# How to manage classpath when using shared-lib?

**URL:** <https://community.jenkins.io/t/how-to-manage-classpath-when-using-shared-lib/35603>\
**Category:** Using Jenkins\
**Created:** [September 17, 2025, 1:30pm UTC](https://community.jenkins.io/t/how-to-manage-classpath-when-using-shared-lib/35603 "2025-09-17T13:30:50Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![sngbango](https://avatars.discourse-cdn.com/v4/letter/s/bc8723/32.png) [@sngbango](https://community.jenkins.io/u/sngbango)\
**Post date:** [September 17, 2025, 1:30pm UTC](https://community.jenkins.io/t/how-to-manage-classpath-when-using-shared-lib/35603/1 "2025-09-17T13:30:50Z")

</div>

Jenkins setup:

1. **OS** : RHEL 9
2. **Jenkins** : 2.516.2
3. **Java** : OpenJDK 21
4. **Installation** : RPM, systemd service
5. **JENKINS\_HOME** : /lun/data1/jenkins
6. **Shared Library** : Git-based, with src/ and vars/

### Configuration:

In my systemd override (systemctl edit jenkins):

```bash
[Service]
Environment="JENKINS_HOME=/lun/data1/jenkins"
Environment="JAVA_OPTS=-Djava.awt.headless=true -cp /lun/data1/jenkins/.jenkins/lib/"
Environment="JENKINS_PORT=8080"
User=jenkins

```

- JARs are in /lun/data1/jenkins/.jenkins/lib/ (permissions: chown jenkins:jenkins, chmod 750).

- Shared library tries to use classes from these JARs (e.g., Class.forName(‘com.external.MyClass’)).

### Issue:

Pipelines fail with:

```bash
java.lang.ClassNotFoundException: com.external.MyClass

 No suitable driver found for jdbc:postgresql

```

### Tried:

1. Added JARs to /lun/data1/jenkins/.jenkins/lib/ and updated JAVA\_OPTS.

2. Tested Grape (@Grapes(@Grab(‘org.apache.commons:commons-lang3:3.12.0’))), but slow and needs sandbox approvals.

3. Considered addToClasspath (Pipeline Classpath Step plugin), but it’s deprecated.

4. Checked logs (/var/log/jenkins/jenkins.log): No errors except class loading failures.

### Questions:

- Why aren’t JARs in /lun/data1/jenkins/.jenkins/lib/ loaded?

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<div class="post-metadata">

**Author:** ![poddingue](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/poddingue/32/985_2.png) [@poddingue](https://community.jenkins.io/u/poddingue)\
**Post date:** [September 17, 2025, 1:35pm UTC](https://community.jenkins.io/t/how-to-manage-classpath-when-using-shared-lib/35603/2 "2025-09-17T13:35:50Z")

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Hello and welcome to this community, @sngbango. 👋

Jenkins doesn’t automatically load JARs from arbitrary directories (like `/lun/data1/jenkins/.jenkins/lib/`) into the Groovy sandbox or the pipeline shared library classpath.

Things like `-cp` or setting `CLASSPATH` in `JAVA_OPTS` only affect the initial JVM classpath when Jenkins starts. They don’t influence what’s visible to pipeline or shared library code later on.

A few reasons why this happens:

- Pipeline and shared library code runs inside a restricted Groovy sandbox, which is intentionally isolated from the main Jenkins JVM classpath for security.
- The pipeline shared library mechanism doesn’t inherit the JVM classpath or pick up JARs from custom paths.
- By default, only Jenkins core and installed plugin classes are available.

If you want to use external JARs in a pipeline, here are the supported options:

- **Grape / `@Grab` annotations** in Groovy — though this can be slow and often requires sandbox approvals.
- **Pipeline: Classpath Step** — exists but is deprecated and not recommended anymore.
- **Build a Jenkins plugin** that bundles your JARs and install it.
- **Global shared libraries** — but note they only load Groovy/Java code from `src/` and `vars/`, not standalone JARs.
- **Call your Java code externally** from the pipeline using `sh` or `bat` steps, and provide the JARs there.

So, in short: Jenkins won’t pick up JARs you drop into `/lun/data1/jenkins/.jenkins/lib/` for pipeline libraries. To make them available, you’ll need to use one of the supported mechanisms like a plugin, Grape, or an external process.

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**Author:** ![mawinter69](https://dub1.discourse-cdn.com/flex013/user_avatar/community.jenkins.io/mawinter69/32/1625_2.png) [@mawinter69](https://community.jenkins.io/u/mawinter69)\
**Post date:** [September 17, 2025, 2:24pm UTC](https://community.jenkins.io/t/how-to-manage-classpath-when-using-shared-lib/35603/3 "2025-09-17T14:24:24Z")

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If it is about postgres there are plugins available that provide the jars

> **[Search Results](https://plugins.jenkins.io/ui/search/?query=postgres)**
>
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