Uploading a File via SCP with Maven fails

I try to upload an ear created by maven to an application server using scp.

When I tried to run

mvn wagon:upload-single

But I get the following error:

[ERROR] Failed to execute goal org.codehaus.mojo:wagon-maven-plugin:1.0-beta-3:upload-single (default-cli) on project de.volkswagen.dps.ear: Unable to create a Wagon instance for null: url can not be null -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:wagon-maven-plugin:1.0-beta-3:upload-single (default-cli) on project de.volkswagen.dps.ear: Unable to create a Wagon instance for null
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:585)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:324)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:247)
    at org.apache.m开发者_如何学JAVAaven.DefaultMaven.execute(DefaultMaven.java:104)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:427)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:157)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:121)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.MojoExecutionException: Unable to create a Wagon instance for null
    at org.codehaus.mojo.wagon.AbstractWagonMojo.createWagon(AbstractWagonMojo.java:83)
    at org.codehaus.mojo.wagon.AbstractSingleWagonMojo.execute(AbstractSingleWagonMojo.java:62)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:105)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:577)
    ... 14 more
Caused by: java.lang.NullPointerException: url can not be null
    at org.apache.maven.wagon.repository.Repository.(Repository.java:88)
    at org.codehaus.mojo.wagon.shared.WagonUtils.createWagon(WagonUtils.java:51)
    at org.codehaus.mojo.wagon.AbstractWagonMojo.createWagon(AbstractWagonMojo.java:79)
    ... 17 more

I tried to add this to the pom, but it doesn't seem to have any effect:

I added the following to the pom.xml:

...
    <extensions>
        <extension>
            <groupId>org.apache.maven.wagon</groupId>
            <artifactId>wagon-ssh</artifactId>
            <version>1.0-beta-6</version>
        </extension>
    </extensions>

    <plugins>

        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>wagon-maven-plugin</artifactId>
            <version>1.0-beta-3</version>
            <executions>
                <execution>
                    <id>upload-ear</id>
                    <phase>deploy</phase>
                    <goals>
                        <goal>upload</goal>
                    </goals>
                    <configuration>
                        <fromFile>${project.build.directory}/${project.build.finalName}.ear</fromFile> 
                        <url>scp://servername/</url>
                        <toDir>.</toDir>
                    </configuration>
                </execution>
            </executions>
        </plugin>
....

Can anybody explain how I can make this work?

Your current configuration follows the example given in the Usage page and is correct. However, in this example the configuration element is declared inside an execution and thus only applies to this particular execution.

So when you call mvn wagon:upload-single on the command line, the configuration isn't "used" and there is indeed no url parameter configured.

If you want to call the plugin from the command line, either pass the parameters on the command line using -Durl=foo and so on or add a "global" configuration element:

<build>
  <extensions>
    <extension>
      <groupId>org.apache.maven.wagon</groupId>
      <artifactId>wagon-ssh</artifactId>
      <version>1.0-beta-6</version>
    </extension>
  </extensions>  

  <plugins>   
    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>wagon-maven-plugin</artifactId>
      <version>1.0-beta-3</version>
      <configuration>
        <fromFile>${project.build.directory}/${project.build.finalName}.ear</fromFile> 
        <url>scp://servername/</url>
        <toDir>.</toDir>
      </configuration>
      ...
    </plugin>
    ...
  </plugins>
  ...
</build>

You can run the following command to run the plugin using the configuration on your pom.xml:

mvn org.codehaus.mojo:wagon-maven-plugin:upload@upload-ear