CAMEL-23216: Fix flaky mina sftp tests

test-infra/camel-test-infra-ftp/src/main/java/org/apache/camel/test/infra/ftp/services/embedded/SftpEmbeddedInfraService.java

@@ -20,13 +20,15 @@
 import java.io.File;
 import java.io.IOException;
 import java.net.InetSocketAddress;
+import java.net.Socket;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.security.KeyPair;
 import java.security.PublicKey;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 import java.util.function.BiConsumer;
 
 import org.apache.camel.spi.annotations.InfraService;
@@ -136,6 +138,23 @@ public void setUpServer() throws Exception {
         sshd.start();
 
         port = ((InetSocketAddress) sshd.getBoundAddresses().iterator().next()).getPort();
+
+        waitForServerReady();
+    }
+
+    private void waitForServerReady() throws IOException {
+        long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(30);
+        IOException lastException = null;
+        while (System.nanoTime() < deadline) {
+            try (Socket socket = new Socket()) {
+                socket.connect(new InetSocketAddress("localhost", port), 1000);
+                return;
+            } catch (IOException e) {
+                lastException = e;
+                Thread.onSpinWait();
+            }
+        }
+        throw new IOException("SFTP server not ready after 30 seconds on port " + port, lastException);
     }
 
     protected PublickeyAuthenticator getPublickeyAuthenticator() {