Initial commit

Author: mxmauro

.gitattributes

@@ -0,0 +1,37 @@
+# Handle line endings automatically for files detected as text
+# and leave all files detected as binary untouched.
+* text=auto
+
+# Force the following filetypes to have unix eols, so Windows does not break them
+*.* text eol=lf
+
+# Windows forced line-endings
+/.idea/* text eol=crlf
+
+#
+## These files are binary and should be left untouched
+#
+
+# (binary is a macro for -text -diff)
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.ico binary
+*.mov binary
+*.mp4 binary
+*.mp3 binary
+*.flv binary
+*.fla binary
+*.swf binary
+*.gz binary
+*.zip binary
+*.7z binary
+*.ttf binary
+*.eot binary
+*.woff binary
+*.pyc binary
+*.pdf binary
+*.ez binary
+*.bz2 binary
+*.swp binary

.gitignore

@@ -0,0 +1,27 @@
+*.~*
+
+*.log
+*.swp
+.idea
+.vscode
+*.patch
+### Go template
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+.DS_Store
+app
+demo
+
+vendor/*
+
+/**/*_test.json

LICENSE

@@ -0,0 +1,8 @@
+Copyright (C) RandLabs.IO - All Rights Reserved.
+Unauthorized copying of this file, via any medium is strictly prohibited.
+Proprietary and confidential.
+
+Only explicitly authorized companies or individual can copy, modify, 
+publish, use, compile, sell, or distribute this software, 
+either in source code form or as a compiled binary, for any purpose, 
+commercial or non-commercial, and by any means.

README.md

@@ -1,2 +1,65 @@
 # go-metrics
+
 Health and Metrics web server library for Go
+
+## Usage with example
+
+```golang
+package example
+
+import (
+	"math/rand"
+
+	metrics "github.com/randlabs/go-metrics"
+)
+
+func main() {
+	// Create a new health & metrics web server
+	srvOpts := metrics.Options{
+		Address:        "127.0.0.1",
+		Port:           3000,
+		HealthCallback: healthCallback, // Setup our health check callback
+	}
+	mws, err := metrics.CreateMetricsWebServer(srvOpts)
+	if err != nil {
+		// handle error
+	}
+
+	// Create a custom prometheus counter
+	err = mws.CreateCounterWithCallback(
+		"random_counter", "A random counter",
+		func() float64 {
+			// Return the counter value.
+			// The common scenario is to have a shared set of variables you regularly update with the current
+			// state of your application.
+			return rand.Float64()
+		},
+	)
+
+	// Start health & metrics web server
+	err = mws.Start()
+	if err != nil {
+		// handle error
+	}
+
+	// your app code may go here
+
+	// Stop health & metrics web server before quitting
+	mws.Stop()
+}
+
+// Health output is in JSON format. Don't forget to add json tags.
+type exampleHealthOutput struct {
+	Status  string `json:"status"`
+}
+
+// Our health callback routine.
+func healthCallback() interface{} {
+	return exampleHealthOutput{
+		Status: "ok",
+	}
+}
+```
+
+## Lincese
+See `LICENSE` file for details.

go.mod

@@ -0,0 +1,26 @@
+module github.com/randlabs/go-metrics
+
+go 1.17
+
+require (
+	github.com/prometheus/client_golang v1.12.1
+	github.com/prometheus/client_model v0.2.0
+	github.com/randlabs/go-webserver v1.0.0
+	github.com/valyala/fasthttp v1.34.0
+	google.golang.org/protobuf v1.27.1
+)
+
+require (
+	github.com/andybalholm/brotli v1.0.4 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/buaazp/fasthttprouter v0.1.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/klauspost/compress v1.15.1 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/prometheus/common v0.32.1 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
+	github.com/valyala/bytebufferpool v1.0.0 // indirect
+	github.com/valyala/tcplisten v1.0.0 // indirect
+	golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5 // indirect
+)

go.sum

@@ -0,0 +1,31 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	webserver "github.com/randlabs/go-webserver"
+	"github.com/valyala/fasthttp"
+)
+
+// -----------------------------------------------------------------------------
+
+func (mws *MetricsWebServer) getHealthHandler() fasthttp.RequestHandler {
+	return func (ctx *webserver.RequestCtx) {
+		webserver.EnableCORS(ctx)
+		webserver.DisableCache(ctx)
+
+		// Get current state from callback
+		state := mws.healthCallback()
+
+		// Encode and send output
+		webserver.SendJSON(ctx, state)
+	}
+}
+
+func (mws *MetricsWebServer) getMetricsHandler() fasthttp.RequestHandler {
+	return webserver.FastHttpHandlerFromHttpHandler(promhttp.HandlerFor(
+		mws.registry,
+		promhttp.HandlerOpts{
+			EnableOpenMetrics: true,
+		},
+	))
+}

handlers.go

@@ -0,0 +1,56 @@
+package metrics
+
+import (
+	"crypto/subtle"
+	"strings"
+
+	webserver "github.com/randlabs/go-webserver"
+	"github.com/valyala/fasthttp"
+)
+
+// -----------------------------------------------------------------------------
+// Private methods
+
+func (mws *MetricsWebServer) checkAccessToken(ctx *webserver.RequestCtx) bool {
+	if len(mws.accessToken) == 0 {
+		return true
+	}
+
+	var token []byte
+
+	// Get X-Access-Token header
+	header := ctx.Request.Header.Peek("X-Access-Token")
+	if len(header) > 0 {
+		token = header
+	} else {
+		// If no token provided, try with Authorization: Bearer XXX header
+		header = ctx.Request.Header.Peek("Authorization")
+		if len(header) > 0 {
+			auth := strings.SplitN(string(header), " ", 2)
+			if len(auth) == 2 && strings.EqualFold("Bearer", auth[0]) {
+				token = []byte(auth[1])
+			}
+		}
+	}
+
+	//Check token
+	if len(token) > 0 && subtle.ConstantTimeCompare(mws.accessToken, token) != 0 {
+		return true
+	}
+
+	// Deny access
+	return false
+}
+
+func (mws *MetricsWebServer) protectedHandler(handler fasthttp.RequestHandler) fasthttp.RequestHandler {
+	return func(ctx *fasthttp.RequestCtx) {
+		// Check access token
+		if mws.checkAccessToken(ctx) {
+			handler(ctx)
+		} else {
+			webserver.EnableCORS(ctx)
+			webserver.DisableCache(ctx)
+			webserver.SendAccessDenied(ctx, "403 forbidden")
+		}
+	}
+}

handlers_access.go

@@ -0,0 +1,122 @@
+package metrics
+
+// -----------------------------------------------------------------------------
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+	webserver "github.com/randlabs/go-webserver"
+)
+
+// -----------------------------------------------------------------------------
+
+// MetricsWebServer is the metrics web server object
+type MetricsWebServer struct {
+	httpsrv        *webserver.Server
+	registry       *prometheus.Registry
+	healthCallback HealthCallback
+	accessToken    []byte
+}
+
+// Options specifies metrics web server initialization options.
+type Options struct {
+	// Address is the bind address to attach the server listener.
+	Address string
+
+	// Port is the port number the server will listen.
+	Port uint16
+
+	// TLSConfig optionally provides a TLS configuration for use.
+	TLSConfig *tls.Config
+
+	// AccessToken is an optional access token required to access the status endpoints.
+	AccessToken string
+
+	// HealthCallback indicates a function that returns an object that will be returned as a JSON output.
+	HealthCallback HealthCallback
+}
+
+// HealthCallback indicates a function that returns an object that will be returned as a JSON output.
+type HealthCallback func() interface{}
+
+// -----------------------------------------------------------------------------
+
+// CreateMetricsWebServer initializes and creates a new web server
+func CreateMetricsWebServer(opts Options) (*MetricsWebServer, error) {
+	var err error
+
+	if opts.HealthCallback == nil {
+		return nil, errors.New("invalid health callback")
+	}
+
+	// Create metrics object
+	mws := MetricsWebServer{
+		healthCallback: opts.HealthCallback,
+		accessToken:    []byte(opts.AccessToken),
+	}
+
+	// Create webserver
+	mws.httpsrv, err = webserver.Create(webserver.Options{
+		Address:           opts.Address,
+		Port:              opts.Port,
+		EnableCompression: false,
+		TLSConfig:         opts.TLSConfig,
+	})
+	if err != nil {
+		mws.Stop()
+		return nil, fmt.Errorf("unable to create metrics web server [err=%v]", err)
+	}
+
+	// Create Prometheus handler
+	err = mws.createPrometheusRegistry()
+	if err != nil {
+		mws.Stop()
+		return nil, err
+	}
+
+	// Add webserver handlers
+	mws.httpsrv.Router.GET("/health", mws.protectedHandler(mws.getHealthHandler()))
+	mws.httpsrv.Router.GET("/metrics", mws.protectedHandler(mws.getMetricsHandler()))
+	mws.httpsrv.AddProfilerHandlers("/debug/pprof", mws.checkAccessToken)
+
+	// Done
+	return &mws, nil
+}
+
+// Start starts the metrics web server
+func (mws *MetricsWebServer) Start() error {
+	if mws.httpsrv == nil {
+		return errors.New("metrics webserver not initialized")
+	}
+	return mws.httpsrv.Start()
+}
+
+// Stop shuts down the metrics web server
+func (mws *MetricsWebServer) Stop() {
+	// Stop web server
+	if mws.httpsrv != nil {
+		mws.httpsrv.Stop()
+		mws.httpsrv = nil
+	}
+	mws.registry = nil
+
+	mws.cleanAccessToken()
+	mws.healthCallback = nil
+}
+
+// Registry returns the prometheus registry object
+func (mws *MetricsWebServer) Registry() *prometheus.Registry {
+	return mws.registry
+}
+
+// -----------------------------------------------------------------------------
+
+func (mws *MetricsWebServer) cleanAccessToken() {
+	tokenLen := len(mws.accessToken)
+	for idx := 0; idx < tokenLen; idx++ {
+		mws.accessToken[idx] = 0
+	}
+}