Docker with Jenkins Plugins

At times you might want to add have a version of Jenkins that automatically has a predefined set of plugins installed .

You might want to find an existing jenkins with all the installed plugins assume the url is http://myjenkinshostname/jenkins to get the list of plugins you might need.

Navigate to http://myjenkinshostname/jenkins/script  there you want to past the following codes and execute :

def plugins = jenkins.model.Jenkins.instance.getPluginManager().getPlugins() plugins.each {println "${it.getShortName()}: ${it.getVersion()}"}


There are other ways to also get the  list of plugins , check this site .

You would then create a docker file where you define all these necessary e.g

===Dockerfile==================
FROM jenkins/jenkins:lts

ENV JENKINS_OPTS --prefix=/jenkins
RUN /usr/local/bin/install-plugins.sh  aws-credentials amazon-ecr amazon-ecs pipeline-maven

==========================

When the docker container is initialised this will automatically install all the plugins you define within it.

Apparently there is a way to all install tools directly through a groovy script as mentioned on the official github repo for jenkins but I have yet to try it .

This list of scripts might then be interesting to try out for automatic installation of tools e.g to automatically install a specific version of maven .

Automatic Install of Maven with Jenkins and use within Pipeline

Assume you want a specific version of  Maven to be installed automatically when doing a build e.g because you need to have a build executed on a remote node.

This is what you need to do to perform this :

• Install the following 2 plugins on your Jenkins 2x instance ( if not already preseent :
• Config File Provider - https://wiki.jenkins-ci.org/display/JENKINS/Config+File+Provider+Plugin 
• Pipeline Maven Plugin - https://wiki.jenkins-ci.org/display/JENKINS/Pipeline+Maven+Plugin 
• Restart your Jenkins such as the Plugins can take effect
• Define your settings.xml file within  Jenkins > Manage Jenkins > Managed Files
• Click on Add a new Config
• choose Global Maven settings 
• choose a valid id name e.g GlobalMavenSettingsForXXX
• copy paste the settings.xml of your project on next page
• Note the settings.xml should allow you to get your plugins and dependencies from your repositories

• Define your Maven tool within the menu Jenkins > Manage Jenkins > Global Tool Configuration page
• Click on Maven Installations
• Specify name for your maven 
• Specify maven home directory e.g /usr/local/maven-3.2.5
• Check the Automatic install option
• Choose Install from Apache e.g maven-3.2.5

• Make sure that you Jenkins has access to install Maven within your maven home directory by executing the following command (on your slave ):
• sudo chmod -R ugo+rw /usr/local/maven-3.2.5

• Now you can use maven in your Jenkins pipeline using a command such as :

withMaven(globalMavenSettingsConfig: 'maven-atlas-global-settings', jdk: 'JDK6', maven: 'M3_3.2.5', mavenLocalRepo: '/home/ubuntu/.m2/repository/') {

   

           sh 'mvn  clean install ' 

            

        }

Note that you can use the Pipeline Syntax helper to fill the options you want to use with Maven .

Publish Docker Image to Amazon ECR

If you are using an Amazon AWS chances are that you already have ECR , Amazon EC2 Container Registry , within your account . Now this is practical if you want to have you own private Docker Registry for saving your docker images .

Now in my case I wanted to be able to push an image to my private Registry within the context of a Jenkins build .

So we will need to do the following  :

• Configure AWS credentials on build machine
• Configure Amazon ECR Docker Registry
• Modify our Jenkins pipeline to perform a push 

Configure AWS credentials on build machine

1. install the awscli which allows you then to configure your aws account login info on your env , this is done using :

sudo apt install awscli

2. next we do the aws configuration using the following command, ( see AWS CLI official guide  ):

aws configure

Here you will need to know your AWS Access Key ID and AWS Secret Access Key .

Note that the Secret Access Key ID is generated only once , so you need to keep it somewhere safe or regenerate a new one .

To get the 2 keys you would need to login to your AWS console and go to :

IAM > Users > Now select one of the users > Click on Security Credentials tab >  Now from here you can create a New Access Key 

Configure Amazon ECR Docker Registry

1. Login to your AWS console  .

2. Choose "EC2 Container Service"

3. Click on Repositories > Create Repository

4. Set a name for your repository 

5. Clicking on next will give you all the commands to login to ECR from aws cli , tag and push your image to your repo

For reference the official link to ECR is here .

Modify our Jenkins pipeline to perform a push

 Now that we have aws login configured on build machine and a private docker registry on Amazon we are ready to modify our Jenkins pipeline to perform the push .

Here I assume that you already do have Jenkins job existing and you know your way through the pipeline goovy codes .

So we will add the following :

{

....

}

stage('Publish Docker Image to AWS ECR '){

       

        def loginAwsEcrInfo = sh(returnStdout: true, script: 'aws ecr get-login --region us-east-1').trim()

        echo "Retreived AWS Login: ${loginAwsEcrInfo}"

        

        sh '${loginAwsEcrInfo}' 

        sh 'docker tag tomcat6-atlas:latest XXXXXXXXXXXX.YYY.ZZZ.us-east-1.amazonaws.com/tomcat6-atlas:latest'

        sh 'docker push XXXXXXXXXXXX.YYY.ZZZ.us-east-1.amazonaws.com/tomcat6-atlas:latest'

       

   }

Note: Do replace the tag and push command with the actual values as indicated from your Amazon ECR repository page

Notice that I have a loginAwsEcrInfo variable defined in grovy , this is because I need to get the output of the command ' aws ecr get-login --region us-east-1 ' from sh which actually generates the command to login through docker using the aws credentials . This is possible thanks to the returnStdout flag on sh .

That should be it , you should be able to publish your image within your Jenkins job execution .