add config parsing module

This module parses configuration as defined per the opentelemetry-configuration schema.

Signed-off-by: Alex Boten <aboten@lightstep.com>

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Set the description for the `rpc.server.duration` metric in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#4302)
 - Add `NewServerHandler` and `NewClientHandler` that return a `grpc.StatsHandler` used for gRPC instrumentation in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#3002)
 - Add new Prometheus bridge module in `go.opentelemetry.io/contrib/bridges/prometheus`. (#4227)
+- Add module to parse configuration as per opentelemetry-config schema. (#4228)
 
 ### Changed
 

Makefile

@@ -74,6 +74,9 @@ $(GOTMPL): PACKAGE=go.opentelemetry.io/build-tools/gotmpl
 GORELEASE = $(TOOLS)/gorelease
 $(GORELEASE): PACKAGE=golang.org/x/exp/cmd/gorelease
 
+GOJSONSCHEMA = $(TOOLS)/go-jsonschema
+$(GOJSONSCHEMA): PACKAGE=github.com/atombender/go-jsonschema/cmd/gojsonschema
+
 tools: $(GOLANGCI_LINT) $(MISSPELL) $(GOCOVMERGE) $(STRINGER) $(PORTO) $(MULTIMOD) $(DBOTCONF) $(CROSSLINK) $(GOTMPL) $(GORELEASE)
 
 # Generate
@@ -283,3 +286,31 @@ COMMIT ?= "HEAD"
 add-tags: | $(MULTIMOD)
 	@[ "${MODSET}" ] || ( echo ">> env var MODSET is not set"; exit 1 )
 	$(MULTIMOD) verify && $(MULTIMOD) tag -m ${MODSET} -c ${COMMIT}
+
+# The source directory for opentelemetry-configuration schema.
+OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_SRC_DIR=tmp/opentelememetry-configuration
+
+# The SHA matching the current version of the opentelemetry-configuration schema to use
+OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_VERSION=main
+
+# Cleanup temporary directory
+genjsonschema-cleanup:
+	rm -Rf ${OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_SRC_DIR}
+
+GENERATED_CONFIG=./config/generated_config.go
+
+# Generate structs for configuration from opentelemetry-configuration schema
+genjsonschema: genjsonschema-cleanup $(GOJSONSCHEMA)
+	mkdir -p ${OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_SRC_DIR}
+	curl -sSL https://api.github.com/repos/open-telemetry/opentelemetry-configuration/tarball/${OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_VERSION} | tar xz --strip 1 -C ${OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_SRC_DIR}
+	$(GOJSONSCHEMA) \
+		--package config \
+		--tags mapstructure \
+		--output ${GENERATED_CONFIG} \
+		--schema-package=https://opentelemetry.io/otelconfig/opentelemetry_configuration.json=github.com/open-telemetry/opentelemetry-collector/schema \
+    	${OPENTELEMETRY_CONFIGURATION_JSONSCHEMA_SRC_DIR}/schema/opentelemetry_configuration.json
+	@echo Modify jsonschema generated files.
+	sed -f ./config/jsonschema_patch.sed ${GENERATED_CONFIG} > ${GENERATED_CONFIG}.tmp
+	mv ${GENERATED_CONFIG}.tmp ${GENERATED_CONFIG}
+	$(MAKE) lint
+	$(MAKE) genjsonschema-cleanup

config/config.go

@@ -0,0 +1,123 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package config // import "go.opentelemetry.io/contrib/config"
+
+import (
+	"fmt"
+)
+
+// Validate checks for a valid batch processor for the SpanProcessor.
+func (sp *SpanProcessor) Validate() error {
+	if sp.Batch != nil {
+		return sp.Batch.Exporter.Validate()
+	}
+	return fmt.Errorf("unsupported span processor type")
+}
+
+// Validate checks for valid exporters to be configured for the SpanExporter.
+func (se *SpanExporter) Validate() error {
+	if se.Console == nil && se.Otlp == nil {
+		return fmt.Errorf("invalid exporter configuration")
+	}
+	return nil
+}
+
+// Validate checks for either a valid pull or periodic exporter for the MetricReader.
+func (mr *MetricReader) Validate() error {
+	if mr.Pull != nil {
+		return mr.Pull.Validate()
+	}
+	if mr.Periodic != nil {
+		return mr.Periodic.Validate()
+	}
+
+	return fmt.Errorf("unsupported metric reader type")
+}
+
+// Validate checks for valid exporters to be configured for the PullMetricReader.
+func (pmr *PullMetricReader) Validate() error {
+	if pmr.Exporter.Prometheus == nil {
+		return fmt.Errorf("invalid exporter configuration")
+	}
+	return nil
+}
+
+// Validate checks for valid exporters to be configured for the PeriodicMetricReader.
+func (pmr *PeriodicMetricReader) Validate() error {
+	if pmr.Exporter.Otlp == nil && pmr.Exporter.Console == nil {
+		return fmt.Errorf("invalid exporter configuration")
+	}
+	return nil
+}
+
+// Validate checks for a valid Selector or Stream to be configured for the View.
+func (v *View) Validate() error {
+	if v.Selector == nil || v.Stream == nil {
+		return fmt.Errorf("invalid view configuration")
+	}
+	return nil
+}
+
+func (s *ViewSelector) instrumentNameStr() string {
+	if s.InstrumentName == nil {
+		return ""
+	}
+	return *s.InstrumentName
+}
+
+func (s *ViewSelector) instrumentTypeStr() string {
+	if s.InstrumentType == nil {
+		return ""
+	}
+	return string(*s.InstrumentType)
+}
+
+func (s *ViewSelector) meterNameStr() string {
+	if s.MeterName == nil {
+		return ""
+	}
+	return *s.MeterName
+}
+
+func (s *ViewSelector) meterVersionStr() string {
+	if s.MeterVersion == nil {
+		return ""
+	}
+	return *s.MeterVersion
+}
+
+func (s *ViewSelector) meterSchemaURLStr() string {
+	if s.MeterSchemaUrl == nil {
+		return ""
+	}
+	return *s.MeterSchemaUrl
+}
+
+func (s *ViewSelector) unitStr() string {
+	if s.Unit == nil {
+		return ""
+	}
+	return *s.Unit
+}
+
+func (s *ViewStream) nameStr() string {
+	if s.Name == nil {
+		return ""
+	}
+	return *s.Name
+}
+
+func (s *ViewStream) descriptionStr() string {
+	if s.Description == nil {
+		return ""
+	}
+	return *s.Description
+}
+
+func (e *ViewStreamAggregationExplicitBucketHistogram) recordMinMaxBool() bool {
+	if e.RecordMinMax == nil {
+		return false
+	}
+	return *e.RecordMinMax
+}