chore(melt): add prometheus metrics

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/go-playground/validator/v10 v10.30.1
 	github.com/infisical/go-sdk v0.6.5
 	github.com/joho/godotenv v1.5.1
+	github.com/prometheus/client_golang v1.23.2
 	github.com/puzpuzpuz/xsync/v3 v3.5.1
 	github.com/remychantenay/slog-otel v1.3.4
 	github.com/samber/slog-formatter v1.2.2
@@ -42,6 +43,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.13 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.41.6 // indirect
 	github.com/aws/smithy-go v1.24.0 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
@@ -65,9 +67,13 @@ require (
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
 	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/lufia/plan9stats v0.0.0-20251013123823-9fd1530e3ec3 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/oracle/oci-go-sdk/v65 v65.95.2 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
 	github.com/rs/zerolog v1.26.1 // indirect
 	github.com/samber/lo v1.52.0 // indirect
 	github.com/samber/slog-common v0.19.0 // indirect
@@ -84,6 +90,7 @@ require (
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.39.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.9.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	golang.org/x/crypto v0.47.0 // indirect
 	golang.org/x/mod v0.31.0 // indirect
 	golang.org/x/net v0.49.0 // indirect

go.sum

@@ -36,6 +36,8 @@ github.com/aws/aws-sdk-go-v2/service/sts v1.41.6 h1:5fFjR/ToSOzB2OQ/XqWpZBmNvmP/
 github.com/aws/aws-sdk-go-v2/service/sts v1.41.6/go.mod h1:qgFDZQSD/Kys7nJnVqYlWKnh0SSdMjAi0uSwON4wgYQ=
 github.com/aws/smithy-go v1.24.0 h1:LpilSUItNPFr1eY85RYgTIg5eIEPtvFbskaFcmmIUnk=
 github.com/aws/smithy-go v1.24.0/go.mod h1:LEj2LM3rBRQJxPZTB4KuzZkaZYnZPnvgIhb4pu07mx0=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=
 github.com/cenkalti/backoff/v5 v5.0.3/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
@@ -135,6 +137,8 @@ github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
 github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
 github.com/lufia/plan9stats v0.0.0-20251013123823-9fd1530e3ec3 h1:PwQumkgq4/acIiZhtifTV5OUqqiP82UAl0h87xj/l9k=
 github.com/lufia/plan9stats v0.0.0-20251013123823-9fd1530e3ec3/go.mod h1:autxFIvghDt3jPTLoqZ9OZ7s9qTGNAWmYCjVFWPX/zg=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/oracle/oci-go-sdk/v65 v65.95.2 h1:0HJ0AgpLydp/DtvYrF2d4str2BjXOVAeNbuW7E07g94=
 github.com/oracle/oci-go-sdk/v65 v65.95.2/go.mod h1:u6XRPsw9tPziBh76K7GrrRXPa8P8W3BQeqJ6ZZt9VLA=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -145,7 +149,15 @@ github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRI
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 h1:o4JXh1EVt9k/+g42oCprj/FisM4qX9L3sZB3upGN2ZU=
 github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55/go.mod h1:OmDBASR4679mdNQnz2pUhc2G8CO2JrUAVFDRBDP/hJE=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
+github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
+github.com/prometheus/common v0.66.1 h1:h5E0h5/Y8niHc5DlaLlWLArTQI7tMrsfQjHV+d9ZoGs=
+github.com/prometheus/common v0.66.1/go.mod h1:gcaUsgf3KfRSwHY4dIMXLPV0K/Wg1oZ8+SbZk/HH/dA=
+github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
+github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
 github.com/puzpuzpuz/xsync/v3 v3.5.1 h1:GJYJZwO6IdxN/IKbneznS6yPkVC+c3zyY/j19c++5Fg=
 github.com/puzpuzpuz/xsync/v3 v3.5.1/go.mod h1:VjzYrABPabuM4KyBh1Ftq6u8nhwY5tBPKP9jpmh0nnA=
 github.com/remychantenay/slog-otel v1.3.4 h1:xoM41ayLff2U8zlK5PH31XwD7Lk3W9wKfl4+RcmKom4=
@@ -223,6 +235,8 @@ go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.uber.org/mock v0.6.0 h1:hyF9dfmbgIX5EfOdasqLsWD6xqpNZlXblLB/Dbnwv3Y=
 go.uber.org/mock v0.6.0/go.mod h1:KiVJ4BqZJaMj4svdfmHM0AUx4NJYO8ZNpPnZn1Z+BBU=
+go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
+go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=

melt/prommetric/label.go

@@ -0,0 +1,27 @@
+package prommetric
+
+// Label is a convenient wrapper of anything.
+// Zero Label can provide label names with Labels().
+type Label interface {
+	// Labels returns label names of this Label.
+	// It should be a static slice with fixed length.
+	Labels() []string
+
+	// Values returns values of this Label.
+	// The length is the same as returned by Labels.
+	Values() []string
+}
+
+type NoLabel struct{}
+
+// Labels implements [Label].
+func (n *NoLabel) Labels() []string {
+	return nil
+}
+
+// Values implements [Label].
+func (n *NoLabel) Values() []string {
+	return nil
+}
+
+var _ Label = (*NoLabel)(nil)

melt/prommetric/metrics.go

@@ -0,0 +1,150 @@
+package prommetric
+
+import (
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+type MetricsNoLabel struct {
+	m RecorderWithLabel[*NoLabel]
+}
+
+var _ Recorder = (*MetricsNoLabel)(nil)
+
+func New(prefix, name string, opts ...Option) Recorder {
+	return &MetricsNoLabel{
+		m: NewWithLabel[*NoLabel](prefix, name, opts...),
+	}
+}
+
+// Count implements [Recorder].
+func (m *MetricsNoLabel) Count() Counter {
+	return m.m.Count(nil)
+}
+
+// Duration implements [Recorder].
+func (m *MetricsNoLabel) Duration() DurationObserver {
+	return m.m.Duration(nil)
+}
+
+// Gauge implements [Recorder].
+func (m *MetricsNoLabel) Gauge() Gauge {
+	return m.m.Gauge(nil)
+}
+
+type Metrics[T Label] struct {
+	counter  *prometheus.CounterVec
+	gauge    *prometheus.GaugeVec
+	duration *prometheus.HistogramVec
+}
+
+var _ RecorderWithLabel[*NoLabel] = (*Metrics[*NoLabel])(nil)
+
+func NewWithLabel[T Label](prefix, name string, opts ...Option) RecorderWithLabel[T] {
+	o := &options{
+		buckets:    prometheus.DefBuckets,
+		registerer: prometheus.DefaultRegisterer,
+	}
+	for _, opt := range opts {
+		opt(o)
+	}
+
+	var zeroLabel T
+	factory := promauto.With(o.registerer)
+
+	counter := factory.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: prefix,
+			Name:      name + "_total",
+			Help:      name + " counter",
+		},
+		zeroLabel.Labels(),
+	)
+
+	gauge := factory.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: prefix,
+			Name:      name,
+			Help:      name + " gauge",
+		},
+		zeroLabel.Labels(),
+	)
+
+	duration := factory.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Subsystem: prefix,
+			Name:      name + "_duration_seconds",
+			Help:      name + " duration in seconds",
+			Buckets:   o.buckets,
+		},
+		zeroLabel.Labels(),
+	)
+
+	return &Metrics[T]{
+		duration: duration,
+		gauge:    gauge,
+		counter:  counter,
+	}
+}
+
+// Count implements [RecorderWithLabel].
+func (m *Metrics[T]) Count(label T) Counter {
+	c := m.counter.WithLabelValues(label.Values()...)
+	return &counter{c}
+}
+
+type counter struct {
+	c prometheus.Counter
+}
+
+// Add implements [Counter].
+func (c *counter) Add(val float64) {
+	c.c.Add(val)
+}
+
+// Inc implements [Counter].
+func (c *counter) Inc() {
+	c.c.Inc()
+}
+
+// Duration implements [RecorderWithLabel].
+func (m *Metrics[T]) Duration(label T) DurationObserver {
+	h := m.duration.WithLabelValues(label.Values()...)
+	return &durationObserver{h}
+}
+
+type durationObserver struct {
+	h prometheus.Observer
+}
+
+// Observe implements [DurationObserver].
+func (d *durationObserver) Observe(dur time.Duration) {
+	d.h.Observe(dur.Seconds())
+}
+
+// Gauge implements [RecorderWithLabel].
+func (m *Metrics[T]) Gauge(label T) Gauge {
+	g := m.gauge.WithLabelValues(label.Values()...)
+	return &gauge{g}
+}
+
+type gauge struct {
+	g prometheus.Gauge
+}
+
+// Set implements [Gauge].
+func (g *gauge) Set(val float64) { g.g.Set(val) }
+
+// Inc implements [Gauge].
+func (g *gauge) Inc() { g.g.Inc() }
+
+// Dec implements [Gauge].
+func (g *gauge) Dec() { g.g.Dec() }
+
+// Add implements [Gauge].
+func (g *gauge) Add(val float64) { g.g.Add(val) }
+
+// Sub implements [Gauge].
+func (g *gauge) Sub(val float64) { g.g.Sub(val) }

melt/prommetric/options.go

@@ -0,0 +1,22 @@
+package prommetric
+
+import "github.com/prometheus/client_golang/prometheus"
+
+type options struct {
+	buckets    []float64
+	registerer prometheus.Registerer
+}
+
+type Option func(*options)
+
+func WithBuckets(buckets []float64) Option {
+	return func(o *options) {
+		o.buckets = buckets
+	}
+}
+
+func WithRegisterer(r prometheus.Registerer) Option {
+	return func(o *options) {
+		o.registerer = r
+	}
+}

melt/prommetric/recorder.go

@@ -0,0 +1,33 @@
+package prommetric
+
+import (
+	"time"
+)
+
+type Recorder interface {
+	Count() Counter
+	Duration() DurationObserver
+	Gauge() Gauge
+}
+type RecorderWithLabel[T Label] interface {
+	Count(label T) Counter
+	Duration(label T) DurationObserver
+	Gauge(label T) Gauge
+}
+
+type Counter interface {
+	Inc()
+	Add(val float64)
+}
+
+type DurationObserver interface {
+	Observe(duration time.Duration)
+}
+
+type Gauge interface {
+	Set(val float64)
+	Inc()
+	Dec()
+	Add(val float64)
+	Sub(val float64)
+}