DataDog · dineshg13 · Feb 7, 2026
@@ -1,16 +1,25 @@
 # Unless explicitly stated otherwise all files in this repository are licensed
 # under the Apache 2.0 License.
 #
-FROM golang:1.22
-
+# Multi-stage build for the calendar-dd gRPC server.
+# Stage 1: Build the Go binary.
+FROM golang:1.22 AS builder
 
 WORKDIR /app
 COPY calendar-dd calendar/
 COPY protos protos/
 
 WORKDIR /app/calendar
 RUN go mod download
+RUN CGO_ENABLED=0 go build -o /calendar
+
+# Stage 2: Create a minimal runtime image.
+FROM gcr.io/distroless/static-debian12:nonroot
+
+COPY --from=builder /calendar /calendar
 
-RUN go build -o /calendar
+# Expose the gRPC port.
+EXPOSE 9090
 
+# Run as non-root user (provided by distroless:nonroot).
 CMD [ "/calendar" ]
@@ -1,16 +1,25 @@
 # Unless explicitly stated otherwise all files in this repository are licensed
 # under the Apache 2.0 License.
 #
-FROM golang:1.22
-
+# Multi-stage build for the calendar-otel gRPC server.
+# Stage 1: Build the Go binary.
+FROM golang:1.22 AS builder
 
 WORKDIR /app
 COPY calendar-otel calendar/
 COPY protos protos/
 
 WORKDIR /app/calendar
 RUN go mod download
+RUN CGO_ENABLED=0 go build -o /calendar
+
+# Stage 2: Create a minimal runtime image.
+FROM gcr.io/distroless/static-debian12:nonroot
+
+COPY --from=builder /calendar /calendar
 
-RUN go build -o /calendar
+# Expose the gRPC port.
+EXPOSE 9090
 
+# Run as non-root user (provided by distroless:nonroot).
 CMD [ "/calendar" ]
@@ -1,15 +1,46 @@
-# Calendar GRPC server
+# Calendar gRPC Server
 
 Generate proto files using script `generate.sh`
 
-`calendar-dd` is instrumented with DD tracer.
-`calendar-otel` is instrumented with Otel tracer.
+`calendar-dd` is instrumented with the DD tracer (`dd-trace-go` OTel provider).
+`calendar-otel` is instrumented with the OTel SDK tracer (OTLP exporter to DD Agent).
 
-Both the servers have implemented [health grpc](https://github.com/grpc-ecosystem/grpc-health-probe)
+Both servers implement [gRPC health checking](https://github.com/grpc-ecosystem/grpc-health-probe).
 
-## kubernetes
+## gRPC Instrumentation
 
-***Build***
+Both variants use `otelgrpc.NewServerHandler()` (stats handler) for gRPC tracing,
+which is the recommended approach as of otelgrpc v0.49.0+. The deprecated
+`UnaryServerInterceptor`/`StreamServerInterceptor` pattern has been replaced.
+
+The stats handler automatically creates spans with semantic convention attributes:
+- `rpc.system` = "grpc"
+- `rpc.service` = the gRPC service name
+- `rpc.method` = the gRPC method name
+- `rpc.grpc.status_code` = the gRPC status code
+
+These attributes map to Datadog APM resource names when ingested via OTLP.
+
+## OpenCensus Bridge (Deprecated)
+
+The `calendar-client` and `calendar-otel` variants use the OpenCensus gRPC plugin
+(`go.opencensus.io/plugin/ocgrpc`) for collecting gRPC metrics (e.g.,
+`grpc.io/client/roundtrip_latency`, `grpc.io/server/server_latency`). These metrics
+are bridged to OTel via `go.opentelemetry.io/otel/bridge/opencensus` and exported
+through the OTLP pipeline to the Datadog Agent.
+
+**OpenCensus is archived (deprecated since 2023).** The recommended migration path is:
+
+1. Replace `ocgrpc.ServerHandler` / `ocgrpc.ClientHandler` with
+   `otelgrpc.NewServerHandler()` / `otelgrpc.NewClientHandler()`, which provide
+   built-in metrics collection starting with otelgrpc v0.49.0+.
+2. Remove the `go.opencensus.io` and `go.opentelemetry.io/otel/bridge/opencensus`
+   dependencies.
+3. See: https://opentelemetry.io/docs/migration/opencensus/
+
+## Kubernetes
+
+**Build**
 
 calendar-dd
 
@@ -23,7 +54,7 @@ calendar-otel
 docker build --file Dockerfile.calendar.go.otel --tag otel-demo:calendar-go-otel .
 ```
 
-***Deploy***
+**Deploy**
 
 Install calendar-dd
 
@@ -39,13 +70,22 @@ helm install -n otel-ingest calendar-go-otel-ingest ./calendar-otel/k8s/ --set n
 ```
 
 
-# Calendar client
+# Calendar Client
 
 When you have the calendar server running locally, you can use calendar-client to send gRPC requests to the server.
 
 ```
-cd calendar-client 
+cd calendar-client
 go run main.go
 ```
 
-The client is instrumented with [OpenCensus gRPC plug-in](https://pkg.go.dev/go.opencensus.io/plugin/ocgrpc) which automatically collects gRPC metrics. It then uses the [OpenCensus Bridge from OpenTelemetry](https://github.com/open-telemetry/opentelemetry-go/tree/main/bridge/opencensus) and [OTLP exporter](https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlpmetric) to export the metrics in OTLP format. 
+The client is instrumented with [OpenCensus gRPC plug-in](https://pkg.go.dev/go.opencensus.io/plugin/ocgrpc) which automatically collects gRPC metrics. It then uses the [OpenCensus Bridge from OpenTelemetry](https://github.com/open-telemetry/opentelemetry-go/tree/main/bridge/opencensus) and [OTLP exporter](https://github.com/open-telemetry/opentelemetry-go/tree/main/exporters/otlp/otlpmetric) to export the metrics in OTLP format.
+
+## TLS Configuration
+
+Both servers currently use insecure connections for simplicity. For production deployments:
+
+1. Generate TLS certificates (e.g., via cert-manager in Kubernetes).
+2. Use `grpc.Creds(credentials.NewTLS(tlsConfig))` server option.
+3. Use `grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig))` client option.
+4. See: https://grpc.io/docs/guides/auth/#with-server-authentication-ssltls
@@ -1,38 +1,36 @@
 module github.com/DataDog/opentelemetry-examples/apps/rpc/calendar-client
 
-go 1.20
+go 1.22.0
 
 replace github.com/DataDog/opentelemetry-examples/apps/rpc/protos => ../protos/
 
 require (
 	github.com/DataDog/opentelemetry-examples/apps/rpc/protos v0.0.0-00010101000000-000000000000
 	go.opencensus.io v0.24.0
-	go.opentelemetry.io/otel v1.16.0
-	go.opentelemetry.io/otel/bridge/opencensus v0.39.0
-	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.39.0
-	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v0.39.0
-	go.opentelemetry.io/otel/sdk/metric v0.39.0
-	google.golang.org/grpc v1.57.1
+	go.opentelemetry.io/otel v1.34.0
+	go.opentelemetry.io/otel/bridge/opencensus v1.34.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.34.0
+	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.34.0
+	go.opentelemetry.io/otel/sdk/metric v1.34.0
+	google.golang.org/grpc v1.69.4
 )
 
 require (
-	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
-	github.com/go-logr/logr v1.2.4 // indirect
+	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
-	github.com/golang/protobuf v1.5.3 // indirect
-	github.com/grpc-ecosystem/grpc-gateway/v2 v2.17.1 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/internal/retry v1.16.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.39.0 // indirect
-	go.opentelemetry.io/otel/metric v1.16.0 // indirect
-	go.opentelemetry.io/otel/sdk v1.16.0 // indirect
-	go.opentelemetry.io/otel/trace v1.16.0 // indirect
-	go.opentelemetry.io/proto/otlp v1.0.0 // indirect
-	golang.org/x/net v0.17.0 // indirect
-	golang.org/x/sys v0.13.0 // indirect
-	golang.org/x/text v0.13.0 // indirect
-	google.golang.org/genproto v0.0.0-20230822172742-b8732ec3820d // indirect
-	google.golang.org/genproto/googleapis/api v0.0.0-20230822172742-b8732ec3820d // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20230822172742-b8732ec3820d // indirect
-	google.golang.org/protobuf v1.31.0 // indirect
+	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.25.1 // indirect
+	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
+	go.opentelemetry.io/otel/metric v1.34.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.34.0 // indirect
+	go.opentelemetry.io/otel/trace v1.34.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.5.0 // indirect
+	golang.org/x/net v0.34.0 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/text v0.21.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20250115164207-1a7da9e5054f // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250115164207-1a7da9e5054f // indirect
+	google.golang.org/protobuf v1.36.3 // indirect
 )