Allow configuring resource root of transport versions (elastic#133093)

This commit adds the manifest file name as an argument when loading
transport versions from resource files. This allows multiple manifests
to exist on the test classpath at once, eg in serverless.

Author: rjernst

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/transport/TransportVersionResourcesPlugin.java

@@ -61,8 +61,9 @@ public void apply(Project project) {
                 t.getDefinitionsDirectory().set(getDefinitionsDirectory(getResourcesDirectory(project)));
                 t.getManifestFile().set(project.getLayout().getBuildDirectory().file("generated-resources/manifest.txt"));
             });
+        String resourceRoot = TransportVersionUtils.getResourceRoot(project);
         project.getTasks().named(JavaPlugin.PROCESS_RESOURCES_TASK_NAME, Copy.class).configure(t -> {
-            t.into("transport/definitions", c -> c.from(generateManifestTask));
+            t.into(resourceRoot + "/definitions", c -> c.from(generateManifestTask));
         });
     }
 }

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/transport/TransportVersionUtils.java

@@ -50,7 +50,16 @@ static Directory getResourcesDirectory(Project project) {
         if (projectName == null) {
             projectName = ":server";
         }
+        var resourceRoot = getResourceRoot(project);
         Directory projectDir = project.project(projectName.toString()).getLayout().getProjectDirectory();
-        return projectDir.dir("src/main/resources/transport");
+        return projectDir.dir("src/main/resources/" + resourceRoot);
+    }
+
+    static String getResourceRoot(Project project) {
+        var resourceRoot = project.findProperty("org.elasticsearch.transport.resourceRoot");
+        if (resourceRoot == null) {
+            resourceRoot = "transport";
+        }
+        return resourceRoot.toString();
     }
 }

server/src/main/java/org/elasticsearch/TransportVersion.java

@@ -163,31 +163,32 @@ public static TransportVersion fromBufferedReader(
         }
     }
 
-    public static List<TransportVersion> collectFromInputStreams(
+    public static List<TransportVersion> collectFromResources(
         String component,
-        Function<String, InputStream> nameToStream,
+        String resourceRoot,
+        Function<String, InputStream> resourceLoader,
         String latestFileName
     ) {
         TransportVersion latest = parseFromBufferedReader(
             component,
-            "/transport/latest/" + latestFileName,
-            nameToStream,
+            resourceRoot + "/latest/" + latestFileName,
+            resourceLoader,
             (c, p, br) -> fromBufferedReader(c, p, true, false, br, Integer.MAX_VALUE)
         );
         if (latest != null) {
             List<String> versionRelativePaths = parseFromBufferedReader(
                 component,
-                "/transport/definitions/manifest.txt",
-                nameToStream,
+                resourceRoot + "/definitions/manifest.txt",
+                resourceLoader,
                 (c, p, br) -> br.lines().filter(line -> line.isBlank() == false).toList()
             );
             if (versionRelativePaths != null) {
                 List<TransportVersion> transportVersions = new ArrayList<>();
                 for (String versionRelativePath : versionRelativePaths) {
                     TransportVersion transportVersion = parseFromBufferedReader(
                         component,
-                        "/transport/definitions/" + versionRelativePath,
-                        nameToStream,
+                        resourceRoot + "/definitions/" + versionRelativePath,
+                        resourceLoader,
                         (c, p, br) -> fromBufferedReader(c, p, false, versionRelativePath.startsWith("named/"), br, latest.id())
                     );
                     if (transportVersion != null) {
@@ -426,8 +427,9 @@ private static class VersionsHolder {
         static {
             // collect all the transport versions from server and es modules/plugins (defined in server)
             List<TransportVersion> allVersions = new ArrayList<>(TransportVersions.DEFINED_VERSIONS);
-            List<TransportVersion> streamVersions = collectFromInputStreams(
+            List<TransportVersion> streamVersions = collectFromResources(
                 "<server>",
+                "/transport",
                 TransportVersion.class::getResourceAsStream,
                 Version.CURRENT.major + "." + Version.CURRENT.minor + ".csv"
             );