Add Grafana Loki example (#30)

README.md

@@ -107,7 +107,8 @@ Observe the logs
 Note that not all log entries will immediately be written to the `otlp-logs.log` file. The collector will flush to the disk eventually. The flush will be forced if the collector receives a kill signal.
 
 ## Examples
-[HTTP Server with trace context propagation](./examples/trace-context)
+* [HTTP Server with trace context propagation](./examples/trace-context)
+* [Sending logs to Grafana Loki](./examples/grafana-loki)
 
 ## Options
 

examples/grafana-loki/README.md

@@ -0,0 +1,34 @@
+# Sending logs to Grafana Loki
+
+```mermaid
+graph LR;
+    pino["Pino Opentelemetry Transport"]
+    otel["OTEL Collector"]
+    loki["Loki"]
+    grafana["Grafana"]
+    pino-->otel;
+    otel-->loki;
+    loki-->grafana;
+```
+
+## Running the example
+
+### Local infrastructure
+
+Run the required infra locally with
+`docker compose up`
+
+It will boot [Grafana](https://grafana.com/docs/grafana/latest/), [Loki](https://grafana.com/docs/loki/latest/) and an [Opentelemetry Collector](https://opentelemetry.io/docs/collector/).
+
+Loki ingester readiness can be checked at
+[http://localhost:3100/ready](http://localhost:3100/ready).
+
+The logs can be inspected in Grafana UI at
+[http://localhost:3000/explore](http://localhost:3000/explore).
+
+[This article](https://grafana.com/docs/opentelemetry/visualization/loki-data/) explains how to inspect OTLP data in the Grafana UI.
+
+### Generating logs
+Run the [trace-context](../trace-context) example, but skip the `docker compose up` part
+
+

examples/grafana-loki/docker-compose.yaml

@@ -0,0 +1,58 @@
+version: "3"
+
+networks:
+  loki:
+
+services:
+  loki:
+    image: grafana/loki:2.9.0
+    ports:
+      - "3100:3100"
+    command: -config.file=/etc/loki/local-config.yaml
+    networks:
+      - loki
+
+  grafana:
+    environment:
+      - GF_PATHS_PROVISIONING=/etc/grafana/provisioning
+      - GF_AUTH_ANONYMOUS_ENABLED=true
+      - GF_AUTH_ANONYMOUS_ORG_ROLE=Admin
+    entrypoint:
+      - sh
+      - -euc
+      - |
+        mkdir -p /etc/grafana/provisioning/datasources
+        cat <<EOF > /etc/grafana/provisioning/datasources/ds.yaml
+        apiVersion: 1
+        datasources:
+        - name: Loki
+          type: loki
+          access: proxy
+          orgId: 1
+          url: http://loki:3100
+          basicAuth: false
+          isDefault: true
+          version: 1
+          editable: false
+        EOF
+        /run.sh
+    image: grafana/grafana:latest
+    ports:
+      - "3000:3000"
+    networks:
+      - loki
+    depends_on:
+      - loki
+
+  otel-collector:
+    image: otel/opentelemetry-collector-contrib:latest
+    command: ["--config=/etc/otel-collector-config.yaml"]
+    volumes:
+      - ./otel-collector-config.yaml:/etc/otel-collector-config.yaml
+      - /tmp/test-logs:/etc/test-logs
+    ports:
+      - "4317:4317"   # OTLP gRPC receiver
+    networks:
+      - loki
+    depends_on:
+      - loki

examples/grafana-loki/otel-collector-config.yaml

@@ -0,0 +1,19 @@
+receivers:
+  otlp:
+    protocols:
+      grpc:
+
+exporters:
+  loki:
+    endpoint: http://loki:3100/loki/api/v1/push
+
+processors:
+  batch:
+
+service:
+  pipelines:
+    logs:
+      receivers: [otlp]
+      processors: []
+      exporters: [loki]
+