MoniGo - Runtime Observability for Go Applications

MoniGo is a lightweight, embeddable observability library for Go services. It collects runtime metrics (CPU, memory, goroutines, disk/network I/O), traces function execution with pprof profiling, stores time-series data, and serves a real-time dashboard - all from a single go get.

Features

• Function-Level Tracing - Profile any function with CPU/memory pprof, adaptive sampling, and reflection-based argument capture
• Pluggable Storage - Persistent disk (tstorage) or volatile in-memory backends
• Real-Time Dashboard - Embedded web UI with system metrics, health scoring, goroutine inspection, and downloadable reports
• Prometheus & OpenTelemetry - Built-in /metrics endpoint and OTLP/gRPC export
• Router Integration - Works with net/http, Gin, Echo, Chi, Fiber, Gorilla Mux
• Dashboard Security - Basic Auth, API Key, IP Whitelist, Rate Limiting middleware
• Headless Mode - Run as a background telemetry agent without the dashboard
• Builder API - Type-safe, chainable configuration with validation

Per-function metrics

Call counts and approximate latency percentiles for every traced function, with memory and goroutine deltas. Percentiles are bucket upper bounds, shown as ~4ms meaning "at most 4ms", and read - below 20 calls rather than pretending three samples make a p95.

Goroutine inspection

Live goroutines grouped by stack signature, with state, how long each group has been blocked, and growth across snapshots -- so a leak shows up as a group that keeps growing rather than a number that keeps rising.

Exporter status

Prometheus and OpenTelemetry reported in their own terms. MoniGo is scraped by Prometheus and pushes to OTel, so the pull exporter shows when it was last scraped and carries no failure count -- a failed scrape fails at the collector, and the server never hears about it.

Installation

go get github.com/iyashjayesh/monigo@latest

Requires Go 1.22+.

Quick Start

package main

import (
    "log"
    "math"
    "net/http"

    "github.com/iyashjayesh/monigo"
)

func main() {
    m := monigo.NewBuilder().
        WithServiceName("my-api").
        WithPort(8080).
        WithStorageType("memory").
        WithSamplingRate(100).
        Build()

    go func() {
        if err := m.Start(); err != nil {
            log.Fatalf("monigo: %v", err)
        }
    }()

    http.HandleFunc("/compute", func(w http.ResponseWriter, r *http.Request) {
        monigo.TraceFunction(r.Context(), heavyWork)
        w.Write([]byte("done"))
    })

    log.Fatal(http.ListenAndServe(":9000", nil))
}

func heavyWork() {
    var sum float64
    for i := 0; i < 1e8; i++ {
        sum += math.Sqrt(float64(i))
    }
}

Dashboard: http://localhost:8080 - Your app: http://localhost:9000

Configuration

All configuration is done via the builder pattern:

m := monigo.NewBuilder().
    WithServiceName("order-service").       // Required
    WithPort(8080).                         // Dashboard port (default: 8080)
    WithStorageType("disk").                // "disk" or "memory" (default: "disk")
    WithRetentionPeriod("7d").              // Data retention (default: "7d")
    WithDataPointsSyncFrequency("5m").      // Metric flush interval (default: "5m")
    WithSamplingRate(100).                  // Trace 1 in N calls (default: 100)
    WithMaxCPUUsage(90).                    // Health threshold (default: 95%)
    WithMaxMemoryUsage(90).                 // Health threshold (default: 95%)
    WithMaxGoRoutines(500).                 // Health threshold (default: 100)
    WithAlertWebhook("https://...").        // Health breach webhook (default: off)
    WithStaleGoroutineThreshold(24*time.Hour). // Stale goroutine cutoff (default: 24h)
    WithHeadless(false).                    // true = no dashboard (default: false)
    WithTimeZone("UTC").                    // Timezone (default: "Local")
    WithLogLevel(slog.LevelInfo).           // Log level
    WithOTelEndpoint("localhost:4317").      // OTLP gRPC endpoint
    WithOTelHeaders(map[string]string{      // OTel auth headers
        "Authorization": "Bearer <token>",
    }).
    Build()

Health Breach Alerts

MoniGo computes a system and service health score on every collection cycle. Point WithAlertWebhook at an HTTP endpoint to be notified when either score drops below 70. Left unset, MoniGo makes no outbound requests.

m := monigo.NewBuilder().
    WithServiceName("order-service").
    WithAlertWebhook("https://hooks.slack.com/services/...").
    Build()

Delivery is POST with Content-Type: application/json:

{
  "service_name": "order-service",
  "timestamp": "2026-08-28T11:59:20Z",
  "message": "Service Health Alert: Service usage exceeds allowed limits: CPU Usage 143.20% / 95.00%, ...",
  "health_score": 42.5
}

Alerts are dispatched off the metrics collection path, so a slow or unreachable endpoint never stalls metric collection. Requests time out after 10 seconds, and a minimum of 5 minutes separates deliveries so a flapping service cannot emit an alert on every tick. Delivery failures are logged and otherwise ignored.

Build() rejects a webhook URL that is not http:// or https://.

Goroutine Leak Detection

Every metrics collection cycle captures all goroutine stacks and evaluates them for two independent leak signals. The verdict appears on the Go Routines Stats page and in the go-routines-stats API response, and raises the alert webhook if one is configured.

Stale goroutines. The Go runtime stamps a block duration into each goroutine's stack header once it has been parked for over a minute:

goroutine 21 [chan receive, 47 minutes]:

Any goroutine blocked at or beyond the threshold is reported as stale. The default is 24h; WithStaleGoroutineThreshold takes any duration of 1m or more (below that is not representable, since the runtime reports whole minutes only).

Growing call stacks. Goroutines are grouped by identical call stack, and the per-group counts are retained across the last 5 collection cycles. A group is flagged only if its count rose in every retained cycle. That rule is deliberately strict: a worker pool scaling up briefly, plateauing, or oscillating is not a leak, and a group absent from the oldest snapshot is treated as new rather than growing. Nothing is reported until the window is full, so a freshly started service cannot raise a false alarm from two data points.

m := monigo.NewBuilder().
    WithServiceName("order-service").
    WithStaleGoroutineThreshold(6 * time.Hour).
    WithAlertWebhook("https://hooks.slack.com/services/...").
    Build()

The report is carried on the goroutine stats response:

{
  "number_of_goroutines": 456,
  "leak_report": {
    "total_goroutines": 456,
    "stale_goroutines": 443,
    "growing_groups": 1,
    "leak_suspected": true,
    "snapshots_retained": 5,
    "snapshots_required": 5,
    "stale_threshold_minutes": 360,
    "message": "Possible goroutine leak: 443 goroutine(s) blocked for at least 6h; 1 call stack(s) growing across the last 5 snapshots (total goroutines: 456).",
    "suspicious_groups": [
      {
        "signature": "a3f19c2d4e5b",
        "state": "chan receive",
        "count": 440,
        "blocked_minutes": 421,
        "growth": 100,
        "stale": true,
        "growing": true,
        "call_stack": "main.worker()\n\t/app/main.go:31 +0x24\n..."
      }
    ]
  }
}

Detection is driven by the metrics collection cycle rather than by dashboard polling, so growth snapshots stay evenly spaced and a leak is caught whether or not anyone has a browser tab open.

Function Tracing

// Simple function
monigo.TraceFunction(ctx, myFunc)

// Function with arguments
monigo.TraceFunctionWithArgs(ctx, processOrder, orderID, userID)

// Function with single return
result := monigo.TraceFunctionWithReturn(ctx, calculateTotal, items).(float64)

// Function with multiple returns
results := monigo.TraceFunctionWithReturns(ctx, validateInput, data)
val := results[0].(string)
err := results[1].(error)

Each traced call captures: execution time, memory delta, goroutine delta, and (at sampling rate) CPU/memory pprof profiles.

Dashboard Security

mw, stop := monigo.RateLimitMiddleware(100, time.Minute)
defer stop()

m := monigo.NewBuilder().
    WithServiceName("secure-api").
    WithPort(8080).
    WithDashboardMiddleware(
        monigo.BasicAuthMiddleware("admin", "s3cret"),
        mw,
    ).
    WithAPIMiddleware(
        monigo.APIKeyMiddleware("my-api-key"),
    ).
    Build()

Router Integration

MoniGo integrates with any Go HTTP router:

// Standard net/http
mux := http.NewServeMux()
monigo.RegisterDashboardHandlers(mux)

// Fiber
app.All("/monigo/*", adaptor.HTTPHandler(monigo.GetUnifiedHandler()))

// Gin / Echo / Chi - use GetAPIHandlers() map
for path, handler := range monigo.GetAPIHandlers() {
    router.GET(path, gin.WrapF(handler))
}

See example/router-integration/ for complete examples.

API Endpoints

Method	Path	Description
GET	/monigo/api/v1/metrics	Current service statistics
GET	/monigo/api/v1/service-info	Service metadata
POST	/monigo/api/v1/service-metrics	Query time-series data
GET	/monigo/api/v1/go-routines-stats	Goroutine stack analysis
GET	/monigo/api/v1/function	Function trace summary
GET	/monigo/api/v1/function-details	pprof reports for a function
POST	/monigo/api/v1/reports	Aggregated report data
GET	/metrics	Prometheus scrape endpoint

Architecture

┌─────────────────────────────────────────────────┐
│                  Your Application                │
│                                                  │
│  monigo.TraceFunction(ctx, fn)                   │
│  monigo.Start() / monigo.Initialize()            │
└───────────┬─────────────────────┬────────────────┘
            │                     │
    ┌───────▼───────┐    ┌───────▼────────┐
    │   core/       │    │   monigo.go    │
    │  Metrics      │    │  Dashboard     │
    │  Collection   │    │  HTTP Server   │
    │  Health Score │    │  Middleware     │
    │  Profiling    │    │  Router Integ. │
    └───────┬───────┘    └───────┬────────┘
            │                     │
    ┌───────▼─────────────────────▼────────┐
    │           timeseries/                 │
    │  tstorage (disk) │ InMemoryStorage   │
    └───────┬──────────────────────────────┘
            │
    ┌───────▼───────────────────────────────┐
    │           exporters/                   │
    │  Prometheus Collector │ OTel Exporter  │
    └───────────────────────────────────────┘
            │
    ┌───────▼───────────────────────────────┐
    │           internal/                    │
    │  registry │ pipeline │ exporter │ log  │
    └───────────────────────────────────────┘

Package responsibilities:

Package	Role
monigo (root)	Public API, dashboard server, middleware, builder
core	System metric collection, function tracing, health scoring
common	Utilities, unit conversion, process info
timeseries	Storage abstraction (disk + in-memory)
exporters	Prometheus collector, OTel OTLP exporter
internal/registry	Thread-safe metric registry
internal/pipeline	Async metric export pipeline
internal/exporter	Exporter interface + fan-out
internal/logger	Race-safe structured logger (slog)
models	Shared data structures
api	HTTP handlers for all endpoints

What Works Well

• Zero-dependency embedding - Single go get, no sidecar, no agent
• Goroutine-safe metrics - Atomic sampling, mutex-protected maps, sync.Once singletons
• Adaptive profiling - Sampling prevents pprof overhead in hot paths
• Clean builder API - Validation at build time catches misconfiguration early
• Race-free logger - atomic.Pointer eliminates the common slog data race

Examples

Example	Path
Basic usage	example/main.go
Function tracing	example/function-trace-example/
Gin integration	example/router-integration/gin-integration/
Echo integration	example/router-integration/echo-integration/
Fiber integration	example/router-integration/fiber-integration/
Standard mux	example/router-integration/standard-mux-integration/
Gorilla mux	example/router-integration/gorilla-mux-integration/
Basic auth	example/security-examples/basic-auth/
API key auth	example/security-examples/api-key/
IP whitelist	example/security-examples/ip-whitelist-example/
Custom auth	example/security-examples/custom-auth/

Documentation

Full guides and API reference: iyashjayesh.github.io/monigo-website

Topic	Link
Introduction & Features	Docs
Configuration (Builder API)	Docs
Function Tracing	Docs
Router Integration	Docs
Dashboard Security	Docs
Migration (v1 → v2)	Docs

Contributing

We welcome contributions. Please see CONTRIBUTING.md for guidelines.

If you find MoniGo useful, consider giving it a star.

License

Apache 2.0 - see LICENSE.

Contact

For questions or feedback: open an issue or reach out at iyashjayesh@gmail.com / LinkedIn.

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