wasilak/go-hello-world

package gin

import (
    "context"
    "log/slog"
    "net/http"
    "os"
    "strings"

    "github.com/arl/statsviz"
    "github.com/gin-contrib/gzip"
    "github.com/gin-gonic/gin"
    sloggin "github.com/samber/slog-gin"
    "github.com/wasilak/go-hello-world/utils"
    ginprometheus "github.com/zsais/go-gin-prometheus"
    "go.opentelemetry.io/contrib/instrumentation/github.com/gin-gonic/gin/otelgin"
    "go.opentelemetry.io/otel/trace"
)

var tracer trace.Tracer

type slogWriter struct{}

func (sw slogWriter) Write(p []byte) (n int, err error) {
    slog.Default().Info(string(p))
    return len(p), nil
}

func Init(ctx context.Context, listenAddr, logLevel *string, otelEnabled, statsvizEnabled *bool, tr trace.Tracer, traceProvider *trace.TracerProvider) {
    slog.DebugContext(ctx, "Features supported", "loggergo", true, "statsviz", true, "tracing", true)
    tracer = tr

    gin.DefaultWriter = slogWriter{}

    // Create a Gin router
    r := gin.Default()

    // Prometheus Middleware
    p := ginprometheus.NewPrometheus(strings.ReplaceAll(utils.GetAppName(), "-", "_"))
    p.Use(r)

    // OpenTelemetry Middleware
    if *otelEnabled {
        r.Use(otelgin.Middleware(utils.GetAppName(), otelgin.WithTracerProvider(*traceProvider)))
    }

    // Gzip Middleware
    r.Use(gzip.Gzip(gzip.DefaultCompression))

    // Custom Logging Middleware
    r.Use(sloggin.New(slog.Default()))
    r.Use(gin.Recovery())

    // Debug Mode
    if strings.EqualFold(*logLevel, "debug") {
        gin.SetMode(gin.DebugMode)
        slog.DebugContext(ctx, "Debug mode enabled")
    }

    // Define Routes
    r.GET("/", mainRoute)
    r.GET("/health", healthRoute)
    // r.GET("/metrics", gin.WrapH(promhttp.Handler()))

    // Optional Statviz
    if *statsvizEnabled {
        // Create statsviz server.
        srv, _ := statsviz.NewServer()

        // Specific route for WebSocket
        r.GET("/debug/statsviz/ws", gin.WrapF(srv.Ws()))

        // Static route for the index
        r.GET("/debug/statsviz", func(c *gin.Context) {
            c.Redirect(http.StatusMovedPermanently, "/debug/statsviz/")
        })

        // Define more specific routes for statsviz
        r.GET("/debug/statsviz/plots", gin.WrapH(srv.Index()))
        r.GET("/debug/statsviz/metrics", gin.WrapH(srv.Index()))
        // Add other specific paths as needed
    }

    // Start Server
    slog.DebugContext(ctx, "Starting server", "address", *listenAddr)
    if err := r.Run(*listenAddr); err != nil {
        slog.ErrorContext(ctx, "Server exited with error", "error", err)
        os.Exit(1)
    }
}