add configuration for otel collector

First round of trying to configure the collector.

- Added otel-collector to pender's docker compose, for the first tests.
When I get this working I'll look into adding it to Check.
- Added a otel-collector-config.example.yaml we can use to create the
otel-collector-config.yaml. And updated .gitignore so it does not track
the config.yaml one.

.gitignore

@@ -26,4 +26,5 @@ config/cookies.txt
 coverage
 .idea
 .byebug_history
-*.env
+*.env
+otel-collector-config.yaml

docker-compose.yml

@@ -57,3 +57,17 @@ services:
     environment:
       RAILS_ENV: development
       SERVER_PORT: 3200
+  otel-collector:
+    image: otel/opentelemetry-collector-contrib
+    volumes:
+      - ./otel-collector-config.yaml:/etc/otelcol-contrib/config.yaml
+    depends_on:
+      - pender
+    ports:
+      - 1888:1888 # pprof extension
+      - 8888:8888 # Prometheus metrics exposed by the Collector
+      - 8889:8889 # Prometheus exporter metrics
+      - 13133:13133 # health_check extension
+      - 4317:4317 # OTLP gRPC receiver
+      - 4318:4318 # OTLP http receiver
+      - 55679:55679 # zpages extension

otel-collector-config.example.yaml

@@ -0,0 +1,29 @@
+receivers:
+  prometheus:
+    config:
+      scrape_configs:
+        - job_name: "prometheus"
+          scrape_interval: 15s
+          static_configs:
+            - targets: ["0.0.0.0:3200"] 
+
+processors:
+  batch:
+
+exporters:
+  otlp/metrics:
+    endpoint: "api.honeycomb.io:443" # US instance
+    #endpoint: "api.eu1.honeycomb.io:443" # EU instance
+    headers:
+      "x-honeycomb-team": "<Honeycomb API KEY>"
+      "x-honeycomb-dataset": "pender"
+
+service:
+  # telemetry:
+  #   logs:
+  #     level: "debug"
+  pipelines:
+    metrics:
+      receivers: [prometheus]
+      processors: []
+      exporters: [otlp/metrics]