Implement Prometheus remote write receiver compatible with sfx gateway

examples/signalfxgatewayprometheusremotewritereceiver/Dockerfile.fake-metrics-generator

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+FROM golang:1.19-alpine AS builder
+WORKDIR /app
+COPY fake-metrics-generator.go go.mod go.sum ./
+RUN CGO_ENABLED=0 GOOS=linux go build -o fake-metrics-generator
+
+FROM alpine:3.14
+WORKDIR /app
+COPY --from=builder /app/fake-metrics-generator .
+CMD ["./fake-metrics-generator"]

examples/signalfxgatewayprometheusremotewritereceiver/Makefile

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+include ../../Makefile.Common

examples/signalfxgatewayprometheusremotewritereceiver/README.md

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+# SignalFx Gateway Prometheus Remote write Receiver Example
+
+This example provides a `docker-compose` environment that continually sends some fake prometheus remote writes to an otel receiver replacement for the deprecated SignalFx Gateway for Prometheus Remote Writes.
+To run this, ensure you have `docker-compose` installed. 
+
+## Configuration
+You can change the exporters to your liking by modifying `otel-collector-config.yaml`.
+
+Ensure the following environment variables are properly set, should you wish to send data to splunk observability cloud:
+1. `SPLUNK_ACCESS_TOKEN`
+2. `SPLUNK_REALM`
+
+Alternatively, you can remove the `signalfx` array item from the `exporters` configuration map in `otel-collector-config.yaml`
+
+Feel free to modify the sample client to your liking, or even disable it and write your own!
+
+## Running
+Once you've verified your environment, you can run the example by
+
+```bash
+$> docker-compose up
+```
+
+If everything is configured properly, logs with sample writes should start appearing in stdout shortly.

examples/signalfxgatewayprometheusremotewritereceiver/docker-compose.yml

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+version: "3.1"
+services:
+  otelcollector:
+    image:  otelcol:latest
+    container_name: otelcollector
+    environment:
+      - SPLUNK_ACCESS_TOKEN=${SPLUNK_ACCESS_TOKEN}
+      - SPLUNK_REALM=${SPLUNK_REALM}
+    command: ["--config=/etc/otel-collector-config.yaml", "--set=service.telemetry.logs.level=debug"]
+    volumes:
+      - ./otel-collector-config.yaml:/etc/otel-collector-config.yaml
+    ports:
+      - "19291:19291"
+      - "8888:8888"
+
+  fake_metrics_generator:
+    build:
+      context: .
+      dockerfile: Dockerfile.fake-metrics-generator
+    depends_on:
+      - otelcollector
+    environment:
+      - TARGET_URL=http://otelcollector:19291/metrics

examples/signalfxgatewayprometheusremotewritereceiver/fake-metrics-generator.go

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+// Copyright OpenTelemetry Authors
+// Copyright Splunk, Inc.
+//
+// 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 main
+
+import (
+	"context"
+	"net/url"
+	"os"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+	"github.com/golang/snappy"
+	"github.com/prometheus/common/config"
+	"github.com/prometheus/prometheus/prompb"
+	"github.com/prometheus/prometheus/storage/remote"
+)
+
+func main() {
+
+	URL := &config.URL{
+		URL: &url.URL{
+			Scheme: "http",
+			Host:   os.Getenv("endpoint"),
+			Path:   os.Getenv("path"),
+		},
+	}
+	cfg := &remote.ClientConfig{
+		URL:              URL,
+		HTTPClientConfig: config.HTTPClientConfig{},
+	}
+	client, err := remote.NewWriteClient("mock_prw_client", cfg)
+	if err != nil {
+		panic(err)
+	}
+
+	metrics := []prompb.TimeSeries{
+		{
+			Labels: []prompb.Label{
+				{Name: "__name__", Value: "fake_metric_total"},
+				{Name: "instance", Value: cfg.URL.Host},
+			},
+			Samples: []prompb.Sample{
+				{Value: 42, Timestamp: time.Now().UnixMilli()},
+			},
+		},
+	}
+
+	req := &prompb.WriteRequest{
+		Timeseries: metrics,
+	}
+	compressed := encodeWriteRequest(req)
+
+	for {
+		client.Store(context.Background(), compressed)
+		time.Sleep(10 * time.Second)
+	}
+}
+
+func encodeWriteRequest(request *prompb.WriteRequest) []byte {
+	data, err := proto.Marshal(request)
+	if err != nil {
+		panic(err)
+	}
+
+	return snappy.Encode(nil, data)
+}

examples/signalfxgatewayprometheusremotewritereceiver/go.mod

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+module fake-metrics-generator
+
+go 1.19
+
+require (
+	github.com/gogo/protobuf v1.3.2
+	github.com/golang/snappy v0.0.4
+	github.com/prometheus/common v0.42.0
+	github.com/prometheus/prometheus v0.43.1
+)
+
+require (
+	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 // indirect
+	github.com/aws/aws-sdk-go v1.44.217 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dennwc/varint v1.0.0 // indirect
+	github.com/felixge/httpsnoop v1.0.3 // indirect
+	github.com/go-kit/log v0.2.1 // indirect
+	github.com/go-logfmt/logfmt v0.6.0 // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/grafana/regexp v0.0.0-20221122212121-6b5c0a4cb7fd // indirect
+	github.com/jmespath/go-jmespath v0.4.0 // indirect
+	github.com/jpillora/backoff v1.0.0 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_golang v1.14.0 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common/sigv4 v0.1.0 // indirect
+	github.com/prometheus/procfs v0.9.0 // indirect
+	github.com/stretchr/testify v1.8.2 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.40.0 // indirect
+	go.opentelemetry.io/otel v1.14.0 // indirect
+	go.opentelemetry.io/otel/metric v0.37.0 // indirect
+	go.opentelemetry.io/otel/trace v1.14.0 // indirect
+	go.uber.org/atomic v1.10.0 // indirect
+	go.uber.org/goleak v1.2.1 // indirect
+	golang.org/x/exp v0.0.0-20230307190834-24139beb5833 // indirect
+	golang.org/x/net v0.8.0 // indirect
+	golang.org/x/oauth2 v0.6.0 // indirect
+	golang.org/x/sys v0.6.0 // indirect
+	golang.org/x/text v0.8.0 // indirect
+	golang.org/x/time v0.3.0 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/protobuf v1.29.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)