Route cluster metadata to writable primary

test/cloud/lunarsky/store/ClusterMetadataTest.java

@@ -0,0 +1,63 @@
+package cloud.lunarsky.store;
+
+import com.sun.net.httpserver.HttpServer;
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.sql.DriverManager;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+public final class ClusterMetadataTest {
+    public static void main(String[] args) throws Exception {
+        Map<String, String> env = System.getenv();
+        String token = "metadata-test-cluster-token-0123456789";
+        String repairToken = "metadata-test-repair-token-0123456789";
+        Path root = Files.createTempDirectory("objectstore-metadata-test-");
+        try (ClusterNode first = new ClusterNode(root.resolve("first"), token, repairToken, UUID.randomUUID());
+             ClusterNode second = new ClusterNode(root.resolve("second"), token, repairToken, UUID.randomUUID())) {
+            HttpServer firstServer = server(first);
+            HttpServer secondServer = server(second);
+            try {
+                List<URI> nodes = List.of(url(firstServer), url(secondServer));
+                try (ClusterStore store = new ClusterStore(env.get("POSTGRES_JDBC_URL"),
+                        env.get("POSTGRES_USER"), env.get("POSTGRES_PASSWORD"), "objects",
+                        nodes, token, repairToken, 1024 * 1024, 16 * 1024 * 1024, false)) {
+                    require(store.ready(), "Writable primary was not selected from the multi-host URL");
+                    try (var admin = DriverManager.getConnection(env.get("POSTGRES_ADMIN_JDBC_URL"),
+                            env.get("POSTGRES_USER"), env.get("POSTGRES_PASSWORD"));
+                         var statement = admin.createStatement()) {
+                        statement.execute("ALTER DATABASE objectstore_test SET default_transaction_read_only=on");
+                        try {
+                            require(!store.ready(), "Read-only metadata was reported ready");
+                        } finally {
+                            statement.execute("ALTER DATABASE objectstore_test RESET default_transaction_read_only");
+                        }
+                    }
+                    require(store.ready(), "Writable metadata did not recover after read-only mode ended");
+                }
+            } finally {
+                firstServer.stop(0);
+                secondServer.stop(0);
+            }
+        }
+        System.out.println("Metadata routing tests passed: second JDBC host and writable readiness");
+    }
+
+    private static HttpServer server(ClusterNode node) throws Exception {
+        HttpServer server = HttpServer.create(new InetSocketAddress("127.0.0.1", 0), 0);
+        server.createContext("/", node::handle);
+        server.start();
+        return server;
+    }
+
+    private static URI url(HttpServer server) {
+        return URI.create("http://127.0.0.1:" + server.getAddress().getPort());
+    }
+
+    private static void require(boolean condition, String message) {
+        if (!condition) throw new AssertionError(message);
+    }
+}