This is newrelic clouc-config.yml for pxeboot coreos. https://registry.hub.docker.com/u/uzyexe/newrelic

newrelic-for-pxeboot-coreos-cloud-config.yml

coreos:
  units:
    - name: docker.service
      command: restart
      content: |
          [Unit]
          Description=Docker Application Container Engine
          Documentation=http://docs.docker.io
          
          [Service]
          Environment="TMPDIR=/var/tmp/"
          ExecStartPre=/bin/mount --make-rprivate /
          ExecStart=/usr/bin/docker -d -r=false -H fd://
          
          [Install]
          WantedBy=multi-user.target
    - name: newrelic-client.service
      command: start
      content: |
          [Unit]
          Description=newrelic-client
          
          [Service]
          Restart=always
          EnvironmentFile=/etc/environment
          TimeoutStartSec=20m
          ExecStart=/bin/bash -c 'HOSTNAME=`/usr/bin/hostname`; docker run --name newrelic-client --rm --env="NEW_RELIC_LICENSE_KEY=YOUR_NEW_RELIC_LICENSE_KEY" -h $HOSTNAME uzyexe/newrelic'
          ExecStop=/usr/bin/docker kill newrelic-client