Add public API to access environment resource (#5554)

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/ResourceConfiguration.java

@@ -11,25 +11,69 @@
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigurationException;
 import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
 import io.opentelemetry.sdk.autoconfigure.spi.internal.ConditionalResourceProvider;
+import io.opentelemetry.sdk.autoconfigure.spi.internal.DefaultConfigProperties;
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.sdk.resources.ResourceBuilder;
 import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
 import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;
 import java.nio.charset.StandardCharsets;
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.BiFunction;
 
 /** Auto-configuration for the OpenTelemetry {@link Resource}. */
-final class ResourceConfiguration {
+public final class ResourceConfiguration {
 
   // Visible for testing
   static final String ATTRIBUTE_PROPERTY = "otel.resource.attributes";
   static final String SERVICE_NAME_PROPERTY = "otel.service.name";
   static final String DISABLED_ATTRIBUTE_KEYS = "otel.experimental.resource.disabled.keys";
 
+  /**
+   * Create a {@link Resource} from the environment. The resource contains attributes parsed from
+   * environment variables and system property keys {@code otel.resource.attributes} and {@code
+   * otel.service.name}.
+   *
+   * @return the resource.
+   */
+  public static Resource createEnvironmentResource() {
+    return createEnvironmentResource(DefaultConfigProperties.create(Collections.emptyMap()));
+  }
+
+  /**
+   * Create a {@link Resource} from the environment. The resource contains attributes parsed from
+   * environment variables and system property keys {@code otel.resource.attributes} and {@code
+   * otel.service.name}.
+   *
+   * @param config the {@link ConfigProperties} used to obtain resource properties
+   * @return the resource.
+   */
+  public static Resource createEnvironmentResource(ConfigProperties config) {
+    AttributesBuilder resourceAttributes = Attributes.builder();
+    try {
+      for (Map.Entry<String, String> entry : config.getMap(ATTRIBUTE_PROPERTY).entrySet()) {
+        resourceAttributes.put(
+            entry.getKey(),
+            // Attributes specified via otel.resource.attributes follow the W3C Baggage spec and
+            // characters outside the baggage-octet range are percent encoded
+            // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#specifying-resource-information-via-an-environment-variable
+            URLDecoder.decode(entry.getValue(), StandardCharsets.UTF_8.displayName()));
+      }
+    } catch (UnsupportedEncodingException e) {
+      // Should not happen since always using standard charset
+      throw new ConfigurationException("Unable to decode resource attributes.", e);
+    }
+    String serviceName = config.getString(SERVICE_NAME_PROPERTY);
+    if (serviceName != null) {
+      resourceAttributes.put(ResourceAttributes.SERVICE_NAME, serviceName);
+    }
+
+    return Resource.create(resourceAttributes.build(), ResourceAttributes.SCHEMA_URL);
+  }
+
   static Resource configureResource(
       ConfigProperties config,
       ClassLoader serviceClassLoader,
@@ -56,41 +100,11 @@ static Resource configureResource(
       result = result.merge(resourceProvider.createResource(config));
     }
 
-    result = result.merge(createEnvironmentResource(config));
-
     result = filterAttributes(result, config);
 
     return resourceCustomizer.apply(result, config);
   }
 
-  private static Resource createEnvironmentResource(ConfigProperties config) {
-    return Resource.create(getAttributes(config), ResourceAttributes.SCHEMA_URL);
-  }
-
-  // visible for testing
-  static Attributes getAttributes(ConfigProperties configProperties) {
-    AttributesBuilder resourceAttributes = Attributes.builder();
-    try {
-      for (Map.Entry<String, String> entry :
-          configProperties.getMap(ATTRIBUTE_PROPERTY).entrySet()) {
-        resourceAttributes.put(
-            entry.getKey(),
-            // Attributes specified via otel.resource.attributes follow the W3C Baggage spec and
-            // characters outside the baggage-octet range are percent encoded
-            // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/sdk.md#specifying-resource-information-via-an-environment-variable
-            URLDecoder.decode(entry.getValue(), StandardCharsets.UTF_8.displayName()));
-      }
-    } catch (UnsupportedEncodingException e) {
-      // Should not happen since always using standard charset
-      throw new ConfigurationException("Unable to decode resource attributes.", e);
-    }
-    String serviceName = configProperties.getString(SERVICE_NAME_PROPERTY);
-    if (serviceName != null) {
-      resourceAttributes.put(ResourceAttributes.SERVICE_NAME, serviceName);
-    }
-    return resourceAttributes.build();
-  }
-
   // visible for testing
   static Resource filterAttributes(Resource resource, ConfigProperties configProperties) {
     Set<String> disabledKeys = new HashSet<>(configProperties.getList(DISABLED_ATTRIBUTE_KEYS));

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/internal/EnvironmentResourceProvider.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.autoconfigure.internal;
+
+import io.opentelemetry.sdk.autoconfigure.ResourceConfiguration;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
+import io.opentelemetry.sdk.resources.Resource;
+
+/**
+ * {@link ResourceProvider} for automatically configuring {@link
+ * ResourceConfiguration#createEnvironmentResource(ConfigProperties)}.
+ */
+public final class EnvironmentResourceProvider implements ResourceProvider {
+  @Override
+  public Resource createResource(ConfigProperties config) {
+    return ResourceConfiguration.createEnvironmentResource(config);
+  }
+
+  @Override
+  public int order() {
+    // Environment resource takes precedent over all other ResourceProviders
+    return Integer.MAX_VALUE;
+  }
+}

sdk-extensions/autoconfigure/src/main/resources/META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider

@@ -0,0 +1 @@
+io.opentelemetry.sdk.autoconfigure.internal.EnvironmentResourceProvider

sdk-extensions/autoconfigure/src/test/java/io/opentelemetry/sdk/autoconfigure/ResourceConfigurationFuzzTest.java

@@ -30,11 +30,12 @@ public static class TestCases {
     @Fuzz
     public void getAttributesWithRandomValues(String value1, String value2) {
       Attributes attributes =
-          ResourceConfiguration.getAttributes(
-              DefaultConfigProperties.createForTest(
-                  singletonMap(
-                      ResourceConfiguration.ATTRIBUTE_PROPERTY,
-                      "key1=" + escaper.escape(value1) + ",key2=" + escaper.escape(value2))));
+          ResourceConfiguration.createEnvironmentResource(
+                  DefaultConfigProperties.createForTest(
+                      singletonMap(
+                          ResourceConfiguration.ATTRIBUTE_PROPERTY,
+                          "key1=" + escaper.escape(value1) + ",key2=" + escaper.escape(value2))))
+              .getAttributes();
 
       assertThat(attributes).hasSize(2).containsEntry("key1", value1).containsEntry("key2", value2);
     }

sdk-extensions/autoconfigure/src/test/java/io/opentelemetry/sdk/autoconfigure/ResourceConfigurationTest.java

@@ -7,7 +7,6 @@
 
 import static io.opentelemetry.sdk.autoconfigure.ResourceConfiguration.DISABLED_ATTRIBUTE_KEYS;
 import static io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions.assertThat;
-import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonMap;
 
 import com.google.common.collect.ImmutableMap;
@@ -47,21 +46,21 @@ void customConfigResource() {
   }
 
   @Test
-  void resourceFromConfig_empty() {
-    Attributes attributes =
-        ResourceConfiguration.getAttributes(DefaultConfigProperties.createForTest(emptyMap()));
+  void createEnvironmentResource_Empty() {
+    Attributes attributes = ResourceConfiguration.createEnvironmentResource().getAttributes();
 
     assertThat(attributes).isEmpty();
   }
 
   @Test
-  void resourceFromConfig() {
+  void createEnvironmentResource_WithResourceAttributes() {
     Attributes attributes =
-        ResourceConfiguration.getAttributes(
-            DefaultConfigProperties.createForTest(
-                singletonMap(
-                    ResourceConfiguration.ATTRIBUTE_PROPERTY,
-                    "service.name=myService,appName=MyApp")));
+        ResourceConfiguration.createEnvironmentResource(
+                DefaultConfigProperties.createForTest(
+                    singletonMap(
+                        ResourceConfiguration.ATTRIBUTE_PROPERTY,
+                        "service.name=myService,appName=MyApp")))
+            .getAttributes();
 
     assertThat(attributes)
         .hasSize(2)
@@ -70,25 +69,27 @@ void resourceFromConfig() {
   }
 
   @Test
-  void serviceName() {
+  void createEnvironmentResource_WithServiceName() {
     Attributes attributes =
-        ResourceConfiguration.getAttributes(
-            DefaultConfigProperties.createForTest(
-                singletonMap(ResourceConfiguration.SERVICE_NAME_PROPERTY, "myService")));
+        ResourceConfiguration.createEnvironmentResource(
+                DefaultConfigProperties.createForTest(
+                    singletonMap(ResourceConfiguration.SERVICE_NAME_PROPERTY, "myService")))
+            .getAttributes();
 
     assertThat(attributes).hasSize(1).containsEntry(ResourceAttributes.SERVICE_NAME, "myService");
   }
 
   @Test
-  void resourceFromConfig_overrideServiceName() {
+  void createEnvironmentResource_ServiceNamePriority() {
     Attributes attributes =
-        ResourceConfiguration.getAttributes(
-            DefaultConfigProperties.createForTest(
-                ImmutableMap.of(
-                    ResourceConfiguration.ATTRIBUTE_PROPERTY,
-                    "service.name=myService,appName=MyApp",
-                    ResourceConfiguration.SERVICE_NAME_PROPERTY,
-                    "ReallyMyService")));
+        ResourceConfiguration.createEnvironmentResource(
+                DefaultConfigProperties.createForTest(
+                    ImmutableMap.of(
+                        ResourceConfiguration.ATTRIBUTE_PROPERTY,
+                        "service.name=myService,appName=MyApp",
+                        ResourceConfiguration.SERVICE_NAME_PROPERTY,
+                        "ReallyMyService")))
+            .getAttributes();
 
     assertThat(attributes)
         .hasSize(2)
@@ -97,11 +98,12 @@ void resourceFromConfig_overrideServiceName() {
   }
 
   @Test
-  void resourceFromConfig_emptyEnvVar() {
+  void createEnvironmentResource_EmptyResourceAttributes() {
     Attributes attributes =
-        ResourceConfiguration.getAttributes(
-            DefaultConfigProperties.createForTest(
-                singletonMap(ResourceConfiguration.ATTRIBUTE_PROPERTY, "")));
+        ResourceConfiguration.createEnvironmentResource(
+                DefaultConfigProperties.createForTest(
+                    singletonMap(ResourceConfiguration.ATTRIBUTE_PROPERTY, "")))
+            .getAttributes();
 
     assertThat(attributes).isEmpty();
   }