feat!: decouple public logger from lib-observability (fixes #24)

CHANGELOG.md

@@ -149,6 +149,18 @@ Improvements:
   but no endpoint (external or internal) is configured.
 
 ### Changed
+- **BREAKING — public logger decoupled from lib-observability (#24)**:
+  `Config.Logger` and `WithLogger()` now take the new stdlib-only
+  `libsd.Logger` interface (`InfoContext`/`WarnContext`/`ErrorContext`/
+  `DebugContext(ctx, msg, ...any)`) instead of lib-observability's
+  `log.Logger`. Any `slog`-compatible logger — including the stdlib
+  `*slog.Logger` (e.g. `slog.Default()`) — satisfies it directly.
+  **Migration**: replace the `log.Logger` you pass to `WithLogger()` /
+  `Config.Logger` with a `*slog.Logger`. Consumers no longer need
+  lib-observability as a direct dependency, and no adapter wrapper is
+  required on the caller side. (lib-observability remains an internal
+  implementation detail of this lib via a private adapter and is not part
+  of the public API.)
 - **BREAKING — `Service.EndpointFor` signature**: now returns `(Endpoint, error)`
   instead of a single `Endpoint`. Callers must handle the error
   (`ErrEndpointViewUnavailable`).

README.md

@@ -67,13 +67,22 @@ stopped by `Manager.Close()`.
 - `Manager` — entry point; created with `New(cfg, opts...)`.
 - `Registry` — interface for the Consul backend; can be replaced by an in-memory stub in tests.
 - `Service` / `HealthCheck` / `Event` — domain types.
+- `Logger` — minimal, version-agnostic, `slog`-compatible logging interface. Pass any
+  `*slog.Logger` (or equivalent) directly; no `lib-observability` dependency required.
 
 **Functional options:**
 
 ```go
-libsd.WithLogger(logger)   // inject a lib-commons log.Logger
+libsd.WithLogger(logger)   // inject any slog-compatible libsd.Logger (e.g. *slog.Logger)
 ```
 
+> **Breaking change (logger decoupling):** `Config.Logger` and `WithLogger()` now take
+> the stdlib-only `libsd.Logger` interface (`InfoContext`/`WarnContext`/`ErrorContext`/`DebugContext`)
+> instead of `lib-observability`'s `log.Logger`. Pass a `*slog.Logger` directly. A
+> `lib-observability` `log.Logger` no longer satisfies the API (it uses `Log(ctx, level, msg, ...Field)`),
+> so callers relying on it must switch to an `slog`-compatible logger. This removes the
+> version-pinning coupling on `lib-observability`.
+
 ## Usage
 
 ```go

close_test.go

@@ -210,7 +210,7 @@ func TestManagerClose_RegistryWithoutCloser(t *testing.T) {
 func TestManagerClose_DisabledManagerSafe(t *testing.T) {
 	t.Parallel()
 
-	m, err := New(Config{Enabled: false, Logger: log.NewNop()})
+	m, err := New(Config{Enabled: false, Logger: nopLogger()})
 	require.NoError(t, err)
 
 	assert.NotPanics(t, func() {

config.go

@@ -7,8 +7,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-
-	"github.com/LerianStudio/lib-observability/log"
 )
 
 const (
@@ -171,8 +169,9 @@ type Config struct {
 	AllowStale *bool
 
 	// Logger receives structured log output from the Manager and registry.
-	// Defaults to log.NewNop() when nil.
-	Logger log.Logger
+	// It is a version-agnostic, slog-compatible interface (see libsd.Logger):
+	// pass any *slog.Logger or equivalent directly. A nil Logger silences output.
+	Logger Logger
 }
 
 // ConfigFromEnv returns a Config populated from environment variables.
@@ -250,10 +249,6 @@ func (c Config) Validate() error {
 }
 
 func (c Config) withDefaults() Config {
-	if c.Logger == nil {
-		c.Logger = log.NewNop()
-	}
-
 	if c.ConsulAddr == "" {
 		c.ConsulAddr = "localhost:8500"
 	}

consul_dual_integration_test.go

@@ -10,7 +10,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/LerianStudio/lib-observability/log"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -42,7 +41,7 @@ func integrationManagerDual(t *testing.T, internalPort int, preferView EndpointV
 		AdvertiseInternalAddr: advertiseAddr, // internal view — real/reachable (host.docker.internal)
 		AdvertiseInternalPort: internalPort,
 		PreferView:            preferView,
-		Logger:                log.NewNop(),
+		Logger:                nopLogger(),
 	})
 	require.NoError(t, err)
 
@@ -271,7 +270,7 @@ func integrationManagerInternalOnly(t *testing.T, internalPort int) *Manager {
 		AdvertiseInternalAddr: advertiseAddr, // internal view — real/reachable
 		AdvertiseInternalPort: internalPort,
 		// AdvertiseAddr intentionally empty: no external endpoint is advertised.
-		Logger: log.NewNop(),
+		Logger: nopLogger(),
 	})
 	require.NoError(t, err)
 

consul_integration_test.go

@@ -11,7 +11,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/LerianStudio/lib-observability/log"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -30,7 +29,7 @@ func integrationManager(t *testing.T) *Manager {
 		Enabled:       true,
 		ConsulAddr:    consulAddr,
 		AdvertiseAddr: advertiseAddr,
-		Logger:        log.NewNop(),
+		Logger:        nopLogger(),
 	})
 	require.NoError(t, err)
 
@@ -269,7 +268,7 @@ func TestIntegration_ResolveHonorsDialTimeout(t *testing.T) {
 		ConsulAddr:    "10.255.255.1:8500", // blackhole: SYNs are dropped, dial hangs until deadline
 		AdvertiseAddr: advertiseAddr,
 		DialTimeout:   dialTimeout,
-		Logger:        log.NewNop(),
+		Logger:        nopLogger(),
 	})
 	require.NoError(t, err)
 	t.Cleanup(func() { _ = m.Close() })

logger.go

@@ -0,0 +1,107 @@
+package libsd
+
+import (
+	"context"
+	"strings"
+
+	"github.com/LerianStudio/lib-observability/log"
+)
+
+// Logger is the minimal, version-agnostic structured-logging contract that
+// lib-service-discovery accepts from consumers. It uses only stdlib types and
+// mirrors the context-aware methods of *slog.Logger, so any slog-compatible
+// logger (including the stdlib *slog.Logger) satisfies it directly — with no
+// dependency on lib-observability and no adapter wrapper on the caller side.
+//
+// The variadic args follow slog semantics: alternating key/value pairs
+// (e.g. "consul", addr) or slog.Attr values.
+type Logger interface {
+	InfoContext(ctx context.Context, msg string, args ...any)
+	WarnContext(ctx context.Context, msg string, args ...any)
+	ErrorContext(ctx context.Context, msg string, args ...any)
+	DebugContext(ctx context.Context, msg string, args ...any)
+}
+
+// obsLoggerAdapter bridges a consumer-supplied libsd.Logger to the
+// lib-observability log.Logger contract used internally by the registry and
+// resolvers, so no internal call site changes. lib-observability remains a
+// private implementation detail and never appears in the public API.
+type obsLoggerAdapter struct {
+	l      Logger
+	attrs  []any
+	groups []string
+}
+
+// toObsLogger wraps a public libsd.Logger as an internal log.Logger. A nil
+// logger yields the lib-observability no-op logger, preserving the prior
+// "nil logger is silent" behaviour.
+func toObsLogger(l Logger) log.Logger {
+	if l == nil {
+		return log.NewNop()
+	}
+
+	return &obsLoggerAdapter{l: l}
+}
+
+// fieldsToArgs converts lib-observability Fields into slog-style key/value
+// args, qualifying keys with the active group prefix.
+func fieldsToArgs(prefix string, fields []log.Field) []any {
+	out := make([]any, 0, len(fields)*2)
+
+	for _, f := range fields {
+		key := f.Key
+		if prefix != "" {
+			key = prefix + "." + f.Key
+		}
+
+		out = append(out, key, f.Value)
+	}
+
+	return out
+}
+
+func (a *obsLoggerAdapter) Log(ctx context.Context, level log.Level, msg string, fields ...log.Field) {
+	prefix := strings.Join(a.groups, ".")
+	args := append(append([]any{}, a.attrs...), fieldsToArgs(prefix, fields)...)
+
+	switch level {
+	case log.LevelError:
+		a.l.ErrorContext(ctx, msg, args...)
+	case log.LevelWarn:
+		a.l.WarnContext(ctx, msg, args...)
+	case log.LevelDebug:
+		a.l.DebugContext(ctx, msg, args...)
+	default: // LevelInfo and any unknown level default to info.
+		a.l.InfoContext(ctx, msg, args...)
+	}
+}
+
+func (a *obsLoggerAdapter) With(fields ...log.Field) log.Logger {
+	prefix := strings.Join(a.groups, ".")
+
+	return &obsLoggerAdapter{
+		l:      a.l,
+		attrs:  append(append([]any{}, a.attrs...), fieldsToArgs(prefix, fields)...),
+		groups: a.groups,
+	}
+}
+
+func (a *obsLoggerAdapter) WithGroup(name string) log.Logger {
+	if name == "" {
+		return a
+	}
+
+	return &obsLoggerAdapter{
+		l:      a.l,
+		attrs:  append([]any{}, a.attrs...),
+		groups: append(append([]string{}, a.groups...), name),
+	}
+}
+
+// Enabled always reports true: level filtering is delegated to the underlying
+// slog-compatible logger supplied by the consumer.
+func (a *obsLoggerAdapter) Enabled(_ log.Level) bool { return true }
+
+// Sync is a no-op: the underlying slog-compatible logger manages its own
+// flushing, and the libsd.Logger contract does not expose a sync hook.
+func (a *obsLoggerAdapter) Sync(_ context.Context) error { return nil }

logger_test.go

@@ -0,0 +1,96 @@
+//go:build unit
+
+package libsd
+
+import (
+	"context"
+	"testing"
+
+	"github.com/LerianStudio/lib-observability/log"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// recordingLogger is a libsd.Logger that captures the level, message and args
+// of each call, so the adapter's level mapping and field translation can be
+// asserted.
+type recordingLogger struct {
+	level string
+	msg   string
+	args  []any
+}
+
+func (r *recordingLogger) InfoContext(_ context.Context, msg string, args ...any) {
+	r.level, r.msg, r.args = "info", msg, args
+}
+
+func (r *recordingLogger) WarnContext(_ context.Context, msg string, args ...any) {
+	r.level, r.msg, r.args = "warn", msg, args
+}
+
+func (r *recordingLogger) ErrorContext(_ context.Context, msg string, args ...any) {
+	r.level, r.msg, r.args = "error", msg, args
+}
+
+func (r *recordingLogger) DebugContext(_ context.Context, msg string, args ...any) {
+	r.level, r.msg, r.args = "debug", msg, args
+}
+
+func TestToObsLogger_NilYieldsNop(t *testing.T) {
+	t.Parallel()
+
+	// A nil public logger must produce a usable, silent internal logger.
+	got := toObsLogger(nil)
+	require.NotNil(t, got)
+	assert.NotPanics(t, func() {
+		got.Log(context.Background(), log.LevelInfo, "silent")
+	})
+}
+
+func TestObsLoggerAdapter_LevelMapping(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		level log.Level
+		want  string
+	}{
+		{log.LevelError, "error"},
+		{log.LevelWarn, "warn"},
+		{log.LevelInfo, "info"},
+		{log.LevelDebug, "debug"},
+		{log.LevelUnknown, "info"}, // unknown levels default to info
+	}
+
+	for _, tc := range cases {
+		rec := &recordingLogger{}
+		toObsLogger(rec).Log(context.Background(), tc.level, "msg")
+		assert.Equal(t, tc.want, rec.level, "level %v", tc.level)
+	}
+}
+
+func TestObsLoggerAdapter_FieldsBecomeSlogArgs(t *testing.T) {
+	t.Parallel()
+
+	rec := &recordingLogger{}
+	toObsLogger(rec).Log(context.Background(), log.LevelInfo, "resolved",
+		log.String("service", "svc-a"), log.Int("count", 3))
+
+	assert.Equal(t, "resolved", rec.msg)
+	assert.Equal(t, []any{"service", "svc-a", "count", 3}, rec.args)
+}
+
+func TestObsLoggerAdapter_WithAndWithGroup(t *testing.T) {
+	t.Parallel()
+
+	rec := &recordingLogger{}
+
+	l := toObsLogger(rec).
+		With(log.String("base", "b")).
+		WithGroup("grp")
+	l.Log(context.Background(), log.LevelWarn, "m", log.String("k", "v"))
+
+	// Accumulated With attrs come first; grouped keys are dotted.
+	assert.Equal(t, []any{"base", "b", "grp.k", "v"}, rec.args)
+	assert.True(t, l.Enabled(log.LevelDebug))
+	assert.NoError(t, l.Sync(context.Background()))
+}

logger_testhelpers_test.go

@@ -0,0 +1,9 @@
+//go:build unit || integration
+
+package libsd
+
+import "log/slog"
+
+// nopLogger returns a silent, slog-compatible libsd.Logger for tests that do
+// not assert on emitted messages. Shared by the unit and integration suites.
+func nopLogger() Logger { return slog.New(slog.DiscardHandler) }

managed_resolver_test.go

@@ -12,7 +12,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/LerianStudio/lib-observability/log"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -160,7 +159,7 @@ func TestManagedResolver_CloseDuringInFlightSeedDoesNotLeak(t *testing.T) {
 		Enabled:       true,
 		ConsulAddr:    "localhost:8500",
 		AdvertiseAddr: "127.0.0.1",
-		Logger:        log.NewNop(),
+		Logger:        nopLogger(),
 	}, WithRegistry(reg))
 	require.NoError(t, err)
 
@@ -239,7 +238,7 @@ func TestManagedResolver_ResolveAfterCloseDoesNotLeakWatcher(t *testing.T) {
 		Enabled:       true,
 		ConsulAddr:    "localhost:8500",
 		AdvertiseAddr: "127.0.0.1",
-		Logger:        log.NewNop(),
+		Logger:        nopLogger(),
 	}, WithRegistry(reg))
 	require.NoError(t, err)
 
@@ -558,7 +557,7 @@ func TestManagedResolver_CloseStopsWatchers(t *testing.T) {
 		Enabled:       true,
 		ConsulAddr:    "localhost:8500",
 		AdvertiseAddr: "127.0.0.1",
-		Logger:        log.NewNop(),
+		Logger:        nopLogger(),
 	}, WithRegistry(reg))
 	require.NoError(t, err)