feat(outputs.opentelemetry): Support dot-separated OpenTelemetry metric names by mchrome · Pull Request #18680 · influxdata/telegraf

mchrome · 2026-04-09T05:35:32Z

Summary

This is a reopened PR #18252 which was closed due to inactivity. I've personally reviewed the changes in this one and can answer any questions or make changes which may be requested during the review process.

Summary from original PR:

This PR adds support for preserving dot-separated OpenTelemetry metric names in the OpenTelemetry output plugin, addressing issue #18251.

Added a new metric_name_format configuration option that allows users to choose between:

prometheus (default): Converts dots to underscores - maintains backward compatibility
otel: Preserves dot-separated names - enables OpenTelemetry semantic conventions

This PR adds support for preserving dot-separated OpenTelemetry metric names in the OpenTelemetry output plugin

Checklist

No AI generated code was used in this PR
AI generated code used in this PR follows the InfluxData Policy on AI-Generated Code Contributions

Related issues

resolves #18251

…ic names

telegraf-tiger · 2026-04-09T05:54:03Z

Download PR build artifacts for linux_amd64.tar.gz, darwin_arm64.tar.gz, and windows_amd64.zip.
Downloads for additional architectures and packages are available below.

☺️ This pull request doesn't significantly change the Telegraf binary size (less than 1%)

📦 Click here to get additional PR build artifacts

Artifact URLs

. DEB	. RPM	. TAR . GZ	. ZIP
amd64.deb	aarch64.rpm	darwin_amd64.tar.gz	windows_amd64.zip
arm64.deb	armel.rpm	darwin_arm64.tar.gz	windows_arm64.zip
armel.deb	armv6hl.rpm	freebsd_amd64.tar.gz	windows_i386.zip
armhf.deb	i386.rpm	freebsd_armv7.tar.gz
i386.deb	ppc64le.rpm	freebsd_i386.tar.gz
mips.deb	riscv64.rpm	linux_amd64.tar.gz
mipsel.deb	s390x.rpm	linux_arm64.tar.gz
ppc64el.deb	x86_64.rpm	linux_armel.tar.gz
riscv64.deb		linux_armhf.tar.gz
s390x.deb		linux_i386.tar.gz
		linux_mips.tar.gz
		linux_mipsel.tar.gz
		linux_ppc64le.tar.gz
		linux_riscv64.tar.gz
		linux_s390x.tar.gz

mchrome · 2026-04-13T10:35:22Z

@srebhan Could you take a look at this PR?

srebhan

Thanks @mchrome! I do have some comments...

srebhan · 2026-04-17T09:12:39Z

+	if o.MetricNameFormat == "" {
+		o.MetricNameFormat = defaultMetricNameFormat
+	}
+	switch o.MetricNameFormat {
+	case "prometheus", "otel":


Suggested change

if o.MetricNameFormat == "" {

o.MetricNameFormat = defaultMetricNameFormat

}

switch o.MetricNameFormat {

case "prometheus", "otel":

switch o.MetricNameFormat {

case "":

o.MetricNameFormat = "prometheus"

case "prometheus", "otel":

srebhan · 2026-04-17T09:15:52Z

+	defaultServiceAddress   = "localhost:4317"
+	defaultTimeout          = config.Duration(5 * time.Second)
+	defaultCompression      = "gzip"
+	defaultMetricNameFormat = "prometheus"


Please do not add constants for this! There is no benefit really!

srebhan · 2026-04-17T09:16:03Z

+			ServiceAddress:   defaultServiceAddress,
+			Timeout:          defaultTimeout,
+			Compression:      defaultCompression,
+			MetricNameFormat: defaultMetricNameFormat,


This will be set in Init()!

srebhan · 2026-04-17T09:18:45Z

+	// Only check metadata if it exists (for tests that provide headers)
 	ctxMetadata, ok := metadata.FromIncomingContext(ctx)
-	require.Equal(m.t, []string{"header1"}, ctxMetadata.Get("test"))
-	require.True(m.t, ok)
+	if ok {
+		if testHeader := ctxMetadata.Get("test"); len(testHeader) > 0 {
+			require.Equal(m.t, []string{"header1"}, testHeader)
+		}
+	}


Why is this change necessary?

srebhan · 2026-04-17T09:18:58Z

 	return pmetricotlp.NewExportResponse(), nil
 }
+
+func TestOpenTelemetryMetricNameFormatPrometheus(t *testing.T) {


How about

Suggested change

func TestOpenTelemetryMetricNameFormatPrometheus(t *testing.T) {

func TestNameFormatPrometheus(t *testing.T) {

srebhan · 2026-04-17T09:22:04Z

+	got := m.GotMetrics()
+	require.Equal(t, 1, got.ResourceMetrics().Len())
+	require.Equal(t, 1, got.ResourceMetrics().At(0).ScopeMetrics().Len())
+	require.Equal(t, 1, got.ResourceMetrics().At(0).ScopeMetrics().At(0).Metrics().Len())
+	require.Equal(t, "http_server_duration", got.ResourceMetrics().At(0).ScopeMetrics().At(0).Metrics().At(0).Name())


All other tests compare the JSON representation of the metric. Can we please stick to this? Same for the other tests below.

srebhan · 2026-04-17T09:23:13Z

+		metricName := o.transformMetricName(metric.Name())
+		err := batch.AddPoint(metricName, metric.Tags(), metric.Fields(), metric.Time(), vType)


Please fold the code in here

Suggested change

metricName := o.transformMetricName(metric.Name())

err := batch.AddPoint(metricName, metric.Tags(), metric.Fields(), metric.Time(), vType)

// Transform the metric name if required

name := metric.Name()

switch o.MetricNameFormat

case "prometheus":

// Prometheus doesn't like dots

name = strings.ReplaceAll(name, ".", "_")

}

err := batch.AddPoint(name, metric.Tags(), metric.Fields(), metric.Time(), vType)

srebhan · 2026-04-17T09:24:44Z

+	if o.MetricNameFormat == "" {
+		o.MetricNameFormat = defaultMetricNameFormat
+	}


Doesn't this change the existing behavior? In the existing code we do not replace anything in the metric name, do we?

srebhan · 2026-04-17T09:26:30Z

+  ## Override the default (prometheus) metric name format
+  ## prometheus: converts dots to underscores (default, Prometheus-compatible)
+  ## otel: preserves dot-separated names (OpenTelemetry semantic conventions)


Please be brief, defaults are documented in the option!

Suggested change

## Override the default (prometheus) metric name format

## prometheus: converts dots to underscores (default, Prometheus-compatible)

## otel: preserves dot-separated names (OpenTelemetry semantic conventions)

## Transform metric names according to the given format, available options:

## prometheus -- converts dots to underscores

## otel -- keep metric names as-is

srebhan · 2026-04-17T09:27:53Z

+  ## Override the default (prometheus) metric name format
+  ## prometheus: converts dots to underscores (default, Prometheus-compatible)
+  ## otel: preserves dot-separated names (OpenTelemetry semantic conventions)
+  # metric_name_format = "prometheus"


In the code before this PR, I don't see where we replace dots with underscores, so you are changing the default behavior and break everyone using this plugin. Am I missing anything?

madelyngamble2 added 5 commits April 9, 2026 01:29

feat(outputs.opentelemetry): Support dot-separated OpenTelemetry metr…

15a3124

…ic names

fix(outputs.opentelemetry): Fix markdown line length linting issues

99c118f

fix(outputs.opentelemetry): Fix gofmt formatting issues

b72ea8a

fix: align const block formatting to pass gofmt check

8b0a786

fix: align struct initialization spacing in test file to pass gofmt

45d4f24

telegraf-tiger bot added feat Improvement on an existing feature such as adding a new setting/mode to an existing plugin plugin/output 1. Request for new output plugins 2. Issues/PRs that are related to out plugins labels Apr 9, 2026

srebhan reviewed Apr 17, 2026

View reviewed changes

srebhan self-assigned this Apr 17, 2026

	func TestOpenTelemetryMetricNameFormatPrometheus(t *testing.T) {
	func TestNameFormatPrometheus(t *testing.T) {

		metricName := o.transformMetricName(metric.Name())
		err := batch.AddPoint(metricName, metric.Tags(), metric.Fields(), metric.Time(), vType)

-		metricName := o.transformMetricName(metric.Name())
-		err := batch.AddPoint(metricName, metric.Tags(), metric.Fields(), metric.Time(), vType)
+	// Transform the metric name if required
+	name := metric.Name()
+	switch o.MetricNameFormat
+	case "prometheus":
+		// Prometheus doesn't like dots
+		name = strings.ReplaceAll(name, ".", "_")
+	}
+	err := batch.AddPoint(name, metric.Tags(), metric.Fields(), metric.Time(), vType)

Conversation

mchrome commented Apr 9, 2026

Summary

Checklist

Related issues

Uh oh!

telegraf-tiger bot commented Apr 9, 2026

Artifact URLs

Uh oh!

mchrome commented Apr 13, 2026

Uh oh!

srebhan left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants