[connector/count] Add outline and documentation

.github/CODEOWNERS

@@ -29,6 +29,8 @@ cmd/tracegen/                                            @open-telemetry/collect
 
 confmap/provider/s3provider/                             @open-telemetry/collector-contrib-approvers @Aneurysm9
 
+connector/countconnector/                                @open-telemetry/collector-contrib-approvers @djaglowski @jpkrohling
+
 examples/demo/                                           @open-telemetry/collector-contrib-approvers @open-telemetry/collector-approvers
 
 exporter/alibabacloudlogserviceexporter/                 @open-telemetry/collector-contrib-approvers @shabicheng @kongluoxing @qiansheng91

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -25,6 +25,7 @@ body:
       - cmd/telemetrygen
       - cmd/tracegen
       - confmap/provider/s3provider
+      - connector/count
       - examples/demo
       - exporter/alibabacloudlogservice
       - exporter/awscloudwatchlogs
@@ -228,7 +229,7 @@ body:
       description: Please provide as much detail as you reasonably can.
       value: |
         ## Description
-      
+
         ## Steps to Reproduce
 
         ## Expected Result

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -19,6 +19,7 @@ body:
       - cmd/telemetrygen
       - cmd/tracegen
       - confmap/provider/s3provider
+      - connector/count
       - examples/demo
       - exporter/alibabacloudlogservice
       - exporter/awscloudwatchlogs

.github/ISSUE_TEMPLATE/other.yaml

@@ -19,6 +19,7 @@ body:
       - cmd/telemetrygen
       - cmd/tracegen
       - confmap/provider/s3provider
+      - connector/count
       - examples/demo
       - exporter/alibabacloudlogservice
       - exporter/awscloudwatchlogs

.github/dependabot.yml

@@ -42,6 +42,10 @@ updates:
     directory: "/confmap/provider/s3provider"
     schedule:
       interval: "weekly"
+  - package-ecosystem: "gomod"
+    directory: "/connector/count"
+    schedule:
+      interval: "weekly"
   - package-ecosystem: "gomod"
     directory: "/examples/demo/client"
     schedule:

connector/countconnector/Makefile

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

connector/countconnector/README.md

@@ -0,0 +1,213 @@
+# Count Connector
+
+| Status                   |                                                           |
+|------------------------- |---------------------------------------------------------- |
+| Stability                | [in development]                                          |
+| Supported pipeline types | See [Supported Pipeline Types](#supported-pipeline-types) |
+| Distributions            | []                                                        |
+
+The `countconnector` can be used to count spans, data points, or log records.
+
+## Supported Pipeline Types
+
+Connectors are used as _both_ an exporter and as a receiver, in separate pipelines.
+The pipeline in which a connector is used as an exporter is referred to below
+as the "Exporter pipeline". Likewise, the pipeline in which the connector is
+used as a receiver is referred to below as the "Receiver pipeline".
+
+| Exporter pipeline | Receiver pipeline | Description                        | Default Metric Name       |
+| ----------------- | ----------------- | ---------------------------------- | ------------------------- |
+| traces            | metrics           | Counts the number of spans.        | `trace.span.count`        |
+| metrics           | metrics           | Counts the number of log records.  | `metric.data_point.count` |
+| logs              | metrics           | Counts the number of data points.  | `log.record.count`        |
+
+## Configuration
+
+Connectors are defined within a dedicated `connectors` section at the top level of the collector config.
+
+The count connector may be used with default settings.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar:
+connectors:
+  count:
+```
+
+Optionally, the names of the metrics emitted by the connector may be customized.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar:
+connectors:
+  count:
+    traces:
+      metric_name: my.span.count
+    metrics:
+      metric_name: my.data_point.count
+    logs:
+      metric_name: my.log_record.count
+```
+
+### Use the connector in pipelines
+
+A connector _is_ an exporter _and_ a receiver. It must be used as both, in separate pipelines.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo]
+      exporters: [count]
+    metrics:
+      receivers: [count]
+      exporters: [bar]
+```
+
+Connectors can be used alongside other exporters.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar/traces_backend:
+  bar/metrics_backend:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo]
+      exporters: [bar/traces_backend, count]
+    metrics:
+      receivers: [count]
+      exporters: [bar/metrics_backend]
+```
+
+Connectors can be used alongside other receivers.
+
+```yaml
+receivers:
+  foo/traces:
+  foo/metrics:
+exporters:
+  bar:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo/traces]
+      exporters: [count]
+    metrics:
+      receivers: [foo/metrics, count]
+      exporters: [bar]
+```
+
+A connector can be an exporter from multiple pipelines.
+
+```yaml
+receivers:
+  foo/traces:
+  foo/metrics:
+  foo/logs:
+exporters:
+  bar/traces_backend:
+  bar/metrics_backend:
+  bar/logs_backend:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo/traces]
+      exporters: [bar/traces_backend, count]
+    metrics:
+      receivers: [foo/metrics]
+      exporters: [bar/metrics_backend, count]
+    logs:
+      receivers: [foo/logs]
+      exporters: [bar/logs_backend, count]
+    metrics/counts:
+      receivers: [count]
+      exporters: [bar/metrics_backend]
+```
+
+A connector can be a receiver in multiple pipelines.
+
+```yaml
+receivers:
+  foo/traces:
+  foo/metrics:
+exporters:
+  bar/traces_backend:
+  bar/metrics_backend:
+  bar/metrics_backend/2:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo/traces]
+      exporters: [bar/traces_backend, count]
+    metrics:
+      receivers: [count]
+      exporters: [bar/metrics_backend]
+    metrics/2:
+      receivers: [count]
+      exporters: [bar/metrics_backend/2]
+```
+
+Multiple connectors can be used in sequence.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar:
+connectors:
+  count:
+  count/the_counts:
+service:
+  pipelines:
+    traces:
+      receivers: [foo]
+      exporters: [count]
+    metrics:
+      receivers: [count]
+      exporters: [bar/metrics_backend, count/the_counts]
+    metrics/count_the_counts:
+      receivers: [count/the_counts]
+      exporters: [bar]
+```
+
+A connector can only be used in a pair of pipelines when it supports the combination of _exporter type_ and _receiver type_.
+
+```yaml
+receivers:
+  foo:
+exporters:
+  bar:
+connectors:
+  count:
+service:
+  pipelines:
+    traces:
+      receivers: [foo]
+      exporters: [count]
+    logs:
+      receivers: [count] # Invalid. The count connector can only be used as a receiver in metrics pipelines.
+      exporters: [bar]
+```
+
+[in development]:https://github.com/open-telemetry/opentelemetry-collector#in-development

connector/countconnector/config.go

@@ -0,0 +1,19 @@
+// 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 countconnector // import "github.com/open-telemetry/opentelemetry-collector-contrib/connector/countconnector"
+
+type Config struct {
+	// TODO
+}

connector/countconnector/doc.go

@@ -0,0 +1,15 @@
+// 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 countconnector // import "github.com/open-telemetry/opentelemetry-collector-contrib/connector/countconnector"

connector/countconnector/factory.go

@@ -0,0 +1,75 @@
+// 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 countconnector // import "github.com/open-telemetry/opentelemetry-collector-contrib/connector/countconnector"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/connector"
+	"go.opentelemetry.io/collector/consumer"
+)
+
+const (
+	typeStr   = "count"
+	stability = component.StabilityLevelDevelopment
+	scopeName = "otelcol/countconnector"
+)
+
+// NewFactory returns a ConnectorFactory.
+func NewFactory() connector.Factory {
+	return connector.NewFactory(
+		typeStr,
+		createDefaultConfig,
+		connector.WithTracesToMetrics(createTracesToMetrics, component.StabilityLevelDevelopment),
+		connector.WithMetricsToMetrics(createMetricsToMetrics, component.StabilityLevelDevelopment),
+		connector.WithLogsToMetrics(createLogsToMetrics, component.StabilityLevelDevelopment),
+	)
+}
+
+// createDefaultConfig creates the default configuration.
+func createDefaultConfig() component.Config {
+	return &Config{}
+}
+
+// createTracesToMetrics creates a traces to metrics connector based on provided config.
+func createTracesToMetrics(
+	_ context.Context,
+	set connector.CreateSettings,
+	cfg component.Config,
+	nextConsumer consumer.Metrics,
+) (connector.Traces, error) {
+	return nil, nil
+}
+
+// createMetricsToMetrics creates a metrics connector based on provided config.
+func createMetricsToMetrics(
+	_ context.Context,
+	set connector.CreateSettings,
+	cfg component.Config,
+	nextConsumer consumer.Metrics,
+) (connector.Metrics, error) {
+	return nil, nil
+}
+
+// createLogsToMetrics creates a logs to metrics connector based on provided config.
+func createLogsToMetrics(
+	_ context.Context,
+	set connector.CreateSettings,
+	cfg component.Config,
+	nextConsumer consumer.Metrics,
+) (connector.Logs, error) {
+	return nil, nil
+}