add default values for env variable if not set (#1056)

*Issue #, if available:*

*Description of changes:*
add default values for env variable if not set for non lambda env


By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Author: shiyangy-xray

appsignals-tests/contract-tests/src/test/java/software/amazon/opentelemetry/appsignals/test/base/ContractTestBase.java

@@ -134,27 +134,18 @@ protected int getApplicationPort() {
   }
 
   protected Map<String, String> getApplicationEnvironmentVariables() {
-    return Map.of(
-        "JAVA_TOOL_OPTIONS",
-        "-javaagent:" + MOUNT_PATH,
-        "OTEL_METRIC_EXPORT_INTERVAL",
-        "100", // 100 ms
-        "OTEL_AWS_APPLICATION_SIGNALS_ENABLED",
-        "true",
-        "OTEL_AWS_APPLICATION_SIGNALS_RUNTIME_ENABLED",
-        isRuntimeEnabled(),
-        "OTEL_METRICS_EXPORTER",
-        "none",
-        "OTEL_BSP_SCHEDULE_DELAY",
-        "0", // Don't wait to export spans to the collector
-        "OTEL_AWS_APPLICATION_SIGNALS_EXPORTER_ENDPOINT",
-        COLLECTOR_HTTP_ENDPOINT,
-        "OTEL_EXPORTER_OTLP_TRACES_ENDPOINT",
-        COLLECTOR_HTTP_ENDPOINT,
-        "OTEL_RESOURCE_ATTRIBUTES",
-        getApplicationOtelResourceAttributes(),
-        "OTEL_EXPORTER_OTLP_PROTOCOL",
-        "grpc");
+    return Map.ofEntries(
+        Map.entry("JAVA_TOOL_OPTIONS", "-javaagent:" + MOUNT_PATH),
+        Map.entry("OTEL_METRIC_EXPORT_INTERVAL", "100"), // 100 ms
+        Map.entry("OTEL_AWS_APPLICATION_SIGNALS_ENABLED", "true"),
+        Map.entry("OTEL_AWS_APPLICATION_SIGNALS_RUNTIME_ENABLED", isRuntimeEnabled()),
+        Map.entry("OTEL_METRICS_EXPORTER", "none"),
+        Map.entry("OTEL_BSP_SCHEDULE_DELAY", "0"), // Don't wait to export spans to the collector
+        Map.entry("OTEL_AWS_APPLICATION_SIGNALS_EXPORTER_ENDPOINT", COLLECTOR_HTTP_ENDPOINT),
+        Map.entry("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT", COLLECTOR_HTTP_ENDPOINT),
+        Map.entry("OTEL_RESOURCE_ATTRIBUTES", getApplicationOtelResourceAttributes()),
+        Map.entry("OTEL_EXPORTER_OTLP_PROTOCOL", "grpc"),
+        Map.entry("OTEL_TRACES_SAMPLER", "parentbased_always_on"));
   }
 
   protected Map<String, String> getApplicationExtraEnvironmentVariables() {

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/AwsApplicationSignalsCustomizerProvider.java

@@ -102,6 +102,16 @@ public class AwsApplicationSignalsCustomizerProvider
   private static final String OTEL_BSP_MAX_EXPORT_BATCH_SIZE_CONFIG =
       "otel.bsp.max.export.batch.size";
 
+  private static final String OTEL_METRICS_EXPORTER = "otel.metrics.exporter";
+  private static final String OTEL_LOGS_EXPORTER = "otel.logs.exporter";
+  private static final String OTEL_AWS_APPLICATION_SIGNALS_EXPORTER_ENDPOINT =
+      "otel.aws.application.signals.exporter.endpoint";
+  private static final String OTEL_EXPORTER_OTLP_PROTOCOL = "otel.exporter.otlp.protocol";
+  private static final String OTEL_EXPORTER_OTLP_TRACES_ENDPOINT =
+      "otel.exporter.otlp.traces.endpoint";
+  private static final String OTEL_TRACES_SAMPLER = "otel.traces.sampler";
+  private static final String OTEL_TRACES_SAMPLER_ARG = "otel.traces.sampler.arg";
+
   // UDP packet can be upto 64KB. To limit the packet size, we limit the exported batch size.
   // This is a bit of a magic number, as there is no simple way to tell how many spans can make a
   // 64KB batch since spans can vary in size.
@@ -140,6 +150,32 @@ private Map<String, String> customizeProperties(ConfigProperties configProps) {
       // Enable AWS Resource Providers
       propsOverride.put(OTEL_RESOURCE_PROVIDERS_AWS_ENABLED, "true");
 
+      if (!isLambdaEnvironment()) {
+        // Check if properties exist in `configProps`, and only set if missing
+        if (configProps.getString(OTEL_METRICS_EXPORTER) == null) {
+          propsOverride.put(OTEL_METRICS_EXPORTER, "none");
+        }
+        if (configProps.getString(OTEL_LOGS_EXPORTER) == null) {
+          propsOverride.put(OTEL_LOGS_EXPORTER, "none");
+        }
+        if (configProps.getString(OTEL_AWS_APPLICATION_SIGNALS_EXPORTER_ENDPOINT) == null) {
+          propsOverride.put(
+              OTEL_AWS_APPLICATION_SIGNALS_EXPORTER_ENDPOINT, "http://localhost:4316/v1/metrics");
+        }
+        if (configProps.getString(OTEL_EXPORTER_OTLP_PROTOCOL) == null) {
+          propsOverride.put(OTEL_EXPORTER_OTLP_PROTOCOL, "http/protobuf");
+        }
+        if (configProps.getString(OTEL_EXPORTER_OTLP_TRACES_ENDPOINT) == null) {
+          propsOverride.put(OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, "http://localhost:4316/v1/traces");
+        }
+        if (configProps.getString(OTEL_TRACES_SAMPLER) == null) {
+          propsOverride.put(OTEL_TRACES_SAMPLER, "xray");
+        }
+        if (configProps.getString(OTEL_TRACES_SAMPLER_ARG) == null) {
+          propsOverride.put(OTEL_TRACES_SAMPLER_ARG, "endpoint=http://localhost:2000");
+        }
+      }
+
       if (isApplicationSignalsRuntimeEnabled(configProps)) {
         List<String> list = configProps.getList(OTEL_JMX_TARGET_SYSTEM_CONFIG);
         if (list.contains("jvm")) {