openfaas · welteki · Jun 2, 2025
diff --git a/README.md b/README.md
@@ -245,6 +245,18 @@ func Handle(w http.ResponseWriter, r *http.Request) {
 }
 ```
 
+### OpenTelemetry
+
+The `golang-otel` template as a variant of the `golang-middleware` template with built-in support for [OpenTelemetry](https://opentelemetry.io/) traces. It allow you to collect traces for HTTP requests by default and makes it easy to extend the function with your own spans.
+
+Create a new function with OpenTelemetry support by running:
+
+```sh
+faas new --lang golang-otel <fn-name>
+```
+
+See the [OpenFaaS docs](https://docs.openfaas.com/languages/go/#opentelemetry-instrumentation) for information on how to use the template.
+
 ## 2.0 golang-http
 
 This template provides additional context and control over the HTTP response from your function.

diff --git a/template/golang-otel/.gitignore b/template/golang-otel/.gitignore
@@ -0,0 +1 @@
+/handler
diff --git a/template/golang-otel/Dockerfile b/template/golang-otel/Dockerfile
@@ -0,0 +1,60 @@
+FROM --platform=${TARGETPLATFORM:-linux/amd64} ghcr.io/openfaas/of-watchdog:0.10.9 AS watchdog
+FROM --platform=${BUILDPLATFORM:-linux/amd64} golang:1.23-alpine AS build
+
+ARG TARGETPLATFORM
+ARG BUILDPLATFORM
+ARG TARGETOS
+ARG TARGETARCH
+
+RUN apk --no-cache add git
+
+COPY --from=watchdog /fwatchdog /usr/bin/fwatchdog
+RUN chmod +x /usr/bin/fwatchdog
+
+RUN mkdir -p /go/src/handler
+WORKDIR /go/src/handler
+COPY . .
+
+ARG GO111MODULE="on"
+ARG GOPROXY=""
+ARG GOFLAGS=""
+ARG CGO_ENABLED=0
+ENV CGO_ENABLED=${CGO_ENABLED}
+
+# Run a gofmt and exclude all vendored code.
+RUN test -z "$(gofmt -l $(find . -type f -name '*.go' -not -path "./vendor/*" -not -path "./function/vendor/*"))" || { echo "Run \"gofmt -s -w\" on your Golang code"; exit 1; }
+
+WORKDIR /go/src/handler/function
+RUN mkdir -p /go/src/handler/function/static
+
+RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go test ./... -cover
+
+WORKDIR /go/src/handler
+RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
+    go build --ldflags "-s -w" -o handler .
+
+FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.21.3 AS ship
+
+# Add non root user and certs
+RUN apk --no-cache add ca-certificates \
+    && addgroup -S app && adduser -S -g app app
+
+# Split instructions so that buildkit can run & cache
+# the previous command ahead of time.
+RUN mkdir -p /home/app \
+    && chown app /home/app
+
+WORKDIR /home/app
+
+COPY --from=build --chown=app /go/src/handler/handler           .
+COPY --from=build --chown=app /usr/bin/fwatchdog                .
+COPY --from=build --chown=app /go/src/handler/function/static   static
+
+USER app
+
+ENV fprocess="./handler"
+ENV mode="http"
+ENV upstream_url="http://127.0.0.1:8082"
+ENV prefix_logs="false"
+
+CMD ["./fwatchdog"]
diff --git a/template/golang-otel/function/go.mod b/template/golang-otel/function/go.mod
@@ -0,0 +1,3 @@
+module handler/function
+
+go 1.18
diff --git a/template/golang-otel/function/handler.go b/template/golang-otel/function/handler.go
@@ -0,0 +1,22 @@
+package function
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+)
+
+func Handle(w http.ResponseWriter, r *http.Request) {
+	var input []byte
+
+	if r.Body != nil {
+		defer r.Body.Close()
+
+		body, _ := io.ReadAll(r.Body)
+
+		input = body
+	}
+
+	w.WriteHeader(http.StatusOK)
+	fmt.Fprintf(w, "Body: %s", input)
+}
diff --git a/template/golang-otel/go.mod b/template/golang-otel/go.mod
@@ -0,0 +1,32 @@
+module handler
+
+go 1.23.0
+
+require (
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0
+	go.opentelemetry.io/otel v1.36.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.36.0
+	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.36.0
+	go.opentelemetry.io/otel/sdk v1.36.0
+	google.golang.org/grpc v1.72.1
+)
+
+require (
+	github.com/cenkalti/backoff/v5 v5.0.2 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.3 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.36.0 // indirect
+	go.opentelemetry.io/otel/metric v1.36.0 // indirect
+	go.opentelemetry.io/otel/trace v1.36.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.6.0 // indirect
+	golang.org/x/net v0.40.0 // indirect
+	golang.org/x/sys v0.33.0 // indirect
+	golang.org/x/text v0.25.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250519155744-55703ea1f237 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250519155744-55703ea1f237 // indirect
+	google.golang.org/protobuf v1.36.6 // indirect
+)
diff --git a/template/golang-otel/go.sum b/template/golang-otel/go.sum
@@ -0,0 +1,63 @@
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+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
+github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
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+github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
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+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
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+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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diff --git a/template/golang-otel/go.work b/template/golang-otel/go.work
@@ -0,0 +1,6 @@
+go 1.23.0
+
+use (
+	.
+	./function
+)
diff --git a/template/golang-otel/go.work.sum b/template/golang-otel/go.work.sum
@@ -0,0 +1,29 @@
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