LCORE-1802: Add OpenTelemetry environment variables to docker-compose

Add OpenTelemetry OTLP exporter configuration environment variables to docker-compose files
with safe defaults that keep tracing disabled until explicitly enabled.

Variables added use `${VAR_NAME:-default}` pattern for flexible configuration:

1. **`OTEL_EXPORTER_OTLP_ENDPOINT`** - OTLP collector endpoint URL (default: empty)
2. **`OTEL_EXPORTER_OTLP_PROTOCOL`** - Export protocol, e.g. `http/protobuf` or `grpc` (default: empty)
3. **`OTEL_SERVICE_NAME`** - Service identifier in traces (default: empty)
4. **`OTEL_SDK_DISABLED`** - Enable/disable tracing (default: `true` - **tracing OFF**)

Signed-off-by: Anik Bhattacharjee <anbhatta@redhat.com>

Author: anik120

docker-compose-library.yaml

@@ -61,6 +61,11 @@ services:
       - FAISS_VECTOR_STORE_ID=${FAISS_VECTOR_STORE_ID:-}
       # Prevent HuggingFace Hub update checks (HTTP 429 rate-limiting in CI from parallel jobs).
       - HF_HUB_OFFLINE=1
+      # OpenTelemetry configuration (tracing disabled by default)
+      - OTEL_EXPORTER_OTLP_ENDPOINT=${OTEL_EXPORTER_OTLP_ENDPOINT:-}
+      - OTEL_EXPORTER_OTLP_PROTOCOL=${OTEL_EXPORTER_OTLP_PROTOCOL:-}
+      - OTEL_SERVICE_NAME=${OTEL_SERVICE_NAME:-}
+      - OTEL_SDK_DISABLED=${OTEL_SDK_DISABLED:-true}
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8080/liveness"]
       interval: 10s   # how often to run the check

docker-compose.yaml

@@ -101,6 +101,11 @@ services:
       # Substituted in mounted lightspeed-stack.yaml (llama_stack.url); GitHub Actions sets via vars
       - E2E_LLAMA_HOSTNAME=${E2E_LLAMA_HOSTNAME:-llama-stack}
       - E2E_LLAMA_PORT=${E2E_LLAMA_PORT:-8321}
+      # OpenTelemetry configuration (tracing disabled by default)
+      - OTEL_EXPORTER_OTLP_ENDPOINT=${OTEL_EXPORTER_OTLP_ENDPOINT:-}
+      - OTEL_EXPORTER_OTLP_PROTOCOL=${OTEL_EXPORTER_OTLP_PROTOCOL:-}
+      - OTEL_SERVICE_NAME=${OTEL_SERVICE_NAME:-}
+      - OTEL_SDK_DISABLED=${OTEL_SDK_DISABLED:-true}
     depends_on:
         llama-stack:
           condition: service_healthy