Create a Jenkins Pipeline

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Overview

GitLab’s Jenkins integration allows you to trigger a Jenkins build when you push code to a repository, or when a merge request is created. Additionally, it shows the pipeline status on merge requests widgets and on the project’s home page.

This tutorial shows you how to create a project with a Jenkinsfile, configure a project on the Jenkins server, configure the GitLab Jenkins integration plugin, enable the integration on your GitLab project, and perform a commit to show how pipelines are integrated between GitLab and Jenkins.

Step-by-Step Instructions

Task 1: Create a project for Jenkins CI pipeline integration

If you are just getting started with Jenkins, please follow the instructions in Option A to use our tutorial app that is a Ruby application with a pre-created Jenkinsfile.

If you're using your own existing project, please follow the instructions in Option B to add a Jenkinsfile to your application.

Option A: Create a new project using the tutorial app template

Visit https://gitlab-core.us.gitlabdemo.cloud and sign in with your Demo Cloud SSO credentials.
Create a new project and select the Create from template tab.
In the list of available projects, select the Instance tab.
Find Tutorial App - Jenkins Pipeline and click the Use template button.
In the new project form, use the following values:
- Project name: Tutorial App - Jenkins Pipeline
- Project URL: Groups > demosys-users/{MY-USERNAME}
- Project slug: tutorial-app-jenkins-pipeline
- Project description: (leave blank)
- Visibility Level: Private
After filling in the form, click the Create project button.

Option B: Add a `Jenkinsfile` to your existing project

If you're using your own project, you will need to create a new file named Jenkinsfile (without a file extension) in the top-level directory of your project where your README file is.

/app/
  ...
.gitignore
Jenkinsfile
README.md

As a starting point, you can use the examples provided in the Jenkins docs based on the language of your application.

Jenkinsfile Examples

You can reference the Jenkins docs for more detailed pipeline configurations, however that is outside the scope of this tutorial.

You can reference the open source Jenkins GitLab plugin documentation for more information on additional options.

Task 2. Connect to the Jenkins Server

Visit https://gitlabdemo.com and sign in with your Demo Cloud SSO credentials.
On the Dashboard, you will see all of the Demo Cloud resources that you have access to.
Locate the Jenkins Integration card (bordered section).
Click the blue Jenkins Dashboard button to open a new tab and access the Jenkins server.
You may or may not be prompted to sign in with your Demo Cloud SSO credentials depending on your browser session state. We have designed the integration to automatically sign in and take you to the dashboard.

In the Demo Cloud, we have configured the Jenkins server to use GitLab OAUTH for authentication. Keep in mind that this uses your Demo Cloud credentials and not your GitLab.com credentials.
You will be directed to the dashboard with pipeline jobs and folders.

Task 3. Create a Jenkins folder for your projects

Keep in mind that this is a shared environment and it is best practice create a folder with your username to keep your pipelines in and keep things tidy on the dashboard.

In the left sidebar, click New Item.
In the Enter an item name field, type in your GitLab Demo Cloud username (ex. jeffersonmartin).

If you don't remember your username, switch back to the tab with the GitLab project. If you look in the browser URL, you can determine your username based on the path to your project.
Click the Folder type from the list of options.
Click the OK button in the bottom left corner.
When your folder is created, you will be redirected to a folder details page. You do not need to make any changes here.

Task 4. Create a Jenkins project

In the top left of the page, click the Jenkins logo to navigate to the dashboard.

It is understandable that the Jenkins UI can be a challenge to navigate. If you have any challenges, simply click on the Jenkins logo in the top left to go back to the dashboard and navigate from there.
Locate the folder for your username and click on the folder name hyperlink to navigate to the folder's dashboard.
In the left sidebar, click New item.

:::tip Create new items in your folder Keep in mind that since you're inside a folder, this item will be created in this folder and not at the top-level. It's easy to make this mistake so please be conscientious of this to avoid cluttering up the dashboard with uncategorized projects. :::
In the Enter an item name field, type in the hyphenated URL name (slug) of your GitLab project.
```
 Example
 tutorial-app-jenkins-pipeline
```
Click the Freestyle project type from the list of options.
Click the OK button in the bottom left corner.
You will be redirected to the project configuration page.

Task 5. Configure Jenkins project to integrate with GitLab

If you are not on the project configuration page from the previous task, you can navigate here from the dashboard by clicking on your folder, then your project and clicking Configure link in the left sidebar.

In the General section, enable the checkbox for GitHub project.

One of the cosmetic limitations of the integration is that the GitLab integration use the integration built for GitHub so there is some nomenclature overlap that use the same underlying Git integration.

Below the GitHub project checkbox, locate the Project url field copy/paste or type the URL of your GitLab project.

 Example
 https://gitlab-core.us.gitlabdemo.cloud/demosys-users/jeffersonmartin/tutorial-app-jenkins-pipeline

In the GitLab Connection field, select the GitLab Core US option from the dropdown menu if it's not already selected. This connection was configured by the system administrator earlier.
Scroll down to the Source Code Management section.
Select the Git radio checkbox.
In the expanded section, locate the Repository URL field and copy/paste the GitLab project URL (same URL as step 2).
```
 Example
 https://gitlab-core.us.gitlabdemo.cloud/demosys-users/jeffersonmartin/tutorial-app-jenkins-pipeline
```
You may get an error message about connection error. This is expected behavior since there are no credentials selected. Simply proceed to the next step to select credentials from the dropdown menu.
Locate the Credentials dropdown menu and select the integ_jenkins option. Do not add new credentials in the demo environment.

After you select the integ_jenkins option, the Jenkins server attempts to connect to the API of the GitLab instance to locate your repository URL. If successful, the error message will disappear automatically.
Click the Advanced button.
In the Name field, type in origin.
In the Refspec field, type in the following. This is directly from the documentation and is not customized for the demo environment.
```
+refs/heads/*:refs/remotes/origin/* +refs/merge-requests/*/head:refs/remotes/origin/merge-requests/*
```
In the Branch Specifier field, remove the */master field so that it is blank. This allows jobs to run for all branches (useful when testing a MR).
Scroll down to the Build Triggers section. Enable the checkbox for Build when a change is pushed to GitLab. Leave all options at their default value.
Scroll down to the Build section. Click the Add build step dropdown menu and select the Set build status to "pending" on GitHub commit option.
Scroll down to the Post-build Actions section. Click the Add post-build action dropdown menu and select the Publish build status to GitLab option.
Click the Save button.

Task 6. Generate an API Token for GitLab Integration

In the demo environment, each user generates their own API Token. In a production environment, you may want to create a service account-style user for the integration to simplify administration of API tokens if your security practices allow for that.

In the top left of the page, click the Jenkins logo to navigate to the dashboard.
In the left sidebar, click on People.
In the list of users, locate your account and click on your username.
In the left sidebar, click on Configure.
In the API Token section, click the Add new Token button.
In the form field with the Default name placeholder, type in GitLab integration an click Generate.
Create a new 1Password record or update your GitLab Demo Account record notes with the generated API token.

If you navigate away from this page without copying the token, you will need to generate a new key since this token will not be visible again.

Task 7. Configure GitLab project to integrate with Jenkins

We will configure the integration in GitLab. In some of the plugin documentation, you will see configuration instructions for webhooks which are the previous generation of the integration. Although webhooks can be used, they do not provide the depth of integration that GitLab offers now.

If you still have your GitLab project in a different browser tab or window, you can skip to step 5.

Visit https://gitlabdemo.com.
On the Dashboard, locate the GitLab Omnibus (US) card (bordered section).
Click the blue My Group button to open a new tab and access your group on the GitLab instance.
In the list of projects on Gitlab, click the title of the application you used earlier (Ex. Tutorial App - Jenkins Pipeline).
With the project open, verify that the Jenkinsfile exists in the repository. You do not need to make any changes.

If the file does not exist, go back to Task 1 to create a Jenkinsfile or ensure that you're looking at the same GitLab project you started with earlier.
In the left sidebar, navigate to Settings > CI/CD.
On the CI/CD Settings page, locate Auto DevOps and click the Expand button.
Deselect the checkbox for Default to Auto DevOps pipeline. Click Save changes.
In the left sidebar, navigate to Settings > Integrations.
In the list of integrations, click on Jenkins CI.
Locate the Active checkbox and select to enable it.
In the Jenkins URL field, enter the Jenkins server base URL.
```
https://jenkins.us.gitlabdemo.cloud
```
In the Project name field, enter your folder name and Jenkins project name using {foldername}/{projectname} notation.
```
Example
jeffersonmartin/tutorial-app-jenkins-pipeline
```
In the Username field, enter your GitLab username (the same as your folder name).
In the Enter new password field, copy/paste the new API token that you just generated.
Click the Test settings and save changes button.

If you get an error message, you may need to debug and see if your variables are correct. This is a common area to experience a problem and some light troubleshooting usually fixes the issue.

Task 8. Change a File to Trigger an Commit Event

In the left sidebar, navigate to Repository > Files.
Locate the README.md file and click on the filename.
In the file preview, click the Edit button.
Make a change to the text (change a word, add a line, etc.)
Click the Commit changes button.

Task 9. Review the Jenkins Pipeline in the GitLab UI

In the left sidebar, navigate to CI/CD > Pipelines.
Locate the latest pipeline that passed and click on the pipeline number.
In the pipeline details, right click on the jenkins rounded button under the External group and open in a new tab.
The Jenkins UI will load and you'll see the build job that was executed in Jenkins.
In the left sidebar of the Jenkins UI, click Console Output.
Review the console output to see the details about the job that ran.

Review

You have successfully integrated your GitLab project with Jenkins CI.

There are several approaches to the authentication (shared vs per-user vs per-project), so please consider the best option for your environment when integrating Jenkins.

To learn more about the Jenkins integration, please see the official GitLab documentation.

You can also learn more in the jenkinsci/gitlab-plugin open source integration's README documentation on GitHub.

To learn more about using Jenkins with stages and multiple steps beyond our basic example, please see the Jenkins documentation.