add example for spring with declarative config

Author: zeitlinger

spring-declarative-configuration/oats/docker-compose.yml

@@ -5,7 +5,9 @@ services:
       context: ../
       dockerfile: oats/Dockerfile
     environment:
-      SPRING_OTEL_EXPORTER_OTLP_ENDPOINT: http://lgtm:4318
+      OTEL_TRACER_PROVIDER_PROCESSORS_0_BATCH_EXPORTER_OTLP_HTTP_ENDPOINT: http://lgtm:4318/v1/traces
+      OTEL_METER_PROVIDER_READERS_0_PERIODIC_EXPORTER_OTLP_HTTP_ENDPOINT: http://lgtm:4318/v1/metrics
+      OTEL_LOGGER_PROVIDER_PROCESSORS_0_BATCH_EXPORTER_OTLP_HTTP_ENDPOINT: http://lgtm:4318/v1/logs
     ports:
       - "8080:8080"
     healthcheck:

spring-declarative-configuration/src/main/resources/application.yaml

@@ -21,7 +21,7 @@ otel:
       - batch:
           exporter:
             otlp_http:
-              endpoint: ${OTEL_EXPORTER_OTLP_ENDPOINT:http://localhost:4318}/v1/traces
+              endpoint: http://localhost:4318/v1/traces
 
       # Configure a console exporter for exploring without a collector/backend
       - batch:
@@ -49,11 +49,11 @@ otel:
       - periodic:
           exporter:
             otlp_http:
-              endpoint: ${OTEL_EXPORTER_OTLP_ENDPOINT:http://localhost:4318}/v1/metrics
+              endpoint: http://localhost:4318/v1/metrics
 
   logger_provider:
     processors:
       - batch:
           exporter:
             otlp_http:
-              endpoint: ${OTEL_EXPORTER_OTLP_ENDPOINT:http://localhost:4318}/v1/logs
+              endpoint: http://localhost:4318/v1/logs