Added Readme file for otel (#3992)

Added README file for otel.
README is dynamically re-generated when dependencies are changed.

mage otelReadme
will parse dependencies and regenerate output file.

command is also part of mage update or mage check

internal/pkg/otel/README.md

@@ -0,0 +1,58 @@
+# Elastic Distribution for OpenTelemetry Collector
+
+This is an Elastic supported distribution of the [OpenTelemetry Collector](https://github.com/open-telemetry/opentelemetry-collector).
+
+## Running the Elastic Distribution for OpenTelemetry Collector
+
+To run the Elastic Distribution for OpenTelemetry Collector you can use Elastic-Agent binary downloaded for your OS and architecture. 
+Running command 
+
+```bash
+./elastic-agent -c otel.yml run
+```
+
+from unpacked Elastic Agent package will run Elastic-Agent as an OpenTelemetry Collector. The `-c` flag needs to point to [OpenTelemetry Collector Configuration file](https://opentelemetry.io/docs/collector/configuration/) named `otel`, `otlp` or `otelcol`.
+Both `yaml` and `yml` suffixes are supported. 
+
+> In case this condition is not met, Elastic Agent will run in its default mode and will not behave as OpenTelemetry Collector.
+
+Note that `validate` subcommand and [feature gates](https://github.com/open-telemetry/opentelemetry-collector/blob/main/featuregate/README.md#controlling-gates) are not supported yet.
+
+## Components
+
+This section provides a summary of components included in the Elastic Distribution for OpenTelemetry Collector.
+
+
+### Receivers
+
+| Component | Version |
+|---|---|
+| filelogreceiver | v0.89.0|
+| otlpreceiver | v0.89.0|
+
+
+
+
+### Exporters
+
+| Component | Version |
+|---|---|
+| fileexporter | v0.89.0|
+| debugexporter | v0.89.0|
+| otlpexporter | v0.89.0|
+
+
+
+
+### Processors
+
+| Component | Version |
+|---|---|
+| attributesprocessor | v0.89.0|
+| resourceprocessor | v0.89.0|
+| transformprocessor | v0.89.0|
+| batchprocessor | v0.89.0|
+| memorylimiterprocessor | v0.89.0|
+
+
+

internal/pkg/otel/templates/README.md.tmpl

@@ -0,0 +1,59 @@
+# Elastic Distribution for OpenTelemetry Collector
+
+This is an Elastic supported distribution of the [OpenTelemetry Collector](https://github.com/open-telemetry/opentelemetry-collector).
+
+## Running the Elastic Distribution for OpenTelemetry Collector
+
+To run the Elastic Distribution for OpenTelemetry Collector you can use Elastic-Agent binary downloaded for your OS and architecture. 
+Running command 
+
+```bash
+./elastic-agent -c otel.yml run
+```
+
+from unpacked Elastic Agent package will run Elastic-Agent as an OpenTelemetry Collector. The `-c` flag needs to point to [OpenTelemetry Collector Configuration file](https://opentelemetry.io/docs/collector/configuration/) named `otel`, `otlp` or `otelcol`.
+Both `yaml` and `yml` suffixes are supported. 
+
+> In case this condition is not met, Elastic Agent will run in its default mode and will not behave as OpenTelemetry Collector.
+
+Note that `validate` subcommand and [feature gates](https://github.com/open-telemetry/opentelemetry-collector/blob/main/featuregate/README.md#controlling-gates) are not supported yet.
+
+## Components
+
+This section provides a summary of components included in the Elastic Distribution for OpenTelemetry Collector.
+
+{{ if .Receivers }}
+### Receivers
+
+| Component | Version |
+|---|---|
+{{ range .Receivers }}| {{ .Name }} | {{ .Version -}} |
+{{ end }}
+{{ end }}
+
+{{ if .Exporters }}
+### Exporters
+
+| Component | Version |
+|---|---|
+{{ range .Exporters }}| {{ .Name }} | {{ .Version -}} |
+{{ end }}
+{{ end }}
+
+{{ if .Processors }}
+### Processors
+
+| Component | Version |
+|---|---|
+{{ range .Processors }}| {{ .Name }} | {{ .Version -}} |
+{{ end }}
+{{ end }}
+
+{{ if .Extensions }}
+### Extensions
+
+| Component | Version |
+|---|---|
+{{ range .Extensions }}| {{ .Name }} | {{ .Version -}} |
+{{ end }}
+{{ end }}

magefile.go

@@ -12,6 +12,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"html/template"
 	"log"
 	"os"
 	"os/exec"
@@ -120,6 +121,9 @@ type Cloud mg.Namespace
 // Integration namespace contains tasks related to operating and running integration tests.
 type Integration mg.Namespace
 
+// Otel namespace contains Open Telemetry related tasks.
+type Otel mg.Namespace
+
 func CheckNoChanges() error {
 	fmt.Println(">> fmt - go run")
 	err := sh.RunV("go", "mod", "tidy", "-v")
@@ -550,7 +554,7 @@ func commitID() string {
 
 // Update is an alias for executing control protocol, configs, and specs.
 func Update() {
-	mg.SerialDeps(Config, BuildPGP, BuildFleetCfg)
+	mg.SerialDeps(Config, BuildPGP, BuildFleetCfg, Otel.Readme)
 }
 
 // CrossBuild cross-builds the beat for all target platforms.
@@ -2243,3 +2247,118 @@ func hasCleanOnExit() bool {
 	b, _ := strconv.ParseBool(clean)
 	return b
 }
+
+type dependency struct {
+	Name    string
+	Version string
+}
+
+type dependencies struct {
+	Receivers  []dependency
+	Exporters  []dependency
+	Processors []dependency
+	Extensions []dependency
+}
+
+func (d dependency) Clean(sep string) dependency {
+	cleanFn := func(dep, sep string) string {
+		chunks := strings.SplitN(dep, sep, 2)
+		if len(chunks) == 2 {
+			return chunks[1]
+		}
+
+		return dep
+	}
+
+	return dependency{
+		Name:    cleanFn(d.Name, sep),
+		Version: d.Version,
+	}
+}
+
+func (Otel) Readme() error {
+	fmt.Println(">> Building internal/pkg/otel/README.md")
+
+	readmeTmpl := filepath.Join("internal", "pkg", "otel", "templates", "README.md.tmpl")
+	readmeOut := filepath.Join("internal", "pkg", "otel", "README.md")
+
+	// read README template
+	tmpl, err := template.ParseFiles(readmeTmpl)
+	if err != nil {
+		return fmt.Errorf("failed to parse README template: %w", err)
+	}
+
+	data, err := getOtelDependencies()
+	if err != nil {
+		return fmt.Errorf("Failed to get OTel dependencies: %w", err)
+	}
+
+	// resolve template
+	out, err := os.OpenFile(readmeOut, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+	if err != nil {
+		return fmt.Errorf("failed to open file %s: %w", readmeOut, err)
+	}
+	defer out.Close()
+
+	return tmpl.Execute(out, data)
+}
+
+func getOtelDependencies() (*dependencies, error) {
+	// read go.mod
+	readFile, err := os.Open("go.mod")
+	if err != nil {
+		return nil, err
+	}
+	defer readFile.Close()
+
+	scanner := bufio.NewScanner(readFile)
+
+	scanner.Split(bufio.ScanLines)
+	var receivers, extensions, exporters, processors []dependency
+	// process imports
+	for scanner.Scan() {
+		l := strings.TrimSpace(scanner.Text())
+		// is otel
+		if !strings.Contains(l, "go.opentelemetry.io/") &&
+			!strings.Contains(l, "github.com/open-telemetry/") {
+			continue
+		}
+
+		if strings.Contains(l, "// indirect") {
+			continue
+		}
+
+		parseLine := func(line string) (dependency, error) {
+			chunks := strings.SplitN(line, " ", 2)
+			if len(chunks) != 2 {
+				return dependency{}, fmt.Errorf("incorrect format for line %q", line)
+			}
+			return dependency{
+				Name:    chunks[0],
+				Version: chunks[1],
+			}, nil
+		}
+
+		d, err := parseLine(l)
+		if err != nil {
+			return nil, err
+		}
+
+		if strings.Contains(l, "/receiver/") {
+			receivers = append(receivers, d.Clean("/receiver/"))
+		} else if strings.Contains(l, "/processor/") {
+			processors = append(processors, d.Clean("/processor/"))
+		} else if strings.Contains(l, "/exporter/") {
+			exporters = append(exporters, d.Clean("/exporter/"))
+		} else if strings.Contains(l, "/extension/") {
+			extensions = append(extensions, d.Clean("/extension/"))
+		}
+	}
+
+	return &dependencies{
+		Receivers:  receivers,
+		Exporters:  exporters,
+		Processors: processors,
+		Extensions: extensions,
+	}, nil
+}