For Code Review: All files

exporter/prometheusremotewriteexporter/README.md

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+This Exporter sends metrics data in Prometheus TimeSeries format to any Prometheus Remote Write compatible backend, such as Cortex.
+
+Non-cumulative monotonic, histogram, and summary OTLP metrics are dropped by this exporter. 
+
+The following settings are required:
+
+- `endpoint`: protocol:host:port to which the exporter is going to send traces or metrics, using 
+the HTTP/HTTPS protocol. 
+
+- `namespace`: suffix to metric name attached to each metric.
+
+The following settings can be optionally configured:
+- `headers`: additional headers attached to each HTTP request. `X-Prometheus-Remote-Write-Version` cannot be set by users
+and is attached to each request. 
+- `insecure` (default = false): whether to enable client transport security for
+  the exporter's connection.
+- `ca_file`: path to the CA cert. For a client this verifies the server certificate. Should
+  only be used if `insecure` is set to true.
+- `cert_file`: path to the TLS cert to use for TLS required connections. Should
+  only be used if `insecure` is set to true.
+- `key_file`: path to the TLS key to use for TLS required connections. Should
+  only be used if `insecure` is set to true.
+- `timeout` (default = 5s): How long to wait until the connection is close.
+- `read_buffer_size` (default = 0): ReadBufferSize for HTTP client.
+- `write_buffer_size` (default = 512 * 1024): WriteBufferSize for HTTP client.
+
+Example:
+
+```yaml
+exporters:
+prometheusremotewrite:
+ endpoint: "http://some.url:9411/api/prom/push"
+```
+The full list of settings exposed for this exporter are documented [here](./config.go)
+with detailed sample configurations [here](./testdata/config.yaml).
+
+_Here is a link to the overall project [design](https://github.com/open-telemetry/opentelemetry-collector/pull/1464)_
+
+File structure:
+
+- `cortex.go`: exporter implementation. Converts and sends OTLP metrics
+
+- `helper.go`: helper functions that cortex.go uses. Performs tasks such as sanitizing label and generating signature string
+
+- `config.go`: configuration struct of the exporter
+
+- `factory.go`: initialization methods for creating default configuration and the exporter
+
+Feature in development:  derive Prometheus `job` or `instance` label from Resource, or allow users to configure which Resource attributes needs to be added as metric label_

exporter/prometheusremotewriteexporter/config.go

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+// Copyright 2020 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.
+
+// This package defines the standard and necessary parameters of the exporter config struct.
+// The yaml file for the entire collector pipelne must include a section underneath
+// `exporters` titled `prometheusremotewrite(/#)`. Example in testdata/config.yaml.
+
+package prometheusremotewriteexporter
+
+import (
+	"go.opentelemetry.io/collector/config/confighttp"
+	"go.opentelemetry.io/collector/config/configmodels"
+	"go.opentelemetry.io/collector/exporter/exporterhelper"
+)
+
+// Config defines configuration for Remote Write exporter.
+type Config struct {
+	// squash ensures fields are correctly decoded in embedded struct.
+	configmodels.ExporterSettings  `mapstructure:",squash"`
+	exporterhelper.TimeoutSettings `mapstructure:",squash"`
+
+	exporterhelper.QueueSettings `mapstructure:"sending_queue"`
+	exporterhelper.RetrySettings `mapstructure:"retry_on_failure"`
+
+	// Namespace if set, exports metrics under the provided value.*/
+	Namespace string `mapstructure:"namespace"`
+
+	// Optional headers configuration for authorization and security/extra metadata
+	Headers map[string]string `mapstructure:"headers"`
+
+	HTTPClientSettings confighttp.HTTPClientSettings `mapstructure:"http_setting"`
+}

exporter/prometheusremotewriteexporter/config_test.go

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+// Copyright 2020 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 prometheusremotewriteexporter
+
+import (
+	"path"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"go.opentelemetry.io/collector/component/componenttest"
+	"go.opentelemetry.io/collector/config/confighttp"
+	"go.opentelemetry.io/collector/config/configmodels"
+	"go.opentelemetry.io/collector/config/configtest"
+	"go.opentelemetry.io/collector/config/configtls"
+	"go.opentelemetry.io/collector/exporter/exporterhelper"
+)
+
+// TestLoadConfig checks whether yaml configuration can be loaded correctly
+func TestLoadConfig(t *testing.T) {
+	factories, err := componenttest.ExampleComponents()
+	assert.NoError(t, err)
+
+	factory := NewFactory()
+	factories.Exporters[typeStr] = factory
+	cfg, err := configtest.LoadConfigFile(t, path.Join(".", "testdata", "config.yaml"), factories)
+
+	require.NoError(t, err)
+	require.NotNil(t, cfg)
+
+	// From the default configurations -- checks if a correct exporter is instantiated
+	e0 := cfg.Exporters["prometheusremotewrite"]
+	assert.Equal(t, e0, factory.CreateDefaultConfig())
+
+	// checks if the correct Config struct can be instantiated from testdata/config.yaml
+	e1 := cfg.Exporters["prometheusremotewrite/2"]
+	assert.Equal(t, e1,
+		&Config{
+			ExporterSettings: configmodels.ExporterSettings{
+				NameVal: "prometheusremotewrite/2",
+				TypeVal: "prometheusremotewrite",
+			},
+			TimeoutSettings: exporterhelper.TimeoutSettings{
+				Timeout: 10 * time.Second,
+			},
+			QueueSettings: exporterhelper.QueueSettings{
+				Enabled:      true,
+				NumConsumers: 2,
+				QueueSize:    10,
+			},
+			RetrySettings: exporterhelper.RetrySettings{
+				Enabled:         true,
+				InitialInterval: 10 * time.Second,
+				MaxInterval:     1 * time.Minute,
+				MaxElapsedTime:  10 * time.Minute,
+			},
+			Namespace: "test-space",
+
+			Headers: map[string]string{
+				"prometheus-remote-write-version": "0.1.0",
+				"tenant-id":                       "234"},
+
+			HTTPClientSettings: confighttp.HTTPClientSettings{
+				Endpoint: "localhost:8888",
+				TLSSetting: configtls.TLSClientSetting{
+					TLSSetting: configtls.TLSSetting{
+						CAFile: "/var/lib/mycert.pem", //This is subject to change, but currently I have no idea what else to put here lol
+					},
+					Insecure: false,
+				},
+				ReadBufferSize: 0,
+
+				WriteBufferSize: 512 * 1024,
+
+				Timeout: 5 * time.Second,
+			},
+		})
+}