add httpcheck receiver example (open-telemetry#1162)

* add httpcheck receiver example

This PR adds the httpcheck receiver to the demo to produce a synthetic
check against the frontendproxy endpoint.

Signed-off-by: Alex Boten <aboten@lightstep.com>

* add changelog

Signed-off-by: Alex Boten <aboten@lightstep.com>

---------

Signed-off-by: Alex Boten <aboten@lightstep.com>
Co-authored-by: Austin Parker <austin@ap2.io>

CHANGELOG.md

@@ -21,6 +21,8 @@ release.
   ([#1146](https://github.com/open-telemetry/opentelemetry-demo/pull/1146))
 * [prometheus] Enabled support for the OTLP write receiver
   ([#1149](https://github.com/open-telemetry/opentelemetry-demo/pull/1149))
+* [otelcol] add httpcheck receiver for synthetic check of frontendproxy
+  ([#1162](https://github.com/open-telemetry/opentelemetry-demo/pull/1162))
 
 ## 1.5.0
 

docker-compose.yml

@@ -669,6 +669,8 @@ services:
     depends_on:
       - jaeger
     logging: *logging
+    environment:
+      - ENVOY_PORT
 
   # Prometheus
   prometheus:

src/otelcollector/otelcol-config.yml

@@ -11,6 +11,9 @@ receivers:
           allowed_origins:
             - "http://*"
             - "https://*"
+  httpcheck/frontendproxy:
+    targets:
+      - endpoint: http://frontendproxy:${env:ENVOY_PORT}
 
 exporters:
   logging:
@@ -43,7 +46,7 @@ service:
       processors: [batch]
       exporters: [logging, spanmetrics]
     metrics:
-      receivers: [otlp, spanmetrics]
+      receivers: [httpcheck/frontendproxy, otlp, spanmetrics]
       processors: [filter/ottl, transform, batch]
       exporters: [logging]
     logs: