config.go

package traces

import (
	"encoding/base64"
	"errors"
	"fmt"
	"io/ioutil"
	"net"
	"sort"
	"time"

	"github.com/grafana/agent/pkg/logs"
	"github.com/grafana/agent/pkg/traces/automaticloggingprocessor"
	"github.com/grafana/agent/pkg/traces/noopreceiver"
	"github.com/grafana/agent/pkg/traces/promsdprocessor"
	"github.com/grafana/agent/pkg/traces/remotewriteexporter"
	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/loadbalancingexporter"
	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/spanmetricsprocessor"
	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/tailsamplingprocessor"
	"github.com/prometheus/client_golang/prometheus"
	prom_config "github.com/prometheus/common/config"
	"go.opentelemetry.io/collector/component"
	"go.opentelemetry.io/collector/config"
	"go.opentelemetry.io/collector/config/configloader"
	"go.opentelemetry.io/collector/config/configparser"
	"go.opentelemetry.io/collector/exporter/otlpexporter"
	"go.opentelemetry.io/collector/exporter/otlphttpexporter"
	"go.opentelemetry.io/collector/exporter/prometheusexporter"
	"go.opentelemetry.io/collector/processor/attributesprocessor"
	"go.opentelemetry.io/collector/processor/batchprocessor"
	"go.opentelemetry.io/collector/receiver/jaegerreceiver"
	"go.opentelemetry.io/collector/receiver/kafkareceiver"
	"go.opentelemetry.io/collector/receiver/opencensusreceiver"
	"go.opentelemetry.io/collector/receiver/otlpreceiver"
	"go.opentelemetry.io/collector/receiver/zipkinreceiver"
)

const (
	spanMetricsPipelineName = "metrics/spanmetrics"

	// defaultDecisionWait is the default time to wait for a trace before making a sampling decision
	defaultDecisionWait = time.Second * 5

	// defaultLoadBalancingPort is the default port the agent uses for internal load balancing
	defaultLoadBalancingPort = "4318"
	// agent's load balancing options
	dnsTagName    = "dns"
	staticTagName = "static"

	// sampling policies
	alwaysSamplePolicy     = "always_sample"
	stringAttributePolicy  = "string_attribute"
	numericAttributePolicy = "numeric_attribute"
	rateLimitingPolicy     = "rate_limiting"
	latencyPolicy          = "latency"
	statusCodePolicy       = "status_code"
)

// Config controls the configuration of Traces trace pipelines.
type Config struct {
	Configs []InstanceConfig `yaml:"configs,omitempty"`

	// Unmarshaled is true when the Config was unmarshaled from YAML.
	Unmarshaled bool `yaml:"-"`
}

// UnmarshalYAML implements yaml.Unmarshaler.
func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
	c.Unmarshaled = true
	type plain Config
	return unmarshal((*plain)(c))
}

// Validate ensures that the Config is valid.
func (c *Config) Validate(logsConfig *logs.Config) error {
	names := make(map[string]struct{}, len(c.Configs))
	for idx, c := range c.Configs {
		if c.Name == "" {
			return fmt.Errorf("traces config at index %d is missing a name", idx)
		}
		if _, exist := names[c.Name]; exist {
			return fmt.Errorf("found multiple traces configs with name %s", c.Name)
		}
		names[c.Name] = struct{}{}
	}

	for _, inst := range c.Configs {
		if inst.AutomaticLogging != nil {
			if err := inst.AutomaticLogging.Validate(logsConfig); err != nil {
				return fmt.Errorf("failed to validate automatic_logging for traces config %s: %w", inst.Name, err)
			}
		}
	}

	return nil
}

// InstanceConfig configures an individual Traces trace pipeline.
type InstanceConfig struct {
	Name string `yaml:"name"`

	// Deprecated in favor of RemoteWrite and Batch.
	PushConfig PushConfig `yaml:"push_config,omitempty"`

	// RemoteWrite defines one or multiple backends that can receive the pipeline's traffic.
	RemoteWrite []RemoteWriteConfig `yaml:"remote_write,omitempty"`

	// Receivers: https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/receiver/README.md
	Receivers map[string]interface{} `yaml:"receivers,omitempty"`

	// Batch: https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/processor/batchprocessor/config.go#L24
	Batch map[string]interface{} `yaml:"batch,omitempty"`

	// Attributes: https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/processor/attributesprocessor/config.go#L30
	Attributes map[string]interface{} `yaml:"attributes,omitempty"`

	// prom service discovery config
	ScrapeConfigs []interface{} `yaml:"scrape_configs,omitempty"`
	OperationType string        `yaml:"prom_sd_operation_type,omitempty"`

	// SpanMetricsProcessor: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/processor/spanmetricsprocessor/README.md
	SpanMetrics *SpanMetricsConfig `yaml:"spanmetrics,omitempty"`

	// AutomaticLogging
	AutomaticLogging *automaticloggingprocessor.AutomaticLoggingConfig `yaml:"automatic_logging,omitempty"`

	// TailSampling defines a sampling strategy for the pipeline
	TailSampling *tailSamplingConfig `yaml:"tail_sampling"`

	// LoadBalancing is used to distribute spans of the same trace to the same agent instance
	LoadBalancing *loadBalancingConfig `yaml:"load_balancing"`
}

const (
	compressionNone = "none"
	compressionGzip = "gzip"
	protocolGRPC    = "grpc"
	protocolHTTP    = "http"
)

// DefaultPushConfig holds the default settings for a PushConfig.
var DefaultPushConfig = PushConfig{
	Compression: compressionGzip,
}

// PushConfig controls the configuration of exporting to Grafana Cloud
type PushConfig struct {
	Endpoint           string                 `yaml:"endpoint,omitempty"`
	Compression        string                 `yaml:"compression,omitempty"`
	Insecure           bool                   `yaml:"insecure,omitempty"`
	InsecureSkipVerify bool                   `yaml:"insecure_skip_verify,omitempty"`
	BasicAuth          *prom_config.BasicAuth `yaml:"basic_auth,omitempty,omitempty"`
	Batch              map[string]interface{} `yaml:"batch,omitempty"`            // https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/processor/batchprocessor/config.go#L24
	SendingQueue       map[string]interface{} `yaml:"sending_queue,omitempty"`    // https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/exporter/exporterhelper/queued_retry.go#L30
	RetryOnFailure     map[string]interface{} `yaml:"retry_on_failure,omitempty"` // https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/exporter/exporterhelper/queued_retry.go#L54
}

// UnmarshalYAML implements yaml.Unmarshaler.
func (c *PushConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultPushConfig

	type plain PushConfig
	if err := unmarshal((*plain)(c)); err != nil {
		return err
	}

	if c.Compression != compressionGzip && c.Compression != compressionNone {
		return fmt.Errorf("unsupported compression '%s', expected 'gzip' or 'none'", c.Compression)
	}
	return nil
}

// DefaultRemoteWriteConfig holds the default settings for a PushConfig.
var DefaultRemoteWriteConfig = RemoteWriteConfig{
	Compression: compressionGzip,
	Protocol:    protocolGRPC,
}

// RemoteWriteConfig controls the configuration of an exporter
type RemoteWriteConfig struct {
	Endpoint    string `yaml:"endpoint,omitempty"`
	Compression string `yaml:"compression,omitempty"`
	Protocol    string `yaml:"protocol,omitempty"`
	Insecure    bool   `yaml:"insecure,omitempty"`
	// Deprecated
	InsecureSkipVerify bool                   `yaml:"insecure_skip_verify,omitempty"`
	TLSConfig          *prom_config.TLSConfig `yaml:"tls_config,omitempty"`
	BasicAuth          *prom_config.BasicAuth `yaml:"basic_auth,omitempty"`
	Headers            map[string]string      `yaml:"headers,omitempty"`
	SendingQueue       map[string]interface{} `yaml:"sending_queue,omitempty"`    // https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/exporter/exporterhelper/queued_retry.go#L30
	RetryOnFailure     map[string]interface{} `yaml:"retry_on_failure,omitempty"` // https://github.com/open-telemetry/opentelemetry-collector/blob/7d7ae2eb34b5d387627875c498d7f43619f37ee3/exporter/exporterhelper/queued_retry.go#L54
}

// UnmarshalYAML implements yaml.Unmarshaler.
func (c *RemoteWriteConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultRemoteWriteConfig

	type plain RemoteWriteConfig
	if err := unmarshal((*plain)(c)); err != nil {
		return err
	}

	if c.Compression != compressionGzip && c.Compression != compressionNone {
		return fmt.Errorf("unsupported compression '%s', expected 'gzip' or 'none'", c.Compression)
	}
	return nil
}

// SpanMetricsConfig controls the configuration of spanmetricsprocessor and the related metrics exporter.
type SpanMetricsConfig struct {
	LatencyHistogramBuckets []time.Duration                  `yaml:"latency_histogram_buckets,omitempty"`
	Dimensions              []spanmetricsprocessor.Dimension `yaml:"dimensions,omitempty"`
	// Namespace if set, exports metrics under the provided value.
	Namespace string `yaml:"namespace,omitempty"`
	// ConstLabels are values that are applied for every exported metric.
	ConstLabels *prometheus.Labels `yaml:"const_labels,omitempty"`
	// MetricsInstance is the Agent's metrics instance that will be used to push metrics
	MetricsInstance string `yaml:"metrics_instance"`
	// HandlerEndpoint is the address where a prometheus exporter will be exposed
	HandlerEndpoint string `yaml:"handler_endpoint"`
}

// tailSamplingConfig is the configuration for tail-based sampling
type tailSamplingConfig struct {
	// Policies are the strategies used for sampling. Multiple policies can be used in the same pipeline.
	// For more information, refer to https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/processor/tailsamplingprocessor
	Policies []map[string]interface{} `yaml:"policies"`
	// DecisionWait defines the time to wait for a complete trace before making a decision
	DecisionWait time.Duration `yaml:"decision_wait,omitempty"`
}

// loadBalancingConfig defines the configuration for load balancing spans between agent instances
// loadBalancingConfig is an OTel exporter's config with extra resolver config
type loadBalancingConfig struct {
	Exporter exporterConfig         `yaml:"exporter"`
	Resolver map[string]interface{} `yaml:"resolver"`
	// ReceiverPort is the port the instance will use to receive load balanced traces
	ReceiverPort string `yaml:"receiver_port"`
}

// exporterConfig defined the config for a otlp exporter for load balancing
type exporterConfig struct {
	Compression        string                 `yaml:"compression,omitempty"`
	Insecure           bool                   `yaml:"insecure,omitempty"`
	InsecureSkipVerify bool                   `yaml:"insecure_skip_verify,omitempty"`
	BasicAuth          *prom_config.BasicAuth `yaml:"basic_auth,omitempty"`
}

// exporter builds an OTel exporter from RemoteWriteConfig
func exporter(rwCfg RemoteWriteConfig) (map[string]interface{}, error) {
	if len(rwCfg.Endpoint) == 0 {
		return nil, errors.New("must have a configured a backend endpoint")
	}

	headers := map[string]string{}
	if rwCfg.Headers != nil {
		headers = rwCfg.Headers
	}

	if rwCfg.BasicAuth != nil {
		password := string(rwCfg.BasicAuth.Password)

		if len(rwCfg.BasicAuth.PasswordFile) > 0 {
			buff, err := ioutil.ReadFile(rwCfg.BasicAuth.PasswordFile)
			if err != nil {
				return nil, fmt.Errorf("unable to load password file %s: %w", rwCfg.BasicAuth.PasswordFile, err)
			}
			password = string(buff)
		}

		encodedAuth := base64.StdEncoding.EncodeToString([]byte(rwCfg.BasicAuth.Username + ":" + password))
		headers["authorization"] = "Basic " + encodedAuth
	}

	compression := rwCfg.Compression
	if compression == compressionNone {
		compression = ""
	}

	otlpExporter := map[string]interface{}{
		"endpoint":         rwCfg.Endpoint,
		"compression":      compression,
		"headers":          headers,
		"insecure":         rwCfg.Insecure,
		"sending_queue":    rwCfg.SendingQueue,
		"retry_on_failure": rwCfg.RetryOnFailure,
	}

	if !rwCfg.Insecure {
		// If there is a TLSConfig use it
		if rwCfg.TLSConfig != nil {
			otlpExporter["ca_file"] = rwCfg.TLSConfig.CAFile
			otlpExporter["cert_file"] = rwCfg.TLSConfig.CertFile
			otlpExporter["key_file"] = rwCfg.TLSConfig.KeyFile
			otlpExporter["insecure_skip_verify"] = rwCfg.TLSConfig.InsecureSkipVerify
		} else {
			// If not, set whatever value is specified in the old config.
			otlpExporter["insecure_skip_verify"] = rwCfg.InsecureSkipVerify
		}
	}

	// Apply some sane defaults to the exporter. The
	// sending_queue.retry_on_failure default is 300s which prevents any
	// sending-related errors to not be logged for 5 minutes. We'll lower that
	// to 60s.
	if retryConfig := otlpExporter["retry_on_failure"].(map[string]interface{}); retryConfig == nil {
		otlpExporter["retry_on_failure"] = map[string]interface{}{
			"max_elapsed_time": "60s",
		}
	} else if retryConfig["max_elapsed_time"] == nil {
		retryConfig["max_elapsed_time"] = "60s"
	}

	return otlpExporter, nil
}

// exporters builds one or multiple exporters from a remote_write block.
// It also supports building an exporter from push_config.
func (c *InstanceConfig) exporters() (map[string]interface{}, error) {
	if len(c.RemoteWrite) == 0 {
		otlpExporter, err := exporter(RemoteWriteConfig{
			Endpoint:    c.PushConfig.Endpoint,
			Compression: c.PushConfig.Compression,
			Insecure:    c.PushConfig.Insecure,
			TLSConfig: &prom_config.TLSConfig{
				InsecureSkipVerify: c.PushConfig.InsecureSkipVerify,
			},
			BasicAuth:      c.PushConfig.BasicAuth,
			SendingQueue:   c.PushConfig.SendingQueue,
			RetryOnFailure: c.PushConfig.RetryOnFailure,
		})
		return map[string]interface{}{
			"otlp": otlpExporter,
		}, err
	}

	exporters := map[string]interface{}{}
	for i, remoteWriteConfig := range c.RemoteWrite {
		exporter, err := exporter(remoteWriteConfig)
		if err != nil {
			return nil, err
		}
		var exporterName string
		switch remoteWriteConfig.Protocol {
		case protocolGRPC:
			exporterName = fmt.Sprintf("otlp/%d", i)
		case protocolHTTP:
			exporterName = fmt.Sprintf("otlphttp/%d", i)
		}
		exporters[exporterName] = exporter
	}
	return exporters, nil
}

func resolver(config map[string]interface{}) (map[string]interface{}, error) {
	if len(config) == 0 {
		return nil, fmt.Errorf("must configure one resolver (dns or static)")
	}
	resolverCfg := make(map[string]interface{})
	for typ, cfg := range config {
		switch typ {
		case dnsTagName, staticTagName:
			resolverCfg[typ] = cfg
		default:
			return nil, fmt.Errorf("unsupported resolver config type: %s", typ)
		}
	}
	return resolverCfg, nil
}

func (c *InstanceConfig) loadBalancingExporter() (map[string]interface{}, error) {
	exporter, err := exporter(RemoteWriteConfig{
		// Endpoint is omitted in OTel load balancing exporter
		Endpoint:    "noop",
		Compression: c.LoadBalancing.Exporter.Compression,
		Insecure:    c.LoadBalancing.Exporter.Insecure,
		TLSConfig:   &prom_config.TLSConfig{InsecureSkipVerify: c.LoadBalancing.Exporter.InsecureSkipVerify},
		BasicAuth:   c.LoadBalancing.Exporter.BasicAuth,
	})
	if err != nil {
		return nil, err
	}
	resolverCfg, err := resolver(c.LoadBalancing.Resolver)
	if err != nil {
		return nil, err
	}
	return map[string]interface{}{
		"protocol": map[string]interface{}{
			"otlp": exporter,
		},
		"resolver": resolverCfg,
	}, nil
}

// formatPolicies creates sampling policies (i.e. rules) compatible with OTel's tail sampling processor
// https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/v0.21.0/processor/tailsamplingprocessor
func formatPolicies(cfg []map[string]interface{}) ([]map[string]interface{}, error) {
	policies := make([]map[string]interface{}, 0, len(cfg))
	for i, policy := range cfg {
		if len(policy) != 1 {
			return nil, errors.New("malformed sampling policy")
		}
		for typ, rules := range policy {
			switch typ {
			case alwaysSamplePolicy:
				policies = append(policies, map[string]interface{}{
					"name": fmt.Sprintf("%s/%d", typ, i),
					"type": typ,
				})
			case stringAttributePolicy, rateLimitingPolicy, numericAttributePolicy, latencyPolicy, statusCodePolicy:
				policies = append(policies, map[string]interface{}{
					"name": fmt.Sprintf("%s/%d", typ, i),
					"type": typ,
					typ:    rules,
				})
			default:
				return nil, fmt.Errorf("unsupported policy type %s", typ)
			}
		}
	}
	return policies, nil
}

func (c *InstanceConfig) otelConfig() (*config.Config, error) {
	otelMapStructure := map[string]interface{}{}

	if len(c.Receivers) == 0 {
		return nil, errors.New("must have at least one configured receiver")
	}

	if len(c.RemoteWrite) != 0 && len(c.PushConfig.Endpoint) != 0 {
		return nil, errors.New("must not configure push_config and remote_write. push_config is deprecated in favor of remote_write")
	}

	if c.Batch != nil && c.PushConfig.Batch != nil {
		return nil, errors.New("must not configure push_config.batch and batch. push_config.batch is deprecated in favor of batch")
	}

	exporters, err := c.exporters()
	if err != nil {
		return nil, err
	}
	exportersNames := make([]string, 0, len(exporters))
	for name := range exporters {
		exportersNames = append(exportersNames, name)
	}

	// processors
	processors := map[string]interface{}{}
	processorNames := []string{}
	if c.ScrapeConfigs != nil {
		opType := promsdprocessor.OperationTypeUpsert
		if c.OperationType != "" {
			opType = c.OperationType
		}
		processorNames = append(processorNames, promsdprocessor.TypeStr)
		processors[promsdprocessor.TypeStr] = map[string]interface{}{
			"scrape_configs": c.ScrapeConfigs,
			"operation_type": opType,
		}
	}

	if c.AutomaticLogging != nil {
		processorNames = append(processorNames, automaticloggingprocessor.TypeStr)
		processors[automaticloggingprocessor.TypeStr] = map[string]interface{}{
			"automatic_logging": c.AutomaticLogging,
		}
	}

	if c.Attributes != nil {
		processors["attributes"] = c.Attributes
		processorNames = append(processorNames, "attributes")
	}

	if c.Batch != nil {
		processors["batch"] = c.Batch
		processorNames = append(processorNames, "batch")
	} else if c.PushConfig.Batch != nil {
		processors["batch"] = c.PushConfig.Batch
		processorNames = append(processorNames, "batch")
	}

	pipelines := make(map[string]interface{})
	if c.SpanMetrics != nil {
		// Configure the metrics exporter.
		namespace := "traces_spanmetrics"
		if len(c.SpanMetrics.Namespace) != 0 {
			namespace = fmt.Sprintf("%s_%s", c.SpanMetrics.Namespace, namespace)
		}

		var exporterName string
		if len(c.SpanMetrics.MetricsInstance) != 0 && len(c.SpanMetrics.HandlerEndpoint) == 0 {
			exporterName = remotewriteexporter.TypeStr
			exporters[remotewriteexporter.TypeStr] = map[string]interface{}{
				"namespace":        namespace,
				"const_labels":     c.SpanMetrics.ConstLabels,
				"metrics_instance": c.SpanMetrics.MetricsInstance,
			}
		} else if len(c.SpanMetrics.MetricsInstance) == 0 && len(c.SpanMetrics.HandlerEndpoint) != 0 {
			exporterName = "prometheus"
			exporters[exporterName] = map[string]interface{}{
				"endpoint":     c.SpanMetrics.HandlerEndpoint,
				"namespace":    namespace,
				"const_labels": c.SpanMetrics.ConstLabels,
			}
		} else {
			return nil, fmt.Errorf("must specify a prometheus instance or a metrics handler endpoint to export the metrics")
		}

		processorNames = append(processorNames, "spanmetrics")
		processors["spanmetrics"] = map[string]interface{}{
			"metrics_exporter":          exporterName,
			"latency_histogram_buckets": c.SpanMetrics.LatencyHistogramBuckets,
			"dimensions":                c.SpanMetrics.Dimensions,
		}

		pipelines[spanMetricsPipelineName] = map[string]interface{}{
			"receivers": []string{noopreceiver.TypeStr},
			"exporters": []string{exporterName},
		}
	}

	// receivers
	receiverNames := []string{}
	for name := range c.Receivers {
		receiverNames = append(receiverNames, name)
	}

	if c.TailSampling != nil {
		wait := defaultDecisionWait
		if c.TailSampling.DecisionWait != 0 {
			wait = c.TailSampling.DecisionWait
		}

		policies, err := formatPolicies(c.TailSampling.Policies)
		if err != nil {
			return nil, err
		}

		// tail_sampling should be executed before the batch processor
		// TODO(mario.rodriguez): put attributes processor before tail_sampling. Maybe we want to sample on mutated spans
		processorNames = append([]string{"tail_sampling"}, processorNames...)
		processors["tail_sampling"] = map[string]interface{}{
			"policies":      policies,
			"decision_wait": wait,
		}
	}

	if c.LoadBalancing != nil {
		internalExporter, err := c.loadBalancingExporter()
		if err != nil {
			return nil, err
		}
		exporters["loadbalancing"] = internalExporter

		receiverPort := defaultLoadBalancingPort
		if c.LoadBalancing.ReceiverPort != "" {
			receiverPort = c.LoadBalancing.ReceiverPort
		}
		c.Receivers["otlp/lb"] = map[string]interface{}{
			"protocols": map[string]interface{}{
				"grpc": map[string]interface{}{
					"endpoint": net.JoinHostPort("0.0.0.0", receiverPort),
				},
			},
		}
	}

	// Build Pipelines
	splitPipeline := c.LoadBalancing != nil
	orderedSplitProcessors := orderProcessors(processorNames, splitPipeline)
	if splitPipeline {
		// load balancing pipeline
		pipelines["traces/0"] = map[string]interface{}{
			"receivers":  receiverNames,
			"processors": orderedSplitProcessors[0],
			"exporters":  []string{"loadbalancing"},
		}
		// processing pipeline
		pipelines["traces/1"] = map[string]interface{}{
			"exporters":  exportersNames,
			"processors": orderedSplitProcessors[1],
			"receivers":  []string{"otlp/lb"},
		}
	} else {
		pipelines["traces"] = map[string]interface{}{
			"exporters":  exportersNames,
			"processors": orderedSplitProcessors[0],
			"receivers":  receiverNames,
		}
	}

	if c.SpanMetrics != nil {
		// Insert a noop receiver in the metrics pipeline.
		// Added to pass validation requiring at least one receiver in a pipeline.
		c.Receivers[noopreceiver.TypeStr] = nil
	}

	otelMapStructure["exporters"] = exporters
	otelMapStructure["processors"] = processors
	otelMapStructure["receivers"] = c.Receivers

	// pipelines
	otelMapStructure["service"] = map[string]interface{}{
		"pipelines": pipelines,
	}

	factories, err := tracingFactories()
	if err != nil {
		return nil, fmt.Errorf("failed to create factories: %w", err)
	}

	parser := configparser.NewParserFromStringMap(otelMapStructure)
	otelCfg, err := configloader.Load(parser, factories)
	if err != nil {
		return nil, fmt.Errorf("failed to load OTel config: %w", err)
	}

	return otelCfg, nil
}

// tracingFactories() only creates the needed factories.  if we decide to add support for a new
// processor, exporter, receiver we need to add it here
func tracingFactories() (component.Factories, error) {
	extensions, err := component.MakeExtensionFactoryMap()
	if err != nil {
		return component.Factories{}, err
	}

	receivers, err := component.MakeReceiverFactoryMap(
		jaegerreceiver.NewFactory(),
		zipkinreceiver.NewFactory(),
		otlpreceiver.NewFactory(),
		opencensusreceiver.NewFactory(),
		kafkareceiver.NewFactory(),
		noopreceiver.NewFactory(),
	)
	if err != nil {
		return component.Factories{}, err
	}

	exporters, err := component.MakeExporterFactoryMap(
		otlpexporter.NewFactory(),
		otlphttpexporter.NewFactory(),
		loadbalancingexporter.NewFactory(),
		prometheusexporter.NewFactory(),
		remotewriteexporter.NewFactory(),
	)
	if err != nil {
		return component.Factories{}, err
	}

	processors, err := component.MakeProcessorFactoryMap(
		batchprocessor.NewFactory(),
		attributesprocessor.NewFactory(),
		promsdprocessor.NewFactory(),
		spanmetricsprocessor.NewFactory(),
		automaticloggingprocessor.NewFactory(),
		tailsamplingprocessor.NewFactory(),
	)
	if err != nil {
		return component.Factories{}, err
	}

	return component.Factories{
		Extensions: extensions,
		Receivers:  receivers,
		Processors: processors,
		Exporters:  exporters,
	}, nil
}

// orders the passed processors into their preferred order in a tracing pipeline. pass
// true to splitPipelines if this function should split the input pipelines into two
// sets: before and after load balancing
func orderProcessors(processors []string, splitPipelines bool) [][]string {
	order := map[string]int{
		"attributes":        0,
		"spanmetrics":       1,
		"tail_sampling":     2,
		"automatic_logging": 3,
		"batch":             4,
	}

	sort.Slice(processors, func(i, j int) bool {
		iVal := order[processors[i]]
		jVal := order[processors[j]]

		return iVal < jVal
	})

	if !splitPipelines {
		return [][]string{
			processors,
		}
	}

	// if we're splitting pipelines we have to look for the first processor that belongs in the second
	// stage and split on that. if nothing belongs in the second stage just leave them all in the first
	foundAt := len(processors)
	for i, processor := range processors {
		if processor == "batch" ||
			processor == "tail_sampling" ||
			processor == "automatic_logging" {
			foundAt = i
			break
		}
	}

	return [][]string{
		processors[:foundAt],
		processors[foundAt:],
	}
}