[OTel] Introduce otel subcommand (#4159)

* Added otel subcommand

* test update

* lint

* notice

* added unit tests

Author: michalpristas

NOTICE.txt

@@ -6139,6 +6139,44 @@ Contents of probable licence file $GOMODCACHE/github.com/spf13/cobra@v1.8.0/LICE
       of your accepting any such warranty or additional liability.
 
 
+--------------------------------------------------------------------------------
+Dependency : github.com/spf13/pflag
+Version: v1.0.5
+Licence type (autodetected): BSD-3-Clause
+--------------------------------------------------------------------------------
+
+Contents of probable licence file $GOMODCACHE/github.com/spf13/pflag@v1.0.5/LICENSE:
+
+Copyright (c) 2012 Alex Ogier. All rights reserved.
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
 --------------------------------------------------------------------------------
 Dependency : github.com/stretchr/testify
 Version: v1.8.4
@@ -26663,44 +26701,6 @@ Contents of probable licence file $GOMODCACHE/github.com/spf13/afero@v1.9.5/LICE
       of your accepting any such warranty or additional liability.
 
 
---------------------------------------------------------------------------------
-Dependency : github.com/spf13/pflag
-Version: v1.0.5
-Licence type (autodetected): BSD-3-Clause
---------------------------------------------------------------------------------
-
-Contents of probable licence file $GOMODCACHE/github.com/spf13/pflag@v1.0.5/LICENSE:
-
-Copyright (c) 2012 Alex Ogier. All rights reserved.
-Copyright (c) 2012 The Go Authors. All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-   * Redistributions of source code must retain the above copyright
-notice, this list of conditions and the following disclaimer.
-   * Redistributions in binary form must reproduce the above
-copyright notice, this list of conditions and the following disclaimer
-in the documentation and/or other materials provided with the
-distribution.
-   * Neither the name of Google Inc. nor the names of its
-contributors may be used to endorse or promote products derived from
-this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-
 --------------------------------------------------------------------------------
 Dependency : github.com/stretchr/objx
 Version: v0.5.0

go.mod

@@ -54,6 +54,7 @@ require (
 	github.com/shirou/gopsutil/v3 v3.23.12
 	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.8.0
+	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.8.4
 	github.com/tsg/go-daemon v0.0.0-20200207173439-e704b93fd89b
 	go.elastic.co/apm/module/apmgorilla v1.15.0
@@ -187,7 +188,6 @@ require (
 	github.com/sergi/go-diff v1.2.0 // indirect
 	github.com/shirou/gopsutil v3.21.11+incompatible // indirect
 	github.com/shoenig/go-m1cpu v0.1.6 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
 	github.com/tklauser/go-sysconf v0.3.12 // indirect
 	github.com/tklauser/numcpus v0.6.1 // indirect

internal/pkg/agent/application/application.go

@@ -134,6 +134,9 @@ func New(
 
 		// testing mode uses a config manager that takes configuration from over the control protocol
 		configMgr = newTestingModeConfigManager(log)
+	} else if runAsOtel {
+		// ignoring configuration in elastic-agent.yml
+		configMgr = otel.NewOtelModeConfigManager()
 	} else if configuration.IsStandalone(cfg.Fleet) {
 		log.Info("Parsed configuration and determined agent is managed locally")
 
@@ -146,9 +149,6 @@ func New(
 			log.Debugf("Reloading of configuration is on, frequency is set to %s", cfg.Settings.Reload.Period)
 			configMgr = newPeriodic(log, cfg.Settings.Reload.Period, discover, loader)
 		}
-	} else if runAsOtel {
-		// ignoring configuration in elastic-agent.yml
-		configMgr = otel.NewOtelModeConfigManager()
 	} else {
 		isManaged = true
 		var store storage.Store

internal/pkg/agent/application/paths/common.go

@@ -24,6 +24,8 @@ import (
 const (
 	// DefaultConfigName is the default name of the configuration file.
 	DefaultConfigName = "elastic-agent.yml"
+	// DefaultOtelConfigName is the default name of the otel configuration file.
+	DefaultOtelConfigName = "otel.yml"
 
 	// AgentLockFileName is the name of the overall Elastic Agent file lock.
 	AgentLockFileName = "agent.lock"
@@ -151,8 +153,19 @@ func SetConfig(path string) {
 
 // ConfigFile returns the path to the configuration file.
 func ConfigFile() string {
+
+	return configFileWithDefaultOverride(DefaultConfigName)
+}
+
+// OtelConfigFile returns the path to the otel configuration file.
+func OtelConfigFile() string {
+	return configFileWithDefaultOverride(DefaultOtelConfigName)
+}
+
+// configFileWithDefaultOverride returns the path to the configuration file overriding default value.
+func configFileWithDefaultOverride(defaultConfig string) string {
 	if configFilePath == "" || configFilePath == DefaultConfigName {
-		return filepath.Join(Config(), DefaultConfigName)
+		return filepath.Join(Config(), defaultConfig)
 	}
 	if filepath.IsAbs(configFilePath) {
 		return configFilePath

internal/pkg/agent/cmd/common.go

@@ -81,6 +81,7 @@ func NewCommandWithArgs(args []string, streams *cli.IOStreams) *cobra.Command {
 	cmd.AddCommand(newDiagnosticsCommand(args, streams))
 	cmd.AddCommand(newComponentCommandWithArgs(args, streams))
 	cmd.AddCommand(newLogsCommandWithArgs(args, streams))
+	cmd.AddCommand(newOtelCommandWithArgs(args, streams))
 
 	// windows special hidden sub-command (only added on Windows)
 	reexec := newReExecWindowsCommand(args, streams)

internal/pkg/agent/cmd/otel.go

@@ -0,0 +1,125 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package cmd
+
+import (
+	"context"
+	"sync"
+
+	"github.com/hashicorp/go-multierror"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+
+	"github.com/elastic/elastic-agent-libs/service"
+	"github.com/elastic/elastic-agent/internal/pkg/agent/errors"
+	"github.com/elastic/elastic-agent/internal/pkg/cli"
+	"github.com/elastic/elastic-agent/internal/pkg/otel"
+)
+
+const (
+	configFlagName = "config"
+	setFlagName    = "set"
+)
+
+func newOtelCommandWithArgs(_ []string, _ *cli.IOStreams) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "otel",
+		Short: "Start the Elastic Agent in otel mode",
+		Long:  "This command starts the Elastic Agent in otel mode.",
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			cfgFiles, err := getConfigFiles(cmd)
+			if err != nil {
+				return err
+			}
+			return runCollector(cmd.Context(), cfgFiles)
+		},
+		PreRun: func(c *cobra.Command, args []string) {
+			// hide inherited flags not to bloat help with flags not related to otel
+			hideInheritedFlags(c)
+		},
+		SilenceUsage:  true,
+		SilenceErrors: true,
+	}
+
+	cmd.SetHelpFunc(func(c *cobra.Command, s []string) {
+		hideInheritedFlags(c)
+		c.Parent().HelpFunc()(c, s)
+	})
+
+	cmd.Flags().StringArray(configFlagName, []string{}, "Locations to the config file(s), note that only a"+
+		" single location can be set per flag entry e.g. `--config=file:/path/to/first --config=file:path/to/second`.")
+
+	cmd.Flags().StringArray(setFlagName, []string{}, "Set arbitrary component config property. The component has to be defined in the config file and the flag"+
+		" has a higher precedence. Array config properties are overridden and maps are joined. Example --set=processors.batch.timeout=2s")
+	return cmd
+}
+
+func hideInheritedFlags(c *cobra.Command) {
+	c.InheritedFlags().VisitAll(func(f *pflag.Flag) {
+		f.Hidden = true
+	})
+}
+
+func runCollector(cmdCtx context.Context, configFiles []string) error {
+	// Windows: Mark service as stopped.
+	// After this is run, the service is considered by the OS to be stopped.
+	// This must be the first deferred cleanup task (last to execute).
+	defer func() {
+		service.NotifyTermination()
+		service.WaitExecutionDone()
+	}()
+
+	service.BeforeRun()
+	defer service.Cleanup()
+
+	stop := make(chan bool)
+	ctx, cancel := context.WithCancel(cmdCtx)
+
+	var stopCollector = func() {
+		close(stop)
+	}
+
+	defer cancel()
+	go service.ProcessWindowsControlEvents(stopCollector)
+
+	var otelStartWg sync.WaitGroup
+	var resErr error
+	var awaiters awaiters
+
+	otelAwaiter := make(chan struct{})
+	awaiters = append(awaiters, otelAwaiter)
+
+	otelStartWg.Add(1)
+	go func() {
+		otelStartWg.Done()
+		if err := otel.Run(ctx, stop, configFiles); err != nil {
+			resErr = multierror.Append(resErr, err)
+			// otel collector finished with an error, exit run loop
+			cancel()
+		}
+
+		// close awaiter handled in run loop
+		close(otelAwaiter)
+	}()
+
+	// wait for otel to start
+	otelStartWg.Wait()
+
+	if err := runElasticAgent(
+		ctx,
+		cancel,
+		nil,      // no config overrides
+		stop,     // service hook
+		false,    // not in testing mode
+		0,        // no fleet config
+		true,     // is otel mode
+		awaiters, // wait for otel to finish
+	); err != nil && !errors.Is(err, context.Canceled) {
+		resErr = multierror.Append(resErr, err)
+	}
+
+	return resErr
+
+}

internal/pkg/agent/cmd/otel_flags.go

@@ -0,0 +1,57 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package cmd
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"github.com/elastic/elastic-agent/internal/pkg/agent/application/paths"
+)
+
+func getConfigFiles(cmd *cobra.Command) ([]string, error) {
+	configFiles, err := cmd.Flags().GetStringArray(configFlagName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve config flags: %w", err)
+	}
+
+	if len(configFiles) == 0 {
+		configFiles = append(configFiles, paths.OtelConfigFile())
+	}
+
+	setVals, err := cmd.Flags().GetStringArray(setFlagName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve set flags: %w", err)
+	}
+
+	sets, err := getSets(setVals)
+	if err != nil {
+		return nil, err
+	}
+
+	configFiles = append(configFiles, sets...)
+	return configFiles, nil
+}
+
+func getSets(setVals []string) ([]string, error) {
+	var sets []string
+	for _, s := range setVals {
+		idx := strings.Index(s, "=")
+		if idx == -1 {
+			return nil, fmt.Errorf("missing equal sign for set value %q", s)
+		}
+		sets = append(sets, setToYaml(s, idx))
+	}
+	return sets, nil
+}
+
+func setToYaml(set string, eqIdx int) string {
+	if len(set) == 0 {
+		return set
+	}
+	return "yaml:" + strings.TrimSpace(strings.ReplaceAll(set[:eqIdx], ".", "::")) + ": " + strings.TrimSpace(set[eqIdx+1:])
+}