The first step is to install the Github and Pipeline plugins, since we will use a Pipeline to clone and build a Github repository.

Task: Install Plugins

1. Within the Dashboard, select Manage Jenkins on the left.
2. On the Configuration page, select Manage Plugins.
3. Manage Plugins page will give you a tabbed interface. Click Available and wait three seconds to view all the Jenkins plugins that can be installed.
4. Using the search box, search for Github plugin and choose the plugin via checkbox.
5. While on this page, search for Pipeline and choose the plugin via checkbox.
6. Click Install without Restart at the bottom.
7. The plugins will now be downloaded and installed. Once complete, click the link Go back to the top page.

Your Jenkins server can now be configured to build a 'hello world' application using pipelines.

Once the plugins have been installed, you can configure how pipelines uses Git and Maven to download and build a hello world application.

Task: Configure Maven Plugin

This step configures the Maven plugin.

1. Once again, select Manage Jenkins.
2. Select Global Tool Configuration.
3. At the bottom, there is a button called Maven installations.... Click it.
4. Choose the name M3.
5. Click the Install automatically checkbox and keep the option Install from Apache with version 3.5.0.
6. Click Apply at the bottom of the page.

Task: Configure Git Plugin

This step configures the Git plugin.

1. In the Manage Jenkins page, find the section Git -> Git installations -> Git.
2. Keep the name Default and check the Install automatically checkbox.
3. From the Add Installer dropdown menue, choose Run Shell Command.
4. Copy the command which git || (apk update && apk upgrade && apk add --no-cache git) into the Command box. This command is valid for the chosen alpine image only and must be adapted for other Linux distributions.
5. In the Tool Home box, enter /usr/bin/git.
6. Click Save at the bottom of the page.

Jenkins Pipelines are now ready to use Git and Maven.

We now will start a pre-configured Jenkins. You can skip this step, if you have accomplished steps 1-3 successfully.

Task: Start pre-configured Jenkins

If you have performed step 1 to 3 already, you can skip this step and go to the next step immediately. If you have skipped setps 1-3, or if they were not successful, follow the following instructions to download a clean pre-configured Jenkins installation:

1. Stop and remove any containers named "jenkins", if required:

docker stop jenkins; docker rm jenkins

1. Download and start a pre-configured Jenkins container.

docker run -d --rm --name jenkins \ -p 8080:8080 -p 50000:50000 \ oveits/jenkins:2.46.2-alpine-nologin-with-maven-git-pipelines

You can load the Jenkins' dashboard via the following URL https://[[HOST_SUBDOMAIN]]-8080-[[KATACODA_HOST]].environments.katacoda.com/ or by clicking the dashboard tab on the right.

Note: the image has been created like follows:

docker run -d -u root --name jenkins \ -p 8080:8080 -p 50000:50000 \ --entrypoint bash \ jenkins:2.46.2-alpine \ -c "tail -F /jenkins.log"

docker exec -d jenkins \ bash -c 'git clone https://github.com/oveits/jenkins_home_alpine \ && export JENKINS_HOME=$(pwd)/jenkins_home_alpine \ && java -jar /usr/share/jenkins/jenkins.war 2>&1 1>/jenkins.log &'

Perform the manual steps 1 to 3.

docker stop jenkins docker commit jenkins newjenkinsimage

Create a new container with the correct entrypoint and CMD: docker run -d --entrypoint "bash" -p 8080:8080 -p 50000:50000 --name jenkins2 newjenkinsimage -c "JENKINS_HOME=/jenkins_home_alpine java -jar /usr/share/jenkins/jenkins.war"

For commiting the

docker stop jenkins2 docker login

Add your user credentials of Docker Hub here...

Then:

docker commit jenkins2 oveits/jenkins:2.46.2-alpine-nologin-with-maven-git-pipelines docker push oveits/jenkins:2.46.2-alpine-nologin-with-maven-git-pipelines

Here you need to exchange oveits by your own Docker Hub user name.

Now the image can be used by commands like e.g. docker run <options> <image> <CMD>

We now will create our first Jenkins Pipeline project.

Task: Create a Pipeline Workflow

1. On the Jenkins dashboard, select create new jobs under the Welcome message or *new Item in the sidebar menue.
2. Give the job a friendly name such as Pipeline Hello World, select Pipeline and press OK.
3. On the upper right corner of the Pipeline Script Textbox, find the drop-down menue try sample pipeline... and choose GitHub + Maven
4. Review the Groovy code. You will see that we will use git for cloning a sample project and we will build the project using the Maven installation we had named "M3".
5. Click Save

In the next step, we will try it out.

Note: the image has been created like follows:

docker run -d -u root --name jenkins \ -p 8080:8080 -p 50000:50000 \ --entrypoint bash \ jenkins:2.46.2-alpine \ -c "tail -F /jenkins.log"

docker exec -d jenkins \ bash -c 'git clone https://github.com/oveits/jenkins_home_alpine \ && export JENKINS_HOME=$(pwd)/jenkins_home_alpine \ && java -jar /usr/share/jenkins/jenkins.war 2>&1 1>/jenkins.log &'

Perform the manual steps 1 to 3.

docker stop jenkins docker commit jenkins newjenkinsimage

Create a new container with the correct entrypoint and CMD: docker run -d --entrypoint "bash" -p 8080:8080 -p 50000:50000 --name jenkins2 newjenkinsimage -c "JENKINS_HOME=/jenkins_home_alpine java -jar /usr/share/jenkins/jenkins.war"

For commiting the

docker stop jenkins2 docker login

Add your user credentials of Docker Hub here...

Then:

docker commit jenkins2 oveits/jenkins:2.46.2-alpine-nologin-with-maven-git-pipelines docker push oveits/jenkins:2.46.2-alpine-nologin-with-maven-git-pipelines

Here you need to exchange oveits by your own Docker Hub user name.

Now the image can be used by commands like e.g. docker run <options> <image> <CMD>

We now have a configured Pipeline job that will build our hello world software from Github. The next stage is to test and try it.

Task: Build

1. On the left-hand side, select Build Now. You should see that the pipeline is starting.

You can click on the Pipeline field, and you are offered to view the logs:

You will see, that there are some downloads running in the background, when running the build the first time:

1. Repeat the Build Now several times.

Some of the builds will be shown in green (stable), some will be shown in yellow (unstable). This comes from the fact, that the sample project we have chosen randomly throws errors, so we will get a nice Test Trend graph.

1. If you have started Jenkins in a separate Window or tab, reload the page or press F5. In the dashboard, you need to click on the Job name "Pipeline Hello World" instead.

Now a Test Result Trend will be shown:

SUCCESS!