******","created_at":"*******"    },"environment":"dev","foo":"bar","error":{"type":"*myCustomErrorType","message":"an error"    }}

Custom middleware

typeMiddlewarefunc(slog.Handler) slog.Handler

Inline handler

mdw:=slogmulti.NewHandleInlineHandler(// simulate "Handle()"func(ctx context.Context,groups []string,attrs []slog.Attr,record slog.Record)error {// [...]returnnil    },)

mdw:=slogmulti.NewInlineHandler(// simulate "Enabled()"func(ctx context.Context,groups []string,attrs []slog.Attr,level slog.Level)bool {// [...]returntrue    },// simulate "Handle()"func(ctx context.Context,groups []string,attrs []slog.Attr,record slog.Record)error {// [...]returnnil    },)

Inline middleware

// hook `logger.Enabled` methodmdw:=slogmulti.NewEnabledInlineMiddleware(func(ctx context.Context,level slog.Level,nextfunc(context.Context, slog.Level)bool)bool{// [...]returnnext(ctx,level)})

// hook `logger.Handle` methodmdw:=slogmulti.NewHandleInlineMiddleware(func(ctx context.Context,record slog.Record,nextfunc(context.Context, slog.Record)error)error {// [...]returnnext(ctx,record)})

// hook `logger.WithAttrs` methodmdw:=slogmulti.NewWithAttrsInlineMiddleware(func(attrs []slog.Attr,nextfunc([]slog.Attr) slog.Handler) slog.Handler{// [...]returnnext(attrs)})

// hook `logger.WithGroup` methodmdw:=slogmulti.NewWithGroupInlineMiddleware(func(namestring,nextfunc(string) slog.Handler) slog.Handler{// [...]returnnext(name)})

mdw:=slogmulti.NewInlineMiddleware(func(ctx context.Context,level slog.Level,nextfunc(context.Context, slog.Level)bool)bool{// [...]returnnext(ctx,level)    },func(ctx context.Context,record slog.Record,nextfunc(context.Context, slog.Record)error)error{// [...]returnnext(ctx,record)    },func(attrs []slog.Attr,nextfunc([]slog.Attr) slog.Handler) slog.Handler{// [...]returnnext(attrs)    },func(namestring,nextfunc(string) slog.Handler) slog.Handler{// [...]returnnext(name)    },)

🤝 Contributing

# Install some dev dependenciesmake tools# Run testsmaketest# ormake watch-test

👤 Contributors

💫 Show your support

📝 License