A `bash` function for running the Jenkins CI LTS image as a docker process.

jenkins_on_docker.sh

function jenkinsondocker() {
    if [ $(ps -elf | grep docker | wc -l) -gt 0 ];
    then
        if [ "$1" == "clean" ] || [ "$2" = "clean" ]; then
            echo "# $(date) Removing any previously running Jenkins instances..."
            echo Stopping $(docker stop jenkins 2>&1) | sed 's/Error response from daemon://'
            echo Removing $(docker rm jenkins 2>&1)   | sed 's/Error response from daemon://'
        fi

        docker pull jenkins/jenkins:lts
        docker run --detach --publish 49000:8080 --name jenkins jenkins/jenkins:lts || return

        # The container must be running before Jenkins can be configured
        if [ "$1" == "configure" ] || [ "$2" = "configure" ]; then

            # configure jenkins
            echo "# $(date) Configuring Jenkins..."
            docker exec --user root jenkins bash -c "apt update && apt install wget && which wget"

            ## skip the installation wizard at startup
            echo "# $(date) Skipping the installation wizard on first boot..."
            docker exec --user root jenkins bash -c "echo 'JAVA_ARGS=\"-Djenkins.install.runSetupWizard=false\"' >> /etc/default/jenkins"

            ## download the list of plugins
            echo "# $(date) Downloading the list of plugins..."
            docker exec --user root jenkins wget https://raw.githubusercontent.com/jenkinsci/jenkins/master/core/src/main/resources/jenkins/install/platform-plugins.json

            ## get the suggested plugins
            echo "# $(date) Using the keyword 'suggest' to find the suggested plugins in the list..."
            docker exec --user root jenkins bash -c 'grep suggest platform-plugins.json | cut -d\" -f 4 | tee suggested-plugins.txt'

            ## download the plugin installation tool
            echo "# $(date) Downloading the plugin installation tool"
            docker exec --user root jenkins bash -c 'wget https://github.com/jenkinsci/plugin-installation-manager-tool/releases/download/2.12.3/jenkins-plugin-manager-2.12.3.jar'

            ## run the plugin installation tool
            echo "# $(date) Running the plugin installation tool..."
            docker exec --user root jenkins bash -c '/usr/bin/env java -jar ./jenkins-plugin-manager-2.12.3.jar \
                --verbose \
                --plugin-download-directory=/var/jenkins_home/plugins \
                --plugin-file=./suggested-plugins.txt | tee /var/log/plugin-installation.log'

            # The container must be restarted to pick up the new configuration
            echo "# $(date) Restarting Jenkins container..."
            docker restart jenkins
        fi

        echo -n "# $(date) Waiting for Jenkins process to start ."
        until [ $(curl -o /dev/null --silent --head --write-out '%{http_code}\n' http://127.0.0.1:49000) -eq 403 ]; do
            echo -n '.';
            sleep 1;
        done

        ADMIN_PASS=$(docker exec jenkins cat /var/jenkins_home/secrets/initialAdminPassword)

        echo
        echo
        echo
        echo "Jenkins URL:"
        echo "    http://localhost:49000"
        echo
        echo "Admin password:"
        echo "    ${ADMIN_PASS}"
        echo
        echo "To run commands in the container as root:"
        echo "    docker exec --user root -it jenkins bash"

    else
        echo "Can't find any docker processes.  Is Docker really running? :("
    fi
}