diff --git a/pom.xml b/pom.xml
index 1521fd72..6dedbf4b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -83,6 +83,7 @@
${jenkins.baseline}.3
3.0.0
false
+ false
diff --git a/src/test/java/test/ssh_agent/OutboundAgent.java b/src/test/java/test/ssh_agent/OutboundAgent.java
new file mode 100644
index 00000000..5dad98b9
--- /dev/null
+++ b/src/test/java/test/ssh_agent/OutboundAgent.java
@@ -0,0 +1,141 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2025 CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package test.ssh_agent;
+
+import com.cloudbees.jenkins.plugins.sshcredentials.impl.BasicSSHUserPrivateKey;
+import com.cloudbees.plugins.credentials.CredentialsProvider;
+import com.cloudbees.plugins.credentials.CredentialsScope;
+import com.cloudbees.plugins.credentials.domains.Domain;
+import hudson.Functions;
+import hudson.plugins.sshslaves.SSHLauncher;
+import hudson.slaves.DumbSlave;
+import java.io.ByteArrayOutputStream;
+import java.io.Serializable;
+import java.nio.charset.StandardCharsets;
+import org.apache.sshd.common.config.keys.KeyUtils;
+import org.apache.sshd.common.config.keys.writer.openssh.OpenSSHKeyPairResourceWriter;
+import org.apache.sshd.common.keyprovider.KeyPairProvider;
+import org.jvnet.hudson.test.JenkinsRule;
+import org.testcontainers.DockerClientFactory;
+import org.testcontainers.containers.GenericContainer;
+
+/**
+ * Test utility to create an outbound agent.
+ * Will use Docker when it is available (Testcontainers must be in your plugin classpath),
+ * which is preferable as it ensures that the process and filesystem namespace for the agent
+ * is distinct from that of the controller.
+ * Otherwise it falls back to running an agent process locally.
+ */
+public final class OutboundAgent implements AutoCloseable {
+
+ private String image = "jenkins/ssh-agent";
+
+ private SSHAgentContainer container;
+
+ public OutboundAgent() {}
+
+ /**
+ * Overrides the container image, by default {@code jenkins/ssh-agent} (latest).
+ */
+ public OutboundAgent withImage(String image) {
+ this.image = image;
+ return this;
+ }
+
+ private static final class SSHAgentContainer extends GenericContainer {
+ final String privateKey;
+
+ SSHAgentContainer(String image) {
+ super(image);
+ try {
+ var kp = KeyUtils.generateKeyPair(KeyPairProvider.SSH_RSA, 2048);
+ var kprw = new OpenSSHKeyPairResourceWriter();
+ var baos = new ByteArrayOutputStream();
+ kprw.writePublicKey(kp, null, baos);
+ var pub = baos.toString(StandardCharsets.US_ASCII);
+ baos.reset();
+ kprw.writePrivateKey(kp, null, null, baos);
+ privateKey = baos.toString(StandardCharsets.US_ASCII);
+ withEnv("JENKINS_AGENT_SSH_PUBKEY", pub);
+ withExposedPorts(22);
+ } catch (Exception x) {
+ throw new AssertionError(x);
+ }
+ }
+ }
+
+ /**
+ * Start the container, if Docker is available.
+ * @return Docker connection details, or null if running locally; pass to {@link #createAgent}
+ */
+ public ConnectionDetails start() throws Exception {
+ if (!Functions.isWindows() && DockerClientFactory.instance().isDockerAvailable()) {
+ container = new SSHAgentContainer(image);
+ container.start();
+ return new ConnectionDetails(container.getHost(), container.getMappedPort(22), container.privateKey);
+ } else {
+ return null;
+ }
+ }
+
+ /**
+ * Treat as opaque between {@link #start} and {@link #createAgent}.
+ */
+ public record ConnectionDetails(String host, int port, String privateKey) implements Serializable {}
+
+ /**
+ * Create an agent.
+ * @param rule this should run in the controller’s’ JVM, unlike {@link #start}
+ * @param name agent name
+ * @param connectionDetails connection details, or null to run a local agent
+ * @see JenkinsRule#waitOnline
+ */
+ public static void createAgent(JenkinsRule rule, String name, ConnectionDetails connectionDetails)
+ throws Exception {
+ if (connectionDetails != null) {
+ var creds = new BasicSSHUserPrivateKey(
+ CredentialsScope.GLOBAL,
+ null,
+ "jenkins",
+ new BasicSSHUserPrivateKey.DirectEntryPrivateKeySource(connectionDetails.privateKey),
+ null,
+ null);
+ CredentialsProvider.lookupStores(rule.jenkins).iterator().next().addCredentials(Domain.global(), creds);
+ rule.jenkins.addNode(new DumbSlave(
+ name,
+ "/home/jenkins/agent",
+ new SSHLauncher(connectionDetails.host, connectionDetails.port, creds.getId())));
+ } else {
+ rule.createSlave(name, null, null);
+ }
+ }
+
+ @Override
+ public void close() throws Exception {
+ if (container != null) {
+ container.close();
+ }
+ }
+}
diff --git a/src/test/java/test/ssh_agent/OutboundAgentRJRTest.java b/src/test/java/test/ssh_agent/OutboundAgentRJRTest.java
new file mode 100644
index 00000000..8879e50b
--- /dev/null
+++ b/src/test/java/test/ssh_agent/OutboundAgentRJRTest.java
@@ -0,0 +1,50 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2025 CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package test.ssh_agent;
+
+import hudson.model.Slave;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.RealJenkinsRule;
+
+public final class OutboundAgentRJRTest {
+
+ @Rule
+ public final RealJenkinsRule rr = new RealJenkinsRule();
+
+ @Test
+ public void smokes() throws Throwable {
+ rr.startJenkins();
+ try (var outbountAgent = new OutboundAgent()) {
+ rr.runRemotely(OutboundAgent::createAgent, "remote", outbountAgent.start());
+ rr.run(r -> {
+ var agent = (Slave) r.jenkins.getNode("remote");
+ r.waitOnline(agent);
+ System.err.println(
+ "Running in " + agent.toComputer().getEnvironment().get("PWD"));
+ });
+ }
+ }
+}