Create OtelVersion class at build time. (#5365)

Co-authored-by: jack-berg <34418638+jack-berg@users.noreply.github.com>

buildSrc/src/main/kotlin/io/opentelemetry/gradle/OtelVersionClassPlugin.kt

@@ -0,0 +1,70 @@
+package io.opentelemetry.gradle
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.plugins.JavaPlugin
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.kotlin.dsl.the
+import java.io.File
+
+/**
+ * This gradle plugin will define a new task called generateOtelVersionClass.
+ * This task generates a Java source file that contains the project version
+ * as a string constant. The "compileJava" task is updated to depend on
+ * generateOtelVersionClass, and the project source set is updated to
+ * include the new file.
+ */
+class OtelVersionClassPlugin : Plugin<Project> {
+  override fun apply(project: Project) {
+    project.plugins.apply(JavaPlugin::class.java)
+
+    project.task("generateOtelVersionClass") {
+      doLast {
+        writeFile(project)
+      }
+    }
+    // Add dependency on this task
+    project.tasks.getByName("compileJava") {
+      dependsOn("generateOtelVersionClass")
+    }
+    // Add new source dir to the "main" source set
+    val outDir = buildOutDir(project)
+    val java = project.the<JavaPluginExtension>()
+    java.sourceSets.getByName("main").java {
+      srcDir(outDir)
+    }
+  }
+
+  private fun writeFile(project: Project) {
+    val group = "${project.group}".replace('.', '/')
+    val projectName = project.name.replace('-', '/')
+    val outDir = buildOutDir(project)
+    val filename = "$group/$projectName/internal/OtelVersion.java"
+    val outFile = File(outDir, filename)
+    val packageName = "${project.group}.${project.name.replace('-', '.')}.internal"
+    val classBody = getClassBody("${project.version}", packageName)
+
+    outFile.parentFile.mkdirs()
+    outFile.writeText(classBody)
+  }
+
+  private fun getClassBody(version: String, packageName: String): String {
+    return """
+      package $packageName;
+      
+      import javax.annotation.Generated;
+      
+      /** Autogenerated class do not edit. */
+      @Generated("io.opentelemetry.gradle.OtelVersionClassPlugin")
+      public final class OtelVersion {
+        public static final String VERSION = "$version";
+
+        private OtelVersion() {}
+      }
+    """.trimIndent()
+  }
+
+  private fun buildOutDir(project: Project): File {
+    return File(project.buildDir, "generated/sources/version/java/main")
+  }
+}

buildSrc/src/main/kotlin/io/opentelemetry/gradle/ProtoFieldsWireHandler.kt

@@ -155,7 +155,7 @@ class ProtoFieldsWireHandler : SchemaHandler() {
 
       for (field in type.fieldsAndOneOfFields) {
         builder.addField(
-          FieldSpec.builder(PROTO_FIELD_INFO, field.name.toUpperCase(), PUBLIC, STATIC, FINAL)
+          FieldSpec.builder(PROTO_FIELD_INFO, field.name.uppercase(), PUBLIC, STATIC, FINAL)
             .initializer("\$T.create(\$L, \$L, \"\$L\")",
               PROTO_FIELD_INFO,
               field.tag,

sdk/common/build.gradle.kts

@@ -1,9 +1,11 @@
+import io.opentelemetry.gradle.OtelVersionClassPlugin
+
 plugins {
   id("otel.java-conventions")
   id("otel.publish-conventions")
-
   id("otel.animalsniffer-conventions")
 }
+apply<OtelVersionClassPlugin>()
 
 description = "OpenTelemetry SDK Common"
 otelJava.moduleName.set("io.opentelemetry.sdk.common")

sdk/common/src/main/java/io/opentelemetry/sdk/resources/Resource.java

@@ -16,8 +16,8 @@ import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.common.AttributesBuilder;
 import io.opentelemetry.api.internal.StringUtils;
 import io.opentelemetry.api.internal.Utils;
+import io.opentelemetry.sdk.common.internal.OtelVersion;
 import java.util.Objects;
-import java.util.Properties;
 import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
@@ -54,7 +54,7 @@ public abstract class Resource {
             Attributes.builder()
                 .put(TELEMETRY_SDK_NAME, "opentelemetry")
                 .put(TELEMETRY_SDK_LANGUAGE, "java")
-                .put(TELEMETRY_SDK_VERSION, readVersion())
+                .put(TELEMETRY_SDK_VERSION, OtelVersion.VERSION)
                 .build());
   }
 
@@ -109,18 +109,6 @@ public abstract class Resource {
     return new AutoValue_Resource(schemaUrl, attributes);
   }
 
-  private static String readVersion() {
-    Properties properties = new Properties();
-    try {
-      properties.load(
-          Resource.class.getResourceAsStream("/io/opentelemetry/sdk/common/version.properties"));
-    } catch (Exception e) {
-      // we left the attribute empty
-      return "unknown";
-    }
-    return properties.getProperty("sdk.version", "unknown");
-  }
-
   /**
    * Returns the URL of the OpenTelemetry schema used by this resource. May be null.
    *