Rebrand file configuration to declarative configuration (#512)

Co-authored-by: Trask Stalnaker <[email protected]>

Author: jack-berg

declarative-configuration/README.md

@@ -0,0 +1,22 @@
+# Declarative Configuration Example
+
+This example demonstrates how to use [declarative configuration](https://opentelemetry.io/docs/specs/otel/configuration/#declarative-configuration) to configure the OpenTelemetry SDK using a YAML configuration file as defined in [opentelemetry-configuration](https://github.com/open-telemetry/opentelemetry-configuration).
+
+The configuration file is located at [otel-sdk-config.yaml](./otel-sdk-config.yaml).
+
+# How to run
+
+## Prerequisites
+
+* Java 1.8
+
+## Run
+
+```shell script
+export OTEL_EXPERIMENTAL_CONFIG_FILE=$(pwd)/otel-sdk-config.yaml
+../gradlew run
+```
+
+Observe how data is printed to the console as configured in [otel-sdk-config.yaml](./otel-sdk-config.yaml).
+
+For use with the OpenTelemetry Java, see [Java Agent declarative configuration](../javaagent/README.md#declarative-configuration).

file-configuration/build.gradle.kts renamed to declarative-configuration/build.gradle.kts

@@ -3,7 +3,7 @@ plugins {
     id("application")
 }
 
-description = "OpenTelemetry Example for File Configuration"
+description = "OpenTelemetry Example for Declarative Configuration"
 val moduleName by extra { "io.opentelemetry.examples.fileconfig" }
 
 dependencies {

file-configuration/otel-sdk-config.yaml renamed to declarative-configuration/otel-sdk-config.yaml

@@ -1,9 +1,12 @@
 # See https://github.com/open-telemetry/opentelemetry-configuration for details on schema and examples
+
+# TODO: the current support file format is 0.3, but the opentelemetry-java errantly checks that it is 0.1. This will be fixed in 1.44.0.
 file_format: "0.1"
 
 resource:
   attributes:
-    service.name:  "file-configuration-example"
+    - name: service.name
+      value: file-configuration-example
 
 tracer_provider:
   processors:

file-configuration/src/main/java/io/opentelemetry/examples/fileconfig/Application.java renamed to declarative-configuration/src/main/java/io/opentelemetry/examples/fileconfig/Application.java

@@ -26,7 +26,8 @@ public final class Application {
 
   public static void main(String[] args) throws InterruptedException, IOException {
     // it is important to initialize your SDK as early as possible in your application's lifecycle
-    InputStream is = Files.newInputStream(Paths.get(System.getenv("OTEL_CONFIG_FILE")));
+    InputStream is =
+        Files.newInputStream(Paths.get(System.getenv("OTEL_EXPERIMENTAL_CONFIG_FILE")));
     OpenTelemetrySdk openTelemetrySdk = FileConfiguration.parseAndCreate(is);
 
     Tracer tracer = openTelemetrySdk.getTracer("io.opentelemetry.example");

file-configuration/README.md

@@ -45,14 +45,16 @@ curl http://localhost:8080/ping
 
 Watch for spans, metrics, and logs in the collector log output
 
-## File Configuration
+## Declarative Configuration
 
-By default, this example uses the [environment variable configuration schema](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md) to configure the SDK. However, it also includes [sdk-config.yaml](./sdk-config.yaml) which demonstrates how the file configuration scheme can be used instead. `sdk-config.yaml` extends the [opentelemetry-configuration sdk-config.yaml](https://github.com/open-telemetry/opentelemetry-configuration/blob/v0.3.0/examples/sdk-config.yaml) template, demonstrating:
+By default, this example uses the [environment variable configuration schema](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/configuration/sdk-environment-variables.md) to configure the SDK. However, it also includes [sdk-config.yaml](./sdk-config.yaml) which demonstrates how the [declarative configuration](https://opentelemetry.io/docs/specs/otel/configuration/#declarative-configuration) scheme can be used to configure the SDK based on a YAML configuration file instead. 
+
+`sdk-config.yaml` extends the [opentelemetry-configuration sdk-config.yaml](https://github.com/open-telemetry/opentelemetry-configuration/blob/v0.3.0/examples/sdk-config.yaml) template, demonstrating:
 
 - Configuration of instrumentation (see `.instrumentation.java`) 
 - Configuration of [rule based routing sampler](https://github.com/open-telemetry/opentelemetry-java-contrib/tree/main/samplers) (see `.tracer_provider.sampler.parent_based.root`)
 
-To use file configuration instead of the environment variable scheme, add the following before starting the application and collector:
+To use declarative configuration instead of the environment variable scheme, add the following before starting the application and collector:
 
 ```shell
 export OTEL_EXPERIMENTAL_CONFIG_FILE=/sdk-config.yaml

javaagent/README.md

@@ -45,7 +45,7 @@ develocity {
 rootProject.name = "opentelemetry-java-examples"
 include(
     ":opentelemetry-examples-autoconfigure",
-    ":opentelemetry-examples-file-configuration",
+    ":opentelemetry-examples-declarative-configuration",
     ":opentelemetry-examples-http",
     ":opentelemetry-examples-jaeger",
     ":opentelemetry-examples-javaagent",