Add DataDog exporter back from old fork

commit 99129fb96e29e9c1a92da00b7e3f8efcae8a31e8
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Thu Sep 3 18:10:28 2020 +0200

    Handle namespace at initialization time

commit babca25927926a60c0c416294af3aadf784d41b9
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Thu Sep 3 17:23:53 2020 +0200

    Initialize on a separate function
    This way the variables can be checked without worrying about the env

commit 24d0cb4cc566fa5313a8650c904a27bea68bf555
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Thu Sep 3 14:30:35 2020 +0200

    Check environment variables for unified service tagging

commit 6695f8297ab8b1fcae71b05acb027c4a0992e3a0
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Wed Sep 2 14:57:37 2020 +0200

    Add support for sending metrics through the API
    - Use datadog.Metric type for simplicity
    - Get host if unset

commit c366603
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Wed Sep 2 09:56:24 2020 +0200

    Disable Queue and Retry settings (#72)

    These are handled by the statsd package.
    OpenTelemetry docs are confusing and the default configuration (disabled)
    is different from the one returned by "GetDefault..." functions

commit a660b56
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Tue Sep 1 15:26:14 2020 +0200

    Add support for summary and distribution metric types (#65)

    * Add support for summary metric type

    * Add support for distribution metrics

    * Refactor metrics construction
    - Drop name in Metrics (now they act as Metric values)
    - Refactor constructor so that errors happen at compile-time

    * Report Summary total sum and count values
    Snapshot values are not filled in by OpenTelemetry

    * Report p00 and p100 as `.min` and `.max`
    This is more similar to what we do for our own non-additive type

    * Keep hostname if it has not been overridden

commit c95adc4
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Thu Aug 27 13:00:02 2020 +0200

    Update dependencies and `make gofmt`
    The collector was updated to 0.9.0 upstream

commit 20afb0e
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Wed Aug 26 18:25:49 2020 +0200

    Refactor configuration (#45)

    * Refactor configuration
    * Implement telemetry and tags configuration handling
    * Update example configuration and README file
    Co-authored-by: Kylian Serrania <kylian.serrania@datadoghq.com>

commit fdc98b5
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Fri Aug 21 11:09:08 2020 +0200

    Initial DogStatsD implementation (#15)

    Initial metrics exporter through DogStatsD with support for all metric types but summary and distribution

commit e848a60
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Fri Aug 21 10:42:45 2020 +0200

    Bump collector version

commit 58be9a4
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Thu Aug 6 10:04:32 2020 +0200

    Address linter

commit 695430c
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Tue Aug 4 13:28:01 2020 +0200

    Fix field name error

    MetricsEndpoint was renamed to MetricsURL

commit 168b319
Author: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date:   Mon Aug 3 11:05:01 2020 +0200

    Create initial outline for Datadog exporter (#1)

    * Add support for basic configuration options
    * Documents configuration options

cmd/otelcontribcol/components.go

@@ -23,6 +23,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/awsxrayexporter"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/azuremonitorexporter"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/carbonexporter"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/datadogexporter"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticexporter"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/honeycombexporter"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/jaegerthrifthttpexporter"
@@ -115,6 +116,7 @@ func components() (component.Factories, error) {
 		elasticexporter.NewFactory(),
 		alibabacloudlogserviceexporter.NewFactory(),
 		sentryexporter.NewFactory(),
+		datadogexporter.NewFactory(),
 	}
 	for _, exp := range factories.Exporters {
 		exporters = append(exporters, exp)

exporter/datadogexporter/Makefile

@@ -0,0 +1 @@
+include ../../Makefile.Common

exporter/datadogexporter/README.md

@@ -0,0 +1,22 @@
+# Datadog Exporter
+
+This exporter sends metric data to [Datadog](https://datadoghq.com).
+
+## Configuration
+
+The metrics exporter has two modes:
+  - If sending metrics through DogStatsD (the default mode), there are no required settings. 
+  - If sending metrics without an Agent the mode must be set explicitly and
+      you must provide a [Datadog API key](https://app.datadoghq.com/account/settings#api).
+ ```yaml
+datadog:
+  api:
+    key: "<API key>"
+    # site: datadoghq.eu for sending data to the Datadog EU site
+   metrics:
+     mode: agentless
+ ```
+
+The hostname, environment, service and version can be set in the configuration for unified service tagging.
+
+See the sample configuration file under the `example` folder for other available options.

exporter/datadogexporter/config.go

@@ -0,0 +1,211 @@
+// 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 datadogexporter
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"go.opentelemetry.io/collector/config/configmodels"
+)
+
+var (
+	errUnsetAPIKey = errors.New("the Datadog API key is unset")
+)
+
+const (
+	NoneMode      = "none"
+	AgentlessMode = "agentless"
+	DogStatsDMode = "dogstatsd"
+)
+
+// APIConfig defines the API configuration options
+type APIConfig struct {
+	// Key is the Datadog API key to associate your Agent's data with your organization.
+	// Create a new API key here: https://app.datadoghq.com/account/settings
+	Key string `mapstructure:"key"`
+
+	// Site is the site of the Datadog intake to send data to.
+	// The default value is "datadoghq.com".
+	Site string `mapstructure:"site"`
+}
+
+// GetCensoredKey returns the API key censored for logging purposes
+func (api *APIConfig) GetCensoredKey() string {
+	if len(api.Key) <= 5 {
+		return api.Key
+	}
+	return strings.Repeat("*", len(api.Key)-5) + api.Key[:len(api.Key)-5]
+}
+
+// DogStatsDConfig defines the DogStatsd related configuration
+type DogStatsDConfig struct {
+	// Endpoint is the DogStatsD address.
+	// The default value is 127.0.0.1:8125
+	// A Unix address is supported
+	Endpoint string `mapstructure:"endpoint"`
+
+	// Telemetry states whether to send metrics
+	Telemetry bool `mapstructure:"telemetry"`
+}
+
+// AgentlessConfig defines the Agentless related configuration
+type AgentlessConfig struct {
+	// Endpoint is the host of the Datadog intake server to send metrics to.
+	// If unset, the value is obtained from the Site.
+	Endpoint string `mapstructure:"endpoint"`
+}
+
+// MetricsConfig defines the metrics exporter specific configuration options
+type MetricsConfig struct {
+	// Namespace is the namespace under which the metrics are sent
+	// By default metrics are not namespaced
+	Namespace string `mapstructure:"namespace"`
+
+	// Mode is the metrics sending mode: either 'dogstatsd' or 'agentless'
+	Mode string `mapstructure:"mode"`
+
+	// Percentiles states whether to report percentiles for summary metrics,
+	// including the minimum and maximum
+	Percentiles bool `mapstructure:"report_percentiles"`
+
+	// Buckets states whether to report buckets from distribution metrics
+	Buckets bool `mapstructure:"report_buckets"`
+
+	// DogStatsD defines the DogStatsD configuration options.
+	DogStatsD DogStatsDConfig `mapstructure:"dogstatsd"`
+
+	// Agentless defines the Agentless configuration options.
+	Agentless AgentlessConfig `mapstructure:"agentless"`
+}
+
+// TagsConfig defines the tag-related configuration
+// It is embedded in the configuration
+type TagsConfig struct {
+	// Hostname is the host name for unified service tagging.
+	// If unset, it is determined automatically.
+	// See https://docs.datadoghq.com/agent/faq/how-datadog-agent-determines-the-hostname
+	// for more details.
+	Hostname string `mapstructure:"hostname"`
+
+	// Env is the environment for unified service tagging.
+	// It can also be set through the `DD_ENV` environment variable.
+	Env string `mapstructure:"env"`
+
+	// Service is the service for unified service tagging.
+	// It can also be set through the `DD_SERVICE` environment variable.
+	Service string `mapstructure:"service"`
+
+	// Version is the version for unified service tagging.
+	// It can also be set through the `DD_VERSION` version variable.
+	Version string `mapstructure:"version"`
+
+	// Tags is the list of default tags to add to every metric or trace.
+	Tags []string `mapstructure:"tags"`
+}
+
+// UpdateWithEnv gets the unified service tagging information
+// from the environment variables.
+func (t *TagsConfig) UpdateWithEnv() {
+	if t.Hostname == "" {
+		t.Hostname = os.Getenv("DD_HOST")
+	}
+
+	if t.Env == "" {
+		t.Env = os.Getenv("DD_ENV")
+	}
+
+	if t.Service == "" {
+		t.Service = os.Getenv("DD_SERVICE")
+	}
+
+	if t.Version == "" {
+		t.Version = os.Getenv("DD_VERSION")
+	}
+}
+
+// GetTags gets the default tags extracted from the configuration
+func (t *TagsConfig) GetTags(addHost bool) []string {
+	tags := make([]string, 0, 4)
+
+	vars := map[string]string{
+		"env":     t.Env,
+		"service": t.Service,
+		"version": t.Version,
+	}
+
+	if addHost {
+		vars["host"] = t.Hostname
+	}
+
+	for name, val := range vars {
+		if val != "" {
+			tags = append(tags, fmt.Sprintf("%s:%s", name, val))
+		}
+	}
+
+	tags = append(tags, t.Tags...)
+
+	return tags
+}
+
+// Config defines configuration for the Datadog exporter.
+type Config struct {
+	configmodels.ExporterSettings `mapstructure:",squash"` // squash ensures fields are correctly decoded in embedded struct.
+
+	TagsConfig `mapstructure:",squash"`
+
+	// API defines the Datadog API configuration.
+	API APIConfig `mapstructure:"api"`
+
+	// Metrics defines the Metrics exporter specific configuration
+	Metrics MetricsConfig `mapstructure:"metrics"`
+}
+
+// Sanitize tries to sanitize a given configuration
+func (c *Config) Sanitize() error {
+
+	if c.Metrics.Mode != AgentlessMode && c.Metrics.Mode != DogStatsDMode {
+		return fmt.Errorf("Metrics mode '%s' is not recognized", c.Metrics.Mode)
+	}
+
+	// Get info from environment variables
+	// if unset
+	c.TagsConfig.UpdateWithEnv()
+
+	// Add '.' at the end of namespace
+	// to have the same behavior on DogStatsD and the API
+	if c.Metrics.Namespace != "" && !strings.HasSuffix(c.Metrics.Namespace, ".") {
+		c.Metrics.Namespace = c.Metrics.Namespace + "."
+	}
+
+	// Exactly one configuration for metrics must be set
+	if c.Metrics.Mode == AgentlessMode {
+		if c.API.Key == "" {
+			return errUnsetAPIKey
+		}
+
+		c.API.Key = strings.TrimSpace(c.API.Key)
+
+		// Set the endpoint based on the Site
+		if c.Metrics.Agentless.Endpoint == "" {
+			c.Metrics.Agentless.Endpoint = fmt.Sprintf("https://api.%s", c.API.Site)
+		}
+	}
+
+	return nil
+}

exporter/datadogexporter/config_test.go

@@ -0,0 +1,131 @@
+// 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 datadogexporter
+
+import (
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/component/componenttest"
+	"go.opentelemetry.io/collector/config/configmodels"
+	"go.opentelemetry.io/collector/config/configtest"
+)
+
+// TestLoadConfig tests that the configuration is 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)
+
+	apiConfig := cfg.Exporters["datadog/api"].(*Config)
+	err = apiConfig.Sanitize()
+
+	require.NoError(t, err)
+	assert.Equal(t, apiConfig, &Config{
+		ExporterSettings: configmodels.ExporterSettings{
+			NameVal: "datadog/api",
+			TypeVal: "datadog",
+		},
+
+		TagsConfig: TagsConfig{
+			Hostname: "customhostname",
+			Env:      "prod",
+			Service:  "myservice",
+			Version:  "myversion",
+			Tags:     []string{"example:tag"},
+		},
+
+		API: APIConfig{
+			Key:  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+			Site: "datadoghq.eu",
+		},
+
+		Metrics: MetricsConfig{
+			Mode:        AgentlessMode,
+			Namespace:   "opentelemetry.",
+			Percentiles: false,
+
+			DogStatsD: DogStatsDConfig{
+				Endpoint:  "127.0.0.1:8125",
+				Telemetry: true,
+			},
+
+			Agentless: AgentlessConfig{
+				Endpoint: "https://api.datadoghq.eu",
+			},
+		},
+	})
+
+	dogstatsdConfig := cfg.Exporters["datadog/dogstatsd"].(*Config)
+	err = dogstatsdConfig.Sanitize()
+
+	require.NoError(t, err)
+	assert.Equal(t, dogstatsdConfig, &Config{
+		ExporterSettings: configmodels.ExporterSettings{
+			NameVal: "datadog/dogstatsd",
+			TypeVal: "datadog",
+		},
+
+		TagsConfig: TagsConfig{},
+		API:        APIConfig{Site: "datadoghq.com"},
+
+		Metrics: MetricsConfig{
+			Mode:        DogStatsDMode,
+			Percentiles: true,
+			DogStatsD: DogStatsDConfig{
+				Endpoint:  "127.0.0.1:8125",
+				Telemetry: true,
+			},
+
+			Agentless: AgentlessConfig{},
+		},
+	})
+
+	invalidConfig := cfg.Exporters["datadog/invalid"].(*Config)
+	err = invalidConfig.Sanitize()
+	require.Error(t, err)
+
+	invalidConfig2 := cfg.Exporters["datadog/agentless/invalid"].(*Config)
+	err = invalidConfig2.Sanitize()
+	require.Error(t, err)
+
+}
+
+// TestOverrideMetricsURL tests that the metrics URL is overridden
+// correctly when set manually.
+func TestOverrideMetricsURL(t *testing.T) {
+
+	const DebugEndpoint string = "http://localhost:8080"
+
+	cfg := Config{
+		API: APIConfig{Key: "notnull", Site: DefaultSite},
+		Metrics: MetricsConfig{
+			Mode:      AgentlessMode,
+			Agentless: AgentlessConfig{Endpoint: DebugEndpoint},
+		},
+	}
+
+	err := cfg.Sanitize()
+	require.NoError(t, err)
+	assert.Equal(t, cfg.Metrics.Agentless.Endpoint, DebugEndpoint)
+}