Question: I'm following the tutorial on the [pipeline library plugin](https://github.com/jenkinsci/workflow-cps-global-lib-plugin/blob/master/README.md). I made a repository containing the following files:

```
D:.
│   Test.groovy
│   
├───src
└───vars
        helloWorld.groovy

```

helloWorld.groovy contains:

```
def call(name){
    echo "Hello world, ${name}"
}

```

Test.groovy contains:

```
helloWorld("Joe")

```

I installed all the pipeline plugins, in particular workflow-cps-global-lib-plugin. Then I created a new pipeline job in which I load this repository and set the Script Path to Test.groovy. When I run this job I get the following error:

```
java.lang.NoSuchMethodError: No such DSL method 'helloWorld' found among [archive, bat, build, catchError, checkout, deleteDir, dir, echo, emailext, error, fileExists, git, input, isUnix, jiraComment, jiraIssueSelector, jiraSearch, load, mail, node, parallel, properties, pwd, readFile, readTrusted, retry, sh, sleep, stage, stash, step, svn, timeout, tool, unarchive, unstash, waitUntil, withEnv, wrap, writeFile, ws]

```

Why is the helloWorld step not defined? Here is my list of installed plugins: <http://pastebin.com/xiMMub8J>

Answer: 
The Pipeline Global Library expects a Git push event to update the Jenkins embedded workflow-libs git repo.

A push triggers the `UserDefinedGlobalVariableList.rebuild()` method see: <https://github.com/jenkinsci/workflow-cps-global-lib-plugin/blob/master/src/main/java/org/jenkinsci/plugins/workflow/cps/global/UserDefinedGlobalVariableList.java>

Here is a [groovy script](https://github.com/cloudbees/jenkins-scripts/blob/master/pipeline-global-lib-init.groovy) that pulls a GitHub repo into the Jenkins `workflow-libs` repos and then reloads it without a restart via:

`//Get Pipeline Global Library Jenkins Extension that rebuilds global library on Git Push
List extensions = ExtensionList.lookup(UserDefinedGlobalVariableList.class);
extensions.get(0).rebuild() //may want to add a check here to make sure extensions isn't null`
Using the 2.8 version of Pipeline:Groovy plugin I found that if I update the groovy scripts under /vars/myscript.groovy doesn't work, but if I **restart jenkins** everything works fine.
If I simply reload configuration from file, nothing happens.

So I think the scripts are instantiated as global functions only when jenkins start. (but maybe I'm wrong :) )