config: NewSDK can return valid MeterProvider

Follow up to #4741, does the same but for metric signal.

Fixes #4371

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

CHANGELOG.md

@@ -11,6 +11,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Added
 
 - Add the new `go.opentelemetry.io/contrib/instrgen` package to provide auto-generated source code instrumentation. (#3068, #3108)
+- `NewSDK` in `go.opentelemetry.io/contrib/config` now returns a configured SDK with a valid `MeterProvider`. (#4804)
 
 ### Removed
 

config/config.go

@@ -67,7 +67,11 @@ func NewSDK(opts ...ConfigurationOption) (SDK, error) {
 		return SDK{}, err
 	}
 
-	mp, mpShutdown := initMeterProvider(o)
+	mp, mpShutdown, err := meterProvider(o, r)
+	if err != nil {
+		return SDK{}, err
+	}
+
 	tp, tpShutdown, err := tracerProvider(o, r)
 	if err != nil {
 		return SDK{}, err

config/go.mod

@@ -3,10 +3,15 @@ module go.opentelemetry.io/contrib/config
 go 1.21
 
 require (
+	github.com/prometheus/client_golang v1.19.0
 	github.com/stretchr/testify v1.9.0
 	go.opentelemetry.io/otel v1.24.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.24.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.24.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.24.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0
+	go.opentelemetry.io/otel/exporters/prometheus v0.46.0
+	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.24.0
 	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.24.0
 	go.opentelemetry.io/otel/metric v1.24.0
 	go.opentelemetry.io/otel/sdk v1.24.0
@@ -15,13 +20,18 @@ require (
 )
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-logr/logr v1.4.1 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.19.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.6.0 // indirect
+	github.com/prometheus/common v0.48.0 // indirect
+	github.com/prometheus/procfs v0.12.0 // indirect
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.24.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.1.0 // indirect
 	golang.org/x/net v0.21.0 // indirect

config/go.sum

@@ -1,5 +1,9 @@
+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/v4 v4.2.1 h1:y4OZtCnogmCPw98Zjyt5a6+QwPLGkiQsYW5oUqylYbM=
 github.com/cenkalti/backoff/v4 v4.2.1/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
@@ -21,18 +25,34 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
-github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
+github.com/prometheus/client_golang v1.19.0 h1:ygXvpU1AoN1MhdzckN+PyD9QJOSD4x7kmXYlnfbA6JU=
+github.com/prometheus/client_golang v1.19.0/go.mod h1:ZRM9uEAypZakd+q/x7+gmsvXdURP+DABIEIjnmDdp+k=
+github.com/prometheus/client_model v0.6.0 h1:k1v3CzpSRUTrKMppY35TLwPvxHqBu0bYgxZzqGIgaos=
+github.com/prometheus/client_model v0.6.0/go.mod h1:NTQHnmxFpouOD0DpvP4XujX3CdOAGQPoaGhyTchlyt8=
+github.com/prometheus/common v0.48.0 h1:QO8U2CdOzSn1BBsmXJXduaaW+dY/5QLjfB8svtSzKKE=
+github.com/prometheus/common v0.48.0/go.mod h1:0/KsvlIEfPQCQ5I2iNSAWKPZziNCvRs5EC6ILDTlAPc=
+github.com/prometheus/procfs v0.12.0 h1:jluTpSng7V9hY0O2R9DzzJHYb2xULk9VTR1V1R/k6Bo=
+github.com/prometheus/procfs v0.12.0/go.mod h1:pcuDEFsWDnvcgNzo4EEweacyhjeA9Zk3cnaOZAZEfOo=
+github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M=
+github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 go.opentelemetry.io/otel v1.24.0 h1:0LAOdjNmQeSTzGBzduGe/rU4tZhMwL5rWgtp9Ku5Jfo=
 go.opentelemetry.io/otel v1.24.0/go.mod h1:W7b9Ozg4nkF5tWI5zsXkaKKDjdVjpD4oAt9Qi/MArHo=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.24.0 h1:f2jriWfOdldanBwS9jNBdeOKAQN7b4ugAMaNu1/1k9g=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.24.0/go.mod h1:B+bcQI1yTY+N0vqMpoZbEN7+XU4tNM0DmUiOwebFJWI=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.24.0 h1:mM8nKi6/iFQ0iqst80wDHU2ge198Ye/TfN0WBS5U24Y=
+go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.24.0/go.mod h1:0PrIIzDteLSmNyxqcGYRL4mDIo8OTuBAOI/Bn1URxac=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.24.0 h1:t6wl9SPayj+c7lEIFgm4ooDBZVb01IhLB4InpomhRw8=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.24.0/go.mod h1:iSDOcsnSA5INXzZtwaBPrKp/lWu/V14Dd+llD0oI2EA=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.24.0 h1:Mw5xcxMwlqoJd97vwPxA8isEaIoxsta9/Q51+TTJLGE=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.24.0/go.mod h1:CQNu9bj7o7mC6U7+CA/schKEYakYXWr79ucDHTMGhCM=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0 h1:Xw8U6u2f8DK2XAkGRFV7BBLENgnTGX9i4rQRxJf+/vs=
 go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.24.0/go.mod h1:6KW1Fm6R/s6Z3PGXwSJN2K4eT6wQB3vXX6CVnYX9NmM=
+go.opentelemetry.io/otel/exporters/prometheus v0.46.0 h1:I8WIFXR351FoLJYuloU4EgXbtNX2URfU/85pUPheIEQ=
+go.opentelemetry.io/otel/exporters/prometheus v0.46.0/go.mod h1:ztwVUHe5DTR/1v7PeuGRnU5Bbd4QKYwApWmuutKsJSs=
+go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.24.0 h1:JYE2HM7pZbOt5Jhk8ndWZTUWYOVift2cHjXVMkPdmdc=
+go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.24.0/go.mod h1:yMb/8c6hVsnma0RpsBMNo0fEiQKeclawtgaIaOp2MLY=
 go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.24.0 h1:s0PHtIkN+3xrbDOpt2M8OTG92cWqUESvzh2MxiR5xY8=
 go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.24.0/go.mod h1:hZlFbDbRt++MMPCCfSJfmhkGIWnX1h3XjkfxZUjLrIA=
 go.opentelemetry.io/otel/metric v1.24.0 h1:6EhoGWWK28x1fbpA4tYTOWBkPefTDQnb8WSGXlc88kI=

config/metric.go

@@ -4,15 +4,257 @@
 package config // import "go.opentelemetry.io/contrib/config"
 
 import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
+	otelprom "go.opentelemetry.io/otel/exporters/prometheus"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/noop"
 	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
 )
 
-func initMeterProvider(cfg configOptions) (metric.MeterProvider, shutdownFunc) {
+func meterProvider(cfg configOptions, res *resource.Resource) (metric.MeterProvider, shutdownFunc, error) {
 	if cfg.opentelemetryConfig.MeterProvider == nil {
-		return noop.NewMeterProvider(), noopShutdown
+		return noop.NewMeterProvider(), noopShutdown, nil
+	}
+	opts := []sdkmetric.Option{
+		sdkmetric.WithResource(res),
+	}
+
+	var errs []error
+	for _, reader := range cfg.opentelemetryConfig.MeterProvider.Readers {
+		r, err := metricReader(cfg.ctx, reader)
+		if err == nil {
+			opts = append(opts, sdkmetric.WithReader(r))
+		} else {
+			errs = append(errs, err)
+		}
+	}
+	if len(errs) > 0 {
+		return noop.NewMeterProvider(), noopShutdown, errors.Join(errs...)
+	}
+
+	mp := sdkmetric.NewMeterProvider(opts...)
+	return mp, mp.Shutdown, nil
+}
+
+func metricReader(ctx context.Context, r MetricReader) (sdkmetric.Reader, error) {
+	if r.Periodic != nil && r.Pull != nil {
+		return nil, errors.New("must not specify multiple metric reader type")
+	}
+
+	if r.Periodic != nil {
+		return periodicExporter(ctx, r.Periodic.Exporter)
+	}
+
+	if r.Pull != nil {
+		return pullReader(ctx, r.Pull.Exporter)
+	}
+	return nil, errors.New("no valid metric reader")
+}
+
+func pullReader(ctx context.Context, exporter MetricExporter) (sdkmetric.Reader, error) {
+	if exporter.Prometheus != nil {
+		return prometheusReader(ctx, exporter.Prometheus)
+	}
+	return nil, errors.New("no valid metric exporter")
+}
+
+func periodicExporter(ctx context.Context, exporter MetricExporter, opts ...sdkmetric.PeriodicReaderOption) (sdkmetric.Reader, error) {
+	if exporter.Console != nil && exporter.OTLP != nil {
+		return nil, errors.New("must not specify multiple exporters")
+	}
+	if exporter.Console != nil {
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+
+		exp, err := stdoutmetric.New(
+			stdoutmetric.WithEncoder(enc),
+		)
+		if err != nil {
+			return nil, err
+		}
+		return sdkmetric.NewPeriodicReader(exp, opts...), nil
+	}
+	if exporter.OTLP != nil {
+		var err error
+		var exp sdkmetric.Exporter
+		switch exporter.OTLP.Protocol {
+		case protocolProtobufHTTP:
+			exp, err = otlpHTTPMetricExporter(ctx, exporter.OTLP)
+		case protocolProtobufGRPC:
+			exp, err = otlpGRPCMetricExporter(ctx, exporter.OTLP)
+		default:
+			return nil, fmt.Errorf("unsupported protocol %q", exporter.OTLP.Protocol)
+		}
+		if err != nil {
+			return nil, err
+		}
+		return sdkmetric.NewPeriodicReader(exp, opts...), nil
+	}
+	return nil, errors.New("no valid metric exporter")
+}
+
+func otlpHTTPMetricExporter(ctx context.Context, otlpConfig *OTLPMetric) (sdkmetric.Exporter, error) {
+	opts := []otlpmetrichttp.Option{}
+
+	if len(otlpConfig.Endpoint) > 0 {
+		u, err := url.ParseRequestURI(otlpConfig.Endpoint)
+		if err != nil {
+			return nil, err
+		}
+		opts = append(opts, otlpmetrichttp.WithEndpoint(u.Host))
+
+		if u.Scheme == "http" {
+			opts = append(opts, otlpmetrichttp.WithInsecure())
+		}
+		if len(u.Path) > 0 {
+			opts = append(opts, otlpmetrichttp.WithURLPath(u.Path))
+		}
+	}
+	if otlpConfig.Compression != nil {
+		switch *otlpConfig.Compression {
+		case compressionGzip:
+			opts = append(opts, otlpmetrichttp.WithCompression(otlpmetrichttp.GzipCompression))
+		case compressionNone:
+			opts = append(opts, otlpmetrichttp.WithCompression(otlpmetrichttp.NoCompression))
+		default:
+			return nil, fmt.Errorf("unsupported compression %q", *otlpConfig.Compression)
+		}
+	}
+	if otlpConfig.Timeout != nil {
+		opts = append(opts, otlpmetrichttp.WithTimeout(time.Millisecond*time.Duration(*otlpConfig.Timeout)))
 	}
-	mp := sdkmetric.NewMeterProvider()
-	return mp, mp.Shutdown
+	if len(otlpConfig.Headers) > 0 {
+		opts = append(opts, otlpmetrichttp.WithHeaders(otlpConfig.Headers))
+	}
+
+	return otlpmetrichttp.New(ctx, opts...)
+}
+
+func otlpGRPCMetricExporter(ctx context.Context, otlpConfig *OTLPMetric) (sdkmetric.Exporter, error) {
+	opts := []otlpmetricgrpc.Option{}
+
+	if len(otlpConfig.Endpoint) > 0 {
+		u, err := url.ParseRequestURI(otlpConfig.Endpoint)
+		if err != nil {
+			return nil, err
+		}
+		// ParseRequestURI leaves the Host field empty when no
+		// scheme is specified (i.e. localhost:4317). This check is
+		// here to support the case where a user may not specify a
+		// scheme. The code does its best effort here by using
+		// otlpConfig.Endpoint as-is in that case
+		if u.Host != "" {
+			opts = append(opts, otlpmetricgrpc.WithEndpoint(u.Host))
+		} else {
+			opts = append(opts, otlpmetricgrpc.WithEndpoint(otlpConfig.Endpoint))
+		}
+		if u.Scheme == "http" {
+			opts = append(opts, otlpmetricgrpc.WithInsecure())
+		}
+	}
+
+	if otlpConfig.Compression != nil {
+		switch *otlpConfig.Compression {
+		case compressionGzip:
+			opts = append(opts, otlpmetricgrpc.WithCompressor(*otlpConfig.Compression))
+		case compressionNone:
+			// none requires no options
+		default:
+			return nil, fmt.Errorf("unsupported compression %q", *otlpConfig.Compression)
+		}
+	}
+	if otlpConfig.Timeout != nil && *otlpConfig.Timeout > 0 {
+		opts = append(opts, otlpmetricgrpc.WithTimeout(time.Millisecond*time.Duration(*otlpConfig.Timeout)))
+	}
+	if len(otlpConfig.Headers) > 0 {
+		opts = append(opts, otlpmetricgrpc.WithHeaders(otlpConfig.Headers))
+	}
+
+	return otlpmetricgrpc.New(ctx, opts...)
+}
+
+func prometheusReader(ctx context.Context, prometheusConfig *Prometheus) (sdkmetric.Reader, error) {
+	var opts []otelprom.Option
+	if prometheusConfig.Host == nil {
+		return nil, fmt.Errorf("host must be specified")
+	}
+	if prometheusConfig.Port == nil {
+		return nil, fmt.Errorf("port must be specified")
+	}
+	if prometheusConfig.WithoutScopeInfo != nil && *prometheusConfig.WithoutScopeInfo {
+		opts = append(opts, otelprom.WithoutScopeInfo())
+	}
+	if prometheusConfig.WithoutTypeSuffix != nil && *prometheusConfig.WithoutTypeSuffix {
+		opts = append(opts, otelprom.WithoutCounterSuffixes())
+	}
+	if prometheusConfig.WithoutUnits != nil && *prometheusConfig.WithoutUnits {
+		opts = append(opts, otelprom.WithoutUnits())
+	}
+
+	reg := prometheus.NewRegistry()
+	opts = append(opts, otelprom.WithRegisterer(reg))
+
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.HandlerFor(reg, promhttp.HandlerOpts{Registry: reg}))
+	server := http.Server{
+		// Timeouts are necessary to make a server resilent to attacks, but ListenAndServe doesn't set any.
+		// We use values from this example: https://blog.cloudflare.com/exposing-go-on-the-internet/#:~:text=There%20are%20three%20main%20timeouts
+		ReadTimeout:  5 * time.Second,
+		WriteTimeout: 10 * time.Second,
+		IdleTimeout:  120 * time.Second,
+		Handler:      mux,
+	}
+	addr := fmt.Sprintf("%s:%d", *prometheusConfig.Host, *prometheusConfig.Port)
+
+	// TODO: add support for constant label filter
+	// 	otelprom.WithResourceAsConstantLabels(attribute.NewDenyKeysFilter()),
+	// )
+	reader, err := otelprom.New(opts...)
+	if err != nil {
+		return nil, fmt.Errorf("error creating otel prometheus exporter: %w", err)
+	}
+	lis, err := net.Listen("tcp", addr)
+	if err != nil {
+		return nil, errors.Join(
+			fmt.Errorf("binding address %s for Prometheus exporter: %w", addr, err),
+			reader.Shutdown(ctx),
+		)
+	}
+
+	go func() {
+		if err := server.Serve(lis); err != nil && err != http.ErrServerClosed {
+			otel.Handle(fmt.Errorf("the Prometheus HTTP server exited unexpectedly: %w", err))
+		}
+	}()
+
+	return readerWithServer{reader, &server}, nil
+}
+
+type readerWithServer struct {
+	sdkmetric.Reader
+	server *http.Server
+}
+
+func (rws readerWithServer) Shutdown(ctx context.Context) error {
+	return errors.Join(
+		rws.Reader.Shutdown(ctx),
+		rws.server.Shutdown(ctx),
+	)
 }