Add HTTP metrics exporter for OTLP

.github/dependabot.yml

@@ -316,3 +316,13 @@ updates:
     schedule:
       day: sunday
       interval: weekly
+  -
+    package-ecosystem: gomod
+    directory: /exporters/otlp/otlpmetric/otlpmetrichttp
+    labels:
+      - dependencies
+      - go
+      - "Skip Changelog"
+    schedule:
+      day: sunday
+      interval: weekly

CHANGELOG.md

@@ -10,6 +10,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Added
 
+- Adds HTTP support for OTLP metrics exporter. (#2022)
+
 ### Changed
 
 ### Deprecated

bridge/opencensus/go.mod

@@ -69,3 +69,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

bridge/opentracing/go.mod

@@ -65,3 +65,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/jaeger/go.mod

@@ -65,3 +65,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/namedtracer/go.mod

@@ -67,3 +67,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/opencensus/go.mod

@@ -69,3 +69,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/otel-collector/go.mod

@@ -68,3 +68,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/passthrough/go.mod

@@ -68,3 +68,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/prometheus/go.mod

@@ -67,3 +67,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

example/zipkin/go.mod

@@ -66,3 +66,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../exporters/stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../exporters/stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../../exporters/otlp/otlpmetric/otlpmetrichttp

exporters/jaeger/go.mod

@@ -69,3 +69,5 @@ replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc => ../
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../otlp/otlpmetric/otlpmetrichttp

exporters/otlp/otlpmetric/go.mod

@@ -75,3 +75,5 @@ replace go.opentelemetry.io/otel/exporters/zipkin => ../../zipkin
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ./otlpmetrichttp

exporters/otlp/otlpmetric/internal/otlpconfig/options.go

@@ -24,9 +24,16 @@ import (
 )
 
 const (
+	// DefaultMaxAttempts describes how many times the driver
+	// should retry the sending of the payload in case of a
+	// retryable error.
+	DefaultMaxAttempts int = 5
 	// DefaultMetricsPath is a default URL path for endpoint that
 	// receives metrics.
 	DefaultMetricsPath string = "/v1/metrics"
+	// DefaultBackoff is a default base backoff time used in the
+	// exponential backoff strategy.
+	DefaultBackoff time.Duration = 300 * time.Millisecond
 	// DefaultTimeout is a default max waiting time for the backend to process
 	// each span or metrics batch.
 	DefaultTimeout time.Duration = 10 * time.Second
@@ -60,6 +67,10 @@ type (
 		// Signal specific configurations
 		Metrics SignalConfig
 
+		// HTTP configurations
+		MaxAttempts int
+		Backoff     time.Duration
+
 		// gRPC configurations
 		ReconnectionPeriod time.Duration
 		ServiceConfig      string
@@ -243,3 +254,15 @@ func WithTimeout(duration time.Duration) GenericOption {
 		cfg.Metrics.Timeout = duration
 	})
 }
+
+func WithMaxAttempts(maxAttempts int) GenericOption {
+	return newGenericOption(func(cfg *Config) {
+		cfg.MaxAttempts = maxAttempts
+	})
+}
+
+func WithBackoff(duration time.Duration) GenericOption {
+	return newGenericOption(func(cfg *Config) {
+		cfg.Backoff = duration
+	})
+}

exporters/otlp/otlpmetric/internal/otlpconfig/options_test.go

@@ -321,6 +321,19 @@ func TestConfigs(t *testing.T) {
 				assert.Equal(t, otlpconfig.GzipCompression, c.Metrics.Compression)
 			},
 		},
+		{
+			name: "Test Mixed Environment and With Compression",
+			opts: []otlpconfig.GenericOption{
+				otlpconfig.WithCompression(otlpconfig.NoCompression),
+			},
+			env: map[string]string{
+				"OTEL_EXPORTER_OTLP_METRICS_COMPRESSION": "gzip",
+			},
+			asserts: func(t *testing.T, c *otlpconfig.Config, grpcOption bool) {
+				assert.Equal(t, otlpconfig.NoCompression, c.Metrics.Compression)
+			},
+		},
+
 		// Timeout Tests
 		{
 			name: "Test With Timeout",

exporters/otlp/otlpmetric/otlpmetricgrpc/go.mod

@@ -73,3 +73,5 @@ replace go.opentelemetry.io/otel/exporters/zipkin => ../../../zipkin
 replace go.opentelemetry.io/otel/exporters/stdout/stdoutmetric => ../../../stdout/stdoutmetric
 
 replace go.opentelemetry.io/otel/exporters/stdout/stdouttrace => ../../../stdout/stdouttrace
+
+replace go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp => ../otlpmetrichttp

exporters/otlp/otlpmetric/otlpmetrichttp/certificate_test.go

@@ -0,0 +1,92 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package otlpmetrichttp_test
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	cryptorand "crypto/rand"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"math/big"
+	mathrand "math/rand"
+	"net"
+	"time"
+)
+
+type mathRandReader struct{}
+
+func (mathRandReader) Read(p []byte) (n int, err error) {
+	return mathrand.Read(p)
+}
+
+var randReader mathRandReader
+
+type pemCertificate struct {
+	Certificate []byte
+	PrivateKey  []byte
+}
+
+// Based on https://golang.org/src/crypto/tls/generate_cert.go,
+// simplified and weakened.
+func generateWeakCertificate() (*pemCertificate, error) {
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), randReader)
+	if err != nil {
+		return nil, err
+	}
+	keyUsage := x509.KeyUsageDigitalSignature
+	notBefore := time.Now()
+	notAfter := notBefore.Add(time.Hour)
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := cryptorand.Int(randReader, serialNumberLimit)
+	if err != nil {
+		return nil, err
+	}
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"otel-go"},
+		},
+		NotBefore:             notBefore,
+		NotAfter:              notAfter,
+		KeyUsage:              keyUsage,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		DNSNames:              []string{"localhost"},
+		IPAddresses:           []net.IP{net.IPv6loopback, net.IPv4(127, 0, 0, 1)},
+	}
+	derBytes, err := x509.CreateCertificate(randReader, &template, &template, &priv.PublicKey, priv)
+	if err != nil {
+		return nil, err
+	}
+	certificateBuffer := new(bytes.Buffer)
+	if err := pem.Encode(certificateBuffer, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
+		return nil, err
+	}
+	privDERBytes, err := x509.MarshalPKCS8PrivateKey(priv)
+	if err != nil {
+		return nil, err
+	}
+	privBuffer := new(bytes.Buffer)
+	if err := pem.Encode(privBuffer, &pem.Block{Type: "PRIVATE KEY", Bytes: privDERBytes}); err != nil {
+		return nil, err
+	}
+	return &pemCertificate{
+		Certificate: certificateBuffer.Bytes(),
+		PrivateKey:  privBuffer.Bytes(),
+	}, nil
+}