otelcol.receiver.zipkin: new component (#2685)

This commit adds otelcol.receiver.zipkin as a new Flow component,
wrapping around the upstream zipkin receiver from the OpenTelemetry
Collector otelcol-contrib distribution.

otelcol.receiver.zipkin spawns an HTTP server which can read
Zipkin-formatted traces over the network.

Closes #2293.

CHANGELOG.md

@@ -35,6 +35,8 @@ Main (unreleased)
   - `phlare.scrape` collects application performance profiles. (@cyriltovena)
   - `phlare.write` sends application performance profiles to Grafana Phlare. (@cyriltovena)
 
+  - `otelcol.receiver.zipkin` receives Zipkin-formatted traces. (@rfratto)
+
 ### Enhancements
 
 - Handle faro-web-sdk `View` meta in app_agent_receiver. (@rlankfo)

component/all/all.go

@@ -24,6 +24,7 @@ import (
 	_ "github.com/grafana/agent/component/otelcol/receiver/kafka"               // Import otelcol.receiver.kafka
 	_ "github.com/grafana/agent/component/otelcol/receiver/otlp"                // Import otelcol.receiver.otlp
 	_ "github.com/grafana/agent/component/otelcol/receiver/prometheus"          // Import otelcol.receiver.prometheus
+	_ "github.com/grafana/agent/component/otelcol/receiver/zipkin"              // Import otelcol.receiver.zipkin
 	_ "github.com/grafana/agent/component/phlare/scrape"                        // Import phlare.scrape
 	_ "github.com/grafana/agent/component/phlare/write"                         // Import phlare.write
 	_ "github.com/grafana/agent/component/prometheus/integration/node_exporter" // Import prometheus.integration.node_exporter

component/otelcol/receiver/kafka/kafka.go

@@ -89,6 +89,8 @@ func (args *Arguments) UnmarshalRiver(f func(interface{}) error) error {
 // Convert implements receiver.Arguments.
 func (args Arguments) Convert() otelconfig.Receiver {
 	return &kafkareceiver.Config{
+		ReceiverSettings: otelconfig.NewReceiverSettings(otelconfig.NewComponentID("kafka")),
+
 		Brokers:         args.Brokers,
 		ProtocolVersion: args.ProtocolVersion,
 		Topic:           args.Topic,

component/otelcol/receiver/zipkin/zipkin.go

@@ -0,0 +1,79 @@
+// Package zipkin provides an otelcol.receiver.zipkin component.
+package zipkin
+
+import (
+	"github.com/grafana/agent/component"
+	"github.com/grafana/agent/component/otelcol"
+	"github.com/grafana/agent/component/otelcol/receiver"
+	"github.com/grafana/agent/pkg/river"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/zipkinreceiver"
+	otelcomponent "go.opentelemetry.io/collector/component"
+	otelconfig "go.opentelemetry.io/collector/config"
+)
+
+func init() {
+	component.Register(component.Registration{
+		Name: "otelcol.receiver.zipkin",
+		Args: Arguments{},
+
+		Build: func(opts component.Options, args component.Arguments) (component.Component, error) {
+			fact := zipkinreceiver.NewFactory()
+			return receiver.New(opts, fact, args.(Arguments))
+		},
+	})
+}
+
+// Arguments configures the otelcol.receiver.zipkin component.
+type Arguments struct {
+	ParseStringTags bool `river:"parse_string_tags,attr,optional"`
+
+	HTTPServer otelcol.HTTPServerArguments `river:"http,block,optional"`
+
+	// Output configures where to send received data. Required.
+	Output *otelcol.ConsumerArguments `river:"output,block"`
+}
+
+var (
+	_ receiver.Arguments = Arguments{}
+	_ river.Unmarshaler  = (*Arguments)(nil)
+)
+
+// DefaultArguments holds default settings for otelcol.receiver.zipkin.
+var DefaultArguments = Arguments{
+	HTTPServer: otelcol.HTTPServerArguments{
+		Endpoint: "0.0.0.0:9411",
+	},
+}
+
+// UnmarshalRiver applies defaults to args before unmarshaling.
+func (args *Arguments) UnmarshalRiver(f func(interface{}) error) error {
+	*args = DefaultArguments
+
+	type arguments Arguments
+	return f((*arguments)(args))
+}
+
+// Convert implements receiver.Arguments.
+func (args Arguments) Convert() otelconfig.Receiver {
+	return &zipkinreceiver.Config{
+		ReceiverSettings: otelconfig.NewReceiverSettings(otelconfig.NewComponentID("zipkin")),
+
+		ParseStringTags:    args.ParseStringTags,
+		HTTPServerSettings: *args.HTTPServer.Convert(),
+	}
+}
+
+// Extensions implements receiver.Arguments.
+func (args Arguments) Extensions() map[otelconfig.ComponentID]otelcomponent.Extension {
+	return nil
+}
+
+// Exporters implements receiver.Arguments.
+func (args Arguments) Exporters() map[otelconfig.DataType]map[otelconfig.ComponentID]otelcomponent.Exporter {
+	return nil
+}
+
+// NextConsumers implements receiver.Arguments.
+func (args Arguments) NextConsumers() *otelcol.ConsumerArguments {
+	return args.Output
+}

docs/sources/flow/reference/components/otelcol.receiver.otlp.md

@@ -160,15 +160,15 @@ Name | Type | Description | Default | Required
 `allowed_headers` | `list(string)` | Accepted headers from CORS requests. | `["X-Requested-With"]` | no
 `max_age` | `number` | Configures the `Access-Control-Max-Age` response header. | | no
 
-The `allowed_headers` specifies which headers are acceptable from a CORS
-request. The following headers are always implicitly allowed:
+The `allowed_headers` argument specifies which headers are acceptable from a
+CORS request. The following headers are always implicitly allowed:
 
 * `Accept`
 * `Accept-Language`
 * `Content-Type`
 * `Content-Language`
 
-If `allowed_headers` includes `"*"`, all headers will be permitted.
+If `allowed_headers` includes `"*"`, all headers are permitted.
 
 ### output block
 

docs/sources/flow/reference/components/otelcol.receiver.zipkin.md

@@ -0,0 +1,155 @@
+---
+aliases:
+- /docs/agent/latest/flow/reference/components/otelcol.receiver.zipkin
+title: otelcol.receiver.zipkin
+---
+
+# otelcol.receiver.zipkin
+
+`otelcol.receiver.zipkin` accepts Zipkin-formatted traces over the network and
+forwards it to other `otelcol.*` components.
+
+> **NOTE**: `otelcol.receiver.zipkin` is a wrapper over the upstream
+> OpenTelemetry Collector `zipkin` receiver. Bug reports or feature requests
+> will be redirected to the upstream repository, if necessary.
+
+Multiple `otelcol.receiver.zipkin` components can be specified by giving them
+different labels.
+
+## Usage
+
+```river
+otelcol.receiver.zipkin "LABEL" {
+  output {
+    traces = [...]
+  }
+}
+```
+
+## Arguments
+
+`otelcol.receiver.zipkin` supports the following arguments:
+
+Name | Type | Description | Default | Required
+---- | ---- | ----------- | ------- | --------
+`parse_string_tags` | `bool` | Parse string tags and binary annotations into non-string types. | `false` | no
+
+If `parse_string_tags` is `true`, string tags and binary annotations are
+converted to `int`, `bool`, and `float` if possible. String tags and binary
+annotations that cannot be converted remain unchanged.
+
+## Blocks
+
+The following blocks are supported inside the definition of
+`otelcol.receiver.zipkin`:
+
+Hierarchy | Block | Description | Required
+--------- | ----- | ----------- | --------
+http | [http][] | Configures the HTTP server to receive telemetry data. | no
+http > tls | [tls][] | Configures TLS for the HTTP server. | no
+http > cors | [cors][] | Configures CORS for the HTTP server. | no
+output | [output][] | Configures where to send received traces. | yes
+
+The `>` symbol indicates deeper levels of nesting. For example, `grpc > tls`
+refers to a `tls` block defined inside a `grpc` block.
+
+[http]: #http-block
+[tls]: #tls-block
+[cors]: #cors-block
+[output]: #output-block
+
+### http block
+
+The `http` block configures the HTTP server used by the component.
+
+The following arguments are supported:
+
+Name | Type | Description | Default | Required
+---- | ---- | ----------- | ------- | --------
+`endpoint` | `string` | `host:port` to listen for traffic on. | `"0.0.0.0:9411"` | no
+`max_request_body_size` | `string` | Maximum request body size the server will allow. No limit when unset. | | no
+`include_metadata` | `boolean` | Propagate incoming connection metadata to downstream consumers. | | no
+
+### tls block
+
+The `tls` block configures TLS settings used for a server. If the `tls` block
+isn't provided, TLS won't be used for connections to the server.
+
+The following arguments are supported:
+
+Name | Type | Description | Default | Required
+---- | ---- | ----------- | ------- | --------
+`ca_file` | `string` | Path to the CA file. | | no
+`cert_file` | `string` | Path to the TLS certificate. | | no
+`key_file` | `string` | Path to the TLS certificate key. | | no
+`min_version` | `string` | Minimum acceptable TLS version for connections. | `"TLS 1.2"` | no
+`max_version` | `string` | Maximum acceptable TLS version for connections. | `"TLS 1.3"` | no
+`reload_interval` | `duration` | Frequency to reload the certificates. | | no
+`client_ca_file` | `string` | Path to the CA file used to authenticate client certificates. | | no
+
+### cors block
+
+The `cors` block configures CORS settings for an HTTP server.
+
+The following arguments are supported:
+
+Name | Type | Description | Default | Required
+---- | ---- | ----------- | ------- | --------
+`allowed_origins` | `list(string)` | Allowed values for the `Origin` header. | | no
+`allowed_headers` | `list(string)` | Accepted headers from CORS requests. | `["X-Requested-With"]` | no
+`max_age` | `number` | Configures the `Access-Control-Max-Age` response header. | | no
+
+The `allowed_headers` argument specifies which headers are acceptable from a
+CORS request. The following headers are always implicitly allowed:
+
+* `Accept`
+* `Accept-Language`
+* `Content-Type`
+* `Content-Language`
+
+If `allowed_headers` includes `"*"`, all headers are permitted.
+
+### output block
+
+{{< docs/shared lookup="flow/reference/components/output-block.md" source="agent" >}}
+
+## Exported fields
+
+`otelcol.receiver.zipkin` does not export any fields.
+
+## Component health
+
+`otelcol.receiver.zipkin` is only reported as unhealthy if given an invalid
+configuration.
+
+## Debug information
+
+`otelcol.receiver.zipkin` does not expose any component-specific debug
+information.
+
+## Example
+
+This example forwards received traces through a batch processor before finally
+sending it to an OTLP-capable endpoint:
+
+```river
+otelcol.receiver.zipkin "default" {
+  output {
+    traces = [otelcol.processor.batch.default.input]
+  }
+}
+
+otelcol.processor.batch "default" {
+  output {
+    metrics = [otelcol.exporter.otlp.default.input]
+    logs    = [otelcol.exporter.otlp.default.input]
+    traces  = [otelcol.exporter.otlp.default.input]
+  }
+}
+
+otelcol.exporter.otlp "default" {
+  client {
+    endpoint = env("OTLP_ENDPOINT")
+  }
+}
+```