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mirror of https://github.com/taigrr/log-socket synced 2026-03-20 14:52:27 -07:00

3 Commits

Author SHA1 Message Date
cac3d127ee chore: update to Go 1.26, resolve slog LogValuer values 2026-03-02 03:48:00 +00:00
90471833d0 feat(slog): add slog.Handler adapter for log-socket
Implements log/slog.Handler that routes structured log records into the
log-socket broadcasting system. Supports namespaces, WithAttrs,
WithGroup, and configurable minimum level.

Also adds Broadcast() as a public entry point for adapter packages
that construct log.Entry values directly.
2026-03-02 03:44:15 +00:00
703f80c5f6 docs: add example programs for common usage patterns
Adds four focused examples in examples/ directory:
- basic: drop-in logger with web UI
- namespaces: namespace-based logging by component
- client: programmatic log client with filtering
- log-levels: all log levels and filtering

Fixes #7
2026-02-20 08:02:17 +00:00
8 changed files with 540 additions and 3 deletions

36
examples/basic/main.go Normal file
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@@ -0,0 +1,36 @@
// Example: basic usage of log-socket as a drop-in logger.
//
// This demonstrates using the package-level logging functions,
// which work similarly to the standard library's log package.
package main
import (
"fmt"
"net/http"
"github.com/taigrr/log-socket/v2/browser"
logger "github.com/taigrr/log-socket/v2/log"
"github.com/taigrr/log-socket/v2/ws"
)
func main() {
defer logger.Flush()
// Set the minimum log level (default is LTrace, showing everything)
logger.SetLogLevel(logger.LDebug)
// Package-level functions log to the "default" namespace
logger.Info("Application starting up")
logger.Debug("Debug mode enabled")
logger.Warnf("Config file not found at %s, using defaults", "/etc/app/config.yaml")
logger.Errorf("Failed to connect to database: %s", "connection refused")
// Print/Printf/Println are aliases for Info
logger.Println("This is equivalent to Infoln")
// Start the web UI so you can view logs at http://localhost:8080
http.HandleFunc("/ws", ws.LogSocketHandler)
http.HandleFunc("/", browser.LogSocketViewHandler)
fmt.Println("Log viewer available at http://localhost:8080")
logger.Fatal(http.ListenAndServe("0.0.0.0:8080", nil))
}

63
examples/client/main.go Normal file
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@@ -0,0 +1,63 @@
// Example: programmatic log client with namespace filtering.
//
// This shows how to create a Client that receives log entries
// programmatically, optionally filtered to specific namespaces.
// Useful for building custom log processors, alerting, or forwarding.
package main
import (
"fmt"
"time"
logger "github.com/taigrr/log-socket/v2/log"
)
func main() {
defer logger.Flush()
// Create a client that receives ALL log entries
allLogs := logger.CreateClient()
allLogs.SetLogLevel(logger.LInfo)
// Create a client that only receives "database" and "auth" logs
securityLogs := logger.CreateClient("database", "auth")
securityLogs.SetLogLevel(logger.LWarn) // Only warnings and above
dbLog := logger.NewLogger("database")
authLog := logger.NewLogger("auth")
apiLog := logger.NewLogger("api")
// Process all logs
go func() {
for {
entry := allLogs.Get()
fmt.Printf("[ALL] %s [%s] %s: %s\n",
entry.Timestamp.Format(time.TimeOnly),
entry.Namespace, entry.Level, entry.Output)
}
}()
// Process only security-relevant warnings/errors
go func() {
for {
entry := securityLogs.Get()
if entry.Level == "ERROR" || entry.Level == "WARN" {
fmt.Printf("🚨 SECURITY ALERT [%s] %s: %s\n",
entry.Namespace, entry.Level, entry.Output)
}
}
}()
// Generate some logs
for i := 0; i < 5; i++ {
apiLog.Info("API request processed")
dbLog.Info("Query executed successfully")
dbLog.Warn("Connection pool running low")
authLog.Error("Brute force attempt detected")
time.Sleep(1 * time.Second)
}
// Clean up clients when done
allLogs.Destroy()
securityLogs.Destroy()
}

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@@ -0,0 +1,48 @@
// Example: log level filtering and all available levels.
//
// log-socket supports 8 log levels from TRACE (most verbose)
// to FATAL (least verbose). Setting a log level filters out
// everything below it.
package main
import (
"fmt"
logger "github.com/taigrr/log-socket/v2/log"
)
func main() {
defer logger.Flush()
fmt.Println("=== All log levels (TRACE and above) ===")
logger.SetLogLevel(logger.LTrace)
logger.Trace("Detailed execution trace — variable x = 42")
logger.Debug("Processing request for user_id=123")
logger.Info("Server started on :8080")
logger.Notice("Configuration reloaded")
logger.Warn("Disk usage at 85%")
logger.Error("Failed to send email: SMTP timeout")
// logger.Panic("...") — would panic
// logger.Fatal("...") — would os.Exit(1)
fmt.Println("\n=== Formatted variants ===")
logger.Infof("Request took %dms", 42)
logger.Warnf("Retrying in %d seconds (attempt %d/%d)", 5, 2, 3)
logger.Errorf("HTTP %d: %s", 503, "Service Unavailable")
fmt.Println("\n=== Only WARN and above ===")
logger.SetLogLevel(logger.LWarn)
logger.Debug("This will NOT appear")
logger.Info("This will NOT appear either")
logger.Warn("This WILL appear")
logger.Error("This WILL appear too")
fmt.Println("\n=== Per-logger levels via namespaced loggers ===")
logger.SetLogLevel(logger.LTrace) // Reset global
appLog := logger.NewLogger("app")
appLog.Info("Namespaced loggers inherit the global output but tag entries")
appLog.Warnf("Something needs attention in the %s subsystem", "app")
}

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@@ -0,0 +1,73 @@
// Example: namespace-based logging for organizing logs by component.
//
// Namespaces let you tag log entries by subsystem (api, database, auth, etc.)
// and filter them in the web UI or via programmatic clients.
package main
import (
"fmt"
"math/rand"
"net/http"
"time"
"github.com/taigrr/log-socket/v2/browser"
logger "github.com/taigrr/log-socket/v2/log"
"github.com/taigrr/log-socket/v2/ws"
)
func main() {
defer logger.Flush()
// Create loggers for different subsystems
apiLog := logger.NewLogger("api")
dbLog := logger.NewLogger("database")
authLog := logger.NewLogger("auth")
cacheLog := logger.NewLogger("cache")
// Simulate application activity
go func() {
for {
apiLog.Infof("GET /api/users — 200 OK (%dms)", rand.Intn(200))
apiLog.Debugf("Request headers: Accept=application/json")
time.Sleep(1 * time.Second)
}
}()
go func() {
for {
dbLog.Infof("SELECT * FROM users — %d rows", rand.Intn(100))
if rand.Float64() < 0.3 {
dbLog.Warn("Slow query detected (>500ms)")
}
time.Sleep(2 * time.Second)
}
}()
go func() {
for {
if rand.Float64() < 0.7 {
authLog.Info("User login successful")
} else {
authLog.Error("Failed login attempt from 192.168.1.42")
}
time.Sleep(3 * time.Second)
}
}()
go func() {
for {
cacheLog.Tracef("Cache hit ratio: %.1f%%", rand.Float64()*100)
if rand.Float64() < 0.1 {
cacheLog.Warn("Cache eviction triggered")
}
time.Sleep(5 * time.Second)
}
}()
// The /api/namespaces endpoint lists all active namespaces
http.HandleFunc("/ws", ws.LogSocketHandler)
http.HandleFunc("/api/namespaces", ws.NamespacesHandler)
http.HandleFunc("/", browser.LogSocketViewHandler)
fmt.Println("Log viewer with namespace filtering at http://localhost:8080")
logger.Fatal(http.ListenAndServe("0.0.0.0:8080", nil))
}

2
go.mod
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@@ -1,5 +1,5 @@
module github.com/taigrr/log-socket/v2
go 1.25.6
go 1.26.0
require github.com/gorilla/websocket v1.5.3

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@@ -103,7 +103,7 @@ func createLog(e Entry) {
namespacesMux.Lock()
namespaces[e.Namespace] = true
namespacesMux.Unlock()
sliceTex.Lock()
for _, c := range clients {
func(c *Client, e Entry) {
@@ -133,7 +133,7 @@ func createLog(e Entry) {
func GetNamespaces() []string {
namespacesMux.RLock()
defer namespacesMux.RUnlock()
result := make([]string, 0, len(namespaces))
for ns := range namespaces {
result = append(result, ns)
@@ -556,3 +556,37 @@ func fileInfo(skip int) string {
}
return fmt.Sprintf("%s:%d", file, line)
}
// Broadcast sends an [Entry] to all registered clients. This is the public
// entry point used by adapter packages (such as the slog handler) that
// construct entries themselves. The unexported level field is inferred from
// [Entry.Level] when not already set.
func Broadcast(e Entry) {
if e.level == 0 && e.Level != "" && e.Level != "TRACE" {
e.level = parseLevelString(e.Level)
}
createLog(e)
}
func parseLevelString(s string) Level {
switch s {
case "TRACE":
return LTrace
case "DEBUG":
return LDebug
case "INFO":
return LInfo
case "NOTICE":
return LNotice
case "WARN":
return LWarn
case "ERROR":
return LError
case "PANIC":
return LPanic
case "FATAL":
return LFatal
default:
return LInfo
}
}

165
slog/handler.go Normal file
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@@ -0,0 +1,165 @@
// Package slog provides a [log/slog.Handler] that routes structured log
// records into the log-socket broadcasting system, giving every slog-based
// caller free WebSocket streaming and the browser viewer UI.
package slog
import (
"context"
"fmt"
"log/slog"
"runtime"
"strings"
"github.com/taigrr/log-socket/v2/log"
)
// Handler implements [slog.Handler] by converting each [slog.Record] into a
// log-socket [log.Entry] and feeding it through the normal broadcast path.
//
// Attributes accumulated via [Handler.WithAttrs] are prepended to the log
// message as key=value pairs. Groups set via [Handler.WithGroup] prefix
// attribute keys with "group.".
type Handler struct {
namespace string
level slog.Level
attrs []slog.Attr
groups []string
}
// ensure interface compliance at compile time.
var _ slog.Handler = (*Handler)(nil)
// Option configures a [Handler].
type Option func(*Handler)
// WithNamespace sets the log-socket namespace for entries produced by this
// handler. If empty, [log.DefaultNamespace] is used.
func WithNamespace(ns string) Option {
return func(h *Handler) {
h.namespace = ns
}
}
// WithLevel sets the minimum slog level the handler will accept.
func WithLevel(l slog.Level) Option {
return func(h *Handler) {
h.level = l
}
}
// NewHandler returns a new [Handler] that writes to the log-socket broadcast
// system. Options may be used to set the namespace and minimum level.
func NewHandler(opts ...Option) *Handler {
h := &Handler{
namespace: log.DefaultNamespace,
level: slog.LevelDebug,
}
for _, o := range opts {
o(h)
}
return h
}
// Enabled reports whether the handler is configured to process records at
// the given level.
func (h *Handler) Enabled(_ context.Context, level slog.Level) bool {
return level >= h.level
}
// Handle converts r into a log-socket Entry and broadcasts it.
func (h *Handler) Handle(_ context.Context, r slog.Record) error {
var b strings.Builder
b.WriteString(r.Message)
// Append pre-collected attrs.
for _, a := range h.attrs {
writeAttr(&b, h.groups, a)
}
// Append record-level attrs.
r.Attrs(func(a slog.Attr) bool {
writeAttr(&b, h.groups, a)
return true
})
file := "???"
if r.PC != 0 {
fs := runtime.CallersFrames([]uintptr{r.PC})
f, _ := fs.Next()
if f.File != "" {
short := f.File
if idx := strings.LastIndex(short, "/"); idx >= 0 {
short = short[idx+1:]
}
file = fmt.Sprintf("%s:%d", short, f.Line)
}
}
e := log.Entry{
Timestamp: r.Time,
Output: b.String(),
File: file,
Level: slogLevelToString(r.Level),
Namespace: h.namespace,
}
log.Broadcast(e)
return nil
}
// WithAttrs returns a new Handler with the given attributes appended.
func (h *Handler) WithAttrs(attrs []slog.Attr) slog.Handler {
h2 := h.clone()
h2.attrs = append(h2.attrs, attrs...)
return h2
}
// WithGroup returns a new Handler where subsequent attributes are nested
// under the given group name.
func (h *Handler) WithGroup(name string) slog.Handler {
if name == "" {
return h
}
h2 := h.clone()
h2.groups = append(h2.groups, name)
return h2
}
func (h *Handler) clone() *Handler {
h2 := &Handler{
namespace: h.namespace,
level: h.level,
attrs: make([]slog.Attr, len(h.attrs)),
groups: make([]string, len(h.groups)),
}
copy(h2.attrs, h.attrs)
copy(h2.groups, h.groups)
return h2
}
func writeAttr(b *strings.Builder, groups []string, a slog.Attr) {
a.Value = a.Value.Resolve()
if a.Equal(slog.Attr{}) {
return
}
b.WriteByte(' ')
for _, g := range groups {
b.WriteString(g)
b.WriteByte('.')
}
b.WriteString(a.Key)
b.WriteByte('=')
b.WriteString(a.Value.String())
}
func slogLevelToString(l slog.Level) string {
switch {
case l >= slog.LevelError:
return "ERROR"
case l >= slog.LevelWarn:
return "WARN"
case l >= slog.LevelInfo:
return "INFO"
default:
return "DEBUG"
}
}

118
slog/handler_test.go Normal file
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@@ -0,0 +1,118 @@
package slog
import (
"context"
"log/slog"
"testing"
"time"
"github.com/taigrr/log-socket/v2/log"
)
// getWithTimeout reads from a log client with a timeout to avoid hanging tests.
func getWithTimeout(c *log.Client, timeout time.Duration) (log.Entry, bool) {
ch := make(chan log.Entry, 1)
go func() { ch <- c.Get() }()
select {
case e := <-ch:
return e, true
case <-time.After(timeout):
return log.Entry{}, false
}
}
func TestHandler_Enabled(t *testing.T) {
h := NewHandler(WithLevel(slog.LevelWarn))
if h.Enabled(context.Background(), slog.LevelInfo) {
t.Error("expected Info to be disabled when min level is Warn")
}
if !h.Enabled(context.Background(), slog.LevelWarn) {
t.Error("expected Warn to be enabled")
}
if !h.Enabled(context.Background(), slog.LevelError) {
t.Error("expected Error to be enabled")
}
}
func TestHandler_Handle(t *testing.T) {
c := log.CreateClient()
defer c.Destroy()
c.SetLogLevel(log.LTrace)
h := NewHandler(WithNamespace("test-ns"))
logger := slog.New(h)
logger.Info("hello world", "key", "value")
e, ok := getWithTimeout(c, time.Second)
if !ok {
t.Fatal("timed out waiting for log entry")
}
if e.Namespace != "test-ns" {
t.Errorf("namespace = %q, want %q", e.Namespace, "test-ns")
}
if e.Level != "INFO" {
t.Errorf("level = %q, want INFO", e.Level)
}
if e.Output == "" {
t.Error("output should not be empty")
}
}
func TestHandler_WithAttrs(t *testing.T) {
c := log.CreateClient()
defer c.Destroy()
c.SetLogLevel(log.LTrace)
h := NewHandler()
h2 := h.WithAttrs([]slog.Attr{slog.String("service", "api")})
logger := slog.New(h2)
logger.Info("request")
e, ok := getWithTimeout(c, time.Second)
if !ok {
t.Fatal("timed out")
}
if e.Output != "request service=api" {
t.Errorf("output = %q, want %q", e.Output, "request service=api")
}
}
func TestHandler_WithGroup(t *testing.T) {
c := log.CreateClient()
defer c.Destroy()
c.SetLogLevel(log.LTrace)
h := NewHandler()
h2 := h.WithGroup("http").WithAttrs([]slog.Attr{slog.Int("status", 200)})
logger := slog.New(h2)
logger.Info("done")
e, ok := getWithTimeout(c, time.Second)
if !ok {
t.Fatal("timed out")
}
if e.Output != "done http.status=200" {
t.Errorf("output = %q, want %q", e.Output, "done http.status=200")
}
}
func TestSlogLevelMapping(t *testing.T) {
tests := []struct {
level slog.Level
want string
}{
{slog.LevelDebug, "DEBUG"},
{slog.LevelInfo, "INFO"},
{slog.LevelWarn, "WARN"},
{slog.LevelError, "ERROR"},
}
for _, tt := range tests {
got := slogLevelToString(tt.level)
if got != tt.want {
t.Errorf("slogLevelToString(%v) = %q, want %q", tt.level, got, tt.want)
}
}
}