Allow setting up ssh-agent before SCM. This way git can as well use the ssh-agent settings.

Author: Patrick Boos

src/main/java/com/cloudbees/jenkins/plugins/sshagent/SSHAgentBuildWrapper.java

@@ -55,6 +55,7 @@ public class SSHAgentBuildWrapper extends BuildWrapper {
      * The {@link com.cloudbees.jenkins.plugins.sshcredentials.SSHUser#getId()} of the credentials to use.
      */
     private final String user;
+    private final boolean runBeforeSCM;
 
     /**
      * Constructs a new instance.
@@ -63,8 +64,9 @@ public class SSHAgentBuildWrapper extends BuildWrapper {
      */
     @DataBoundConstructor
     @SuppressWarnings("unused") // used via stapler
-    public SSHAgentBuildWrapper(String user) {
+    public SSHAgentBuildWrapper(String user, boolean runBeforeSCM) {
         this.user = user;
+        this.runBeforeSCM = runBeforeSCM;
     }
 
     /**
@@ -77,12 +79,46 @@ public String getUser() {
         return user;
     }
 
+    /**
+     * Gets the runBeforeSCM setting. If set to true, this will create the environment before SCM
+     * (at {@link com.cloudbees.jenkins.plugins.sshagent.SSHAgentBuildWrapper#preCheckout(hudson.model.AbstractBuild, hudson.Launcher, hudson.model.BuildListener)}).
+     * Otherwise it will return the environment in
+     * {@link com.cloudbees.jenkins.plugins.sshagent.SSHAgentBuildWrapper#setUp(hudson.model.AbstractBuild, hudson.Launcher, hudson.model.BuildListener)}.
+     *
+     * @return true if SSHAgentEnvironment gets created in preCheckout(...), otherwise created in setUp(...).
+     */
+    @SuppressWarnings("unused") // used via stapler
+    public boolean getRunBeforeSCM() {
+        return runBeforeSCM;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void preCheckout(AbstractBuild build, Launcher launcher, BuildListener listener) throws IOException, InterruptedException {
+        if (runBeforeSCM) {
+            build.getEnvironments().add(createSSHAgentEnvironment(build, launcher, listener));
+        }
+    }
+
     /**
      * {@inheritDoc}
      */
     @Override
     public Environment setUp(AbstractBuild build, final Launcher launcher, BuildListener listener)
             throws IOException, InterruptedException {
+        if (runBeforeSCM) {
+            // Jenkins needs this:
+            // null would stop the build, and super implementation throws UnsupportedOperationException
+            return new Environment() {
+            };
+        }
+
+        return createSSHAgentEnvironment(build, launcher, listener);
+    }
+
+    private Environment createSSHAgentEnvironment(AbstractBuild build, Launcher launcher, BuildListener listener) {
         SSHUserPrivateKey userPrivateKey = null;
         for (SSHUserPrivateKey u : CredentialsProvider
                 .lookupCredentials(SSHUserPrivateKey.class, build.getProject(), ACL.SYSTEM)) {

src/main/resources/com/cloudbees/jenkins/plugins/sshagent/SSHAgentBuildWrapper/config.jelly

@@ -27,4 +27,7 @@
   <f:entry title="${%Credentials}" field="user">
     <f:select/>
   </f:entry>
+  <f:entry title="${%Run before SCM}" field="runBeforeSCM">
+    <f:checkbox />
+  </f:entry>
 </j:jelly>