[WIP] Make Node-exporter embeddable in OpenTelemetry Collectors

collector/collector.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/alecthomas/kingpin/v2"
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/procfs"
 )
 
 // Namespace defines the common namespace to be used by all metrics.
@@ -53,7 +54,8 @@ var (
 	initiatedCollectorsMtx = sync.Mutex{}
 	initiatedCollectors    = make(map[string]Collector)
 	collectorState         = make(map[string]*bool)
-	forcedCollectors       = map[string]bool{} // collectors which have been explicitly enabled or disabled
+	forcedCollectors       = map[string]bool{}     // collectors which have been explicitly enabled or disabled
+	collectorDefaults      = make(map[string]bool) // tracks default enabled/disabled state for OTEL context
 )
 
 func registerCollector(collector string, isDefaultEnabled bool, factory func(logger *slog.Logger) (Collector, error)) {
@@ -64,6 +66,9 @@ func registerCollector(collector string, isDefaultEnabled bool, factory func(log
 		helpDefaultState = "disabled"
 	}
 
+	// Store the default state for OTEL context initialization
+	collectorDefaults[collector] = isDefaultEnabled
+
 	flagName := fmt.Sprintf("collector.%s", collector)
 	flagHelp := fmt.Sprintf("Enable the %s collector (default: %s).", collector, helpDefaultState)
 	defaultValue := fmt.Sprintf("%v", isDefaultEnabled)
@@ -243,3 +248,43 @@ func pushMetric(ch chan<- prometheus.Metric, fieldDesc *prometheus.Desc, name st
 
 	ch <- prometheus.MustNewConstMetric(fieldDesc, valueType, fVal, labelValues...)
 }
+
+// InitializeCollectorStateForOTEL initializes the collector state for OTEL context
+// without relying on kingpin flag parsing. This should be called before creating
+// any NodeCollector instances in the OTEL context.
+func InitializeCollectorStateForOTEL() {
+	// Initialize collector enable/disable state from stored defaults
+	for collectorName, defaultEnabled := range collectorDefaults {
+		enabled := defaultEnabled
+		collectorState[collectorName] = &enabled
+	}
+
+	// Initialize collector-specific configuration flags with their defaults
+	initializeCollectorFlags()
+}
+
+// initializeCollectorFlags sets default values for collector-specific flags
+// that are normally initialized by kingpin parsing
+func initializeCollectorFlags() {
+	// Initialize path flags with their defaults (from paths.go)
+	if procPath == nil {
+		defaultProcPath := procfs.DefaultMountPoint
+		procPath = &defaultProcPath
+	}
+	if sysPath == nil {
+		defaultSysPath := "/sys"
+		sysPath = &defaultSysPath
+	}
+	if rootfsPath == nil {
+		defaultRootfsPath := "/"
+		rootfsPath = &defaultRootfsPath
+	}
+	if udevDataPath == nil {
+		defaultUdevDataPath := "/run/udev/data"
+		udevDataPath = &defaultUdevDataPath
+	}
+
+	// Initialize other collector-specific flags with empty/default values
+	// These will be nil pointers until kingpin.Parse() is called, but collectors
+	// should handle nil gracefully or we can initialize them as needed
+}

otelcollector/config.go

@@ -0,0 +1,29 @@
+// Copyright The Prometheus 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 otelcollector
+
+import "fmt"
+
+type Config struct {
+	DisableDefaults   bool     `mapstructure:"disable_defaults"`
+	EnableCollectors  []string `mapstructure:"enable_collectors"`
+	ExcludeCollectors []string `mapstructure:"exclude_collectors"`
+}
+
+func (c Config) Validate() error {
+	if len(c.EnableCollectors) > 0 && len(c.ExcludeCollectors) > 0 {
+		return fmt.Errorf("%q and %q can't be used at the same time", "EnableCollectors", "ExcludeCollectors")
+	}
+	return nil
+}

otelcollector/doc.go

@@ -0,0 +1,19 @@
+// Copyright The Prometheus 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 otelcollector implements the OpenTelemetry Collector receiver interface
+// for the Prometheus Node Exporter.
+//
+// Use this go module to embed the Prometheus Node Exporter in your OpenTelemetry Collector
+// using OCB (OpenTelemetry Collector Builder).
+package otelcollector

otelcollector/exporter.go

@@ -0,0 +1,131 @@
+// Copyright The Prometheus 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 otelcollector
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+
+	"github.com/prometheus/client_golang/prometheus"
+	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
+	"github.com/prometheus/exporter-toolkit/otlpreceiver"
+	"github.com/prometheus/node_exporter/collector"
+)
+
+type NodeExporter struct {
+	config   *Config
+	registry *prometheus.Registry
+}
+
+func NewNodeExporter(config *Config) *NodeExporter {
+	return &NodeExporter{
+		config:   config,
+		registry: prometheus.NewRegistry(),
+	}
+}
+
+func (ne *NodeExporter) Initialize(ctx context.Context, cfg otlpreceiver.Config) (*prometheus.Registry, error) {
+	if cfg != nil {
+		var ok bool
+		ne.config, ok = cfg.(*Config)
+		if !ok {
+			return nil, errors.New("error reading configuration")
+		}
+	} else {
+		// Use default configuration when none is provided
+		ne.config = &Config{
+			DisableDefaults:   false,
+			EnableCollectors:  []string{},
+			ExcludeCollectors: []string{},
+		}
+	}
+
+	// Create logger for collectors
+	logger := slog.Default().With("component", "node_exporter")
+
+	collector.InitializeCollectorStateForOTEL()
+
+	// Apply disable defaults configuration
+	if ne.config.DisableDefaults {
+		collector.DisableDefaultCollectors()
+	}
+
+	// Determine which collectors to create based on configuration
+	var filters []string
+
+	// Validate that both EnableCollectors and ExcludeCollectors are not used together
+	if len(ne.config.EnableCollectors) > 0 && len(ne.config.ExcludeCollectors) > 0 {
+		return nil, fmt.Errorf("enable_collectors and exclude_collectors cannot be used together")
+	}
+
+	if len(ne.config.EnableCollectors) > 0 {
+		// If specific collectors are enabled, use only those
+		filters = ne.config.EnableCollectors
+	} else if len(ne.config.ExcludeCollectors) > 0 {
+		// If excludes are specified, we need to create a list of all enabled collectors
+		// minus the excluded ones, similar to how the main node_exporter handles it
+		filters = []string{}
+
+		// First, create a temporary NodeCollector to get the list of enabled collectors
+		tempNC, err := collector.NewNodeCollector(logger)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get available collectors: %w", err)
+		}
+
+		// Get all enabled collector names
+		for collectorName := range tempNC.Collectors {
+			// Check if this collector is not in the exclude list
+			excluded := false
+			for _, excludeName := range ne.config.ExcludeCollectors {
+				if collectorName == excludeName {
+					excluded = true
+					break
+				}
+			}
+			if !excluded {
+				filters = append(filters, collectorName)
+			}
+		}
+	}
+	// If neither EnableCollectors nor ExcludeCollectors are specified,
+	// filters remains empty and NewNodeCollector will use all enabled collectors
+
+	// Create the node collector with all enabled collectors
+	nc, err := collector.NewNodeCollector(logger, filters...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create node collector: %w", err)
+	}
+
+	// Register version collector
+	ne.registry.MustRegister(versioncollector.NewCollector("node_exporter"))
+
+	// Register the node collector
+	if err := ne.registry.Register(nc); err != nil {
+		return nil, fmt.Errorf("failed to register node collector: %w", err)
+	}
+
+	logger.Info("Node exporter initialized successfully",
+		"disable_defaults", ne.config.DisableDefaults,
+		"enable_collectors", ne.config.EnableCollectors,
+		"exclude_collectors", ne.config.ExcludeCollectors)
+
+	return ne.registry, nil
+}
+
+func (ne *NodeExporter) Shutdown(_ context.Context) error {
+	// There's nothing special needed to shutdown node-exporter.
+	return nil
+}

otelcollector/factory.go

@@ -0,0 +1,36 @@
+// Copyright The Prometheus 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 otelcollector
+
+import (
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/receiver"
+
+	"github.com/prometheus/exporter-toolkit/otlpreceiver"
+)
+
+func NewFactory() receiver.Factory {
+	defaults := map[string]interface{}{
+		"disable_defaults":   false,
+		"enable_collectors":  []string{},
+		"exclude_collectors": []string{},
+	}
+
+	return otlpreceiver.NewFactory(
+		otlpreceiver.WithType(component.MustNewType("prometheus_node_exporter")),
+		otlpreceiver.WithInitializer(NewNodeExporter(&Config{})),
+		otlpreceiver.WithConfigUnmarshaler(&ConfigUnmarshaler{}),
+		otlpreceiver.WithComponentDefaults(defaults),
+	)
+}

otelcollector/go.mod

@@ -0,0 +1,81 @@
+module github.com/prometheus/node_exporter/otel_collector
+
+go 1.25.0
+
+require (
+	github.com/prometheus/client_golang v1.23.2
+	github.com/prometheus/exporter-toolkit v0.14.1
+	github.com/prometheus/node_exporter v1.10.2
+	go.opentelemetry.io/collector/component v1.44.0
+	go.opentelemetry.io/collector/receiver v1.44.0
+)
+
+require (
+	github.com/alecthomas/kingpin/v2 v2.4.0 // indirect
+	github.com/alecthomas/units v0.0.0-20240927000941-0f3dac36c52b // indirect
+	github.com/beevik/ntp v1.5.0 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/coreos/go-systemd/v22 v22.6.0 // indirect
+	github.com/dennwc/btrfs v0.0.0-20241002142654-12ae127e0bf6 // indirect
+	github.com/dennwc/ioctl v1.0.0 // indirect
+	github.com/ema/qdisc v1.0.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/google/go-cmp v0.7.0 // indirect
+	github.com/hashicorp/go-envparse v0.1.0 // indirect
+	github.com/hashicorp/go-version v1.7.0 // indirect
+	github.com/hodgesds/perf-utils v0.7.0 // indirect
+	github.com/illumos/go-kstat v0.0.0-20210513183136-173c9b0a9973 // indirect
+	github.com/jsimonetti/rtnetlink/v2 v2.0.5 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/lufia/iostat v1.2.1 // indirect
+	github.com/mattn/go-xmlrpc v0.0.3 // indirect
+	github.com/mdlayher/ethtool v0.5.0 // indirect
+	github.com/mdlayher/genetlink v1.3.2 // indirect
+	github.com/mdlayher/netlink v1.8.0 // indirect
+	github.com/mdlayher/socket v0.5.1 // indirect
+	github.com/mdlayher/wifi v0.6.0 // indirect
+	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/opencontainers/selinux v1.12.0 // indirect
+	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
+	github.com/prometheus-community/go-runit v0.1.0 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.67.1 // indirect
+	github.com/prometheus/procfs v0.19.0 // indirect
+	github.com/safchain/ethtool v0.6.2 // indirect
+	github.com/xhit/go-str2duration/v2 v2.1.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/collector/consumer v1.44.0 // indirect
+	go.opentelemetry.io/collector/featuregate v1.44.0 // indirect
+	go.opentelemetry.io/collector/internal/telemetry v0.138.0 // indirect
+	go.opentelemetry.io/collector/pdata v1.44.0 // indirect
+	go.opentelemetry.io/collector/pipeline v1.44.0 // indirect
+	go.opentelemetry.io/contrib/bridges/otelzap v0.13.0 // indirect
+	go.opentelemetry.io/otel v1.38.0 // indirect
+	go.opentelemetry.io/otel/log v0.14.0 // indirect
+	go.opentelemetry.io/otel/metric v1.38.0 // indirect
+	go.opentelemetry.io/otel/trace v1.38.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.3 // indirect
+	golang.org/x/crypto v0.43.0 // indirect
+	golang.org/x/exp v0.0.0-20250911091902-df9299821621 // indirect
+	golang.org/x/net v0.45.0 // indirect
+	golang.org/x/sync v0.17.0 // indirect
+	golang.org/x/sys v0.37.0 // indirect
+	golang.org/x/text v0.30.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250825161204-c5933d9347a5 // indirect
+	google.golang.org/grpc v1.76.0 // indirect
+	google.golang.org/protobuf v1.36.10 // indirect
+	howett.net/plist v1.0.1 // indirect
+)
+
+replace github.com/prometheus/exporter-toolkit => ../../exporter-toolkit
+
+replace github.com/prometheus/node_exporter => ../