old_contents: import shipyard2.rules.pods
  
  shipyard2.rules.pods.define_pod(
      name='web-server',
      apps=[
          shipyard2.rules.pods.App(
              name='web-server',
              exec=[
                  'python3',
                  *('-m', 'http.server'),
                  *('--directory', '/srv/web'),
                  '8000',
              ],
          ),
      ],
      images=['//examples:web-server'],
  )
  
new_contents: import shipyard2.rules.pods
  
  UNIT_CONTENTS = '''\
  [Unit]
  Description=example web server
  
  [Service]
  ExecStart=/usr/local/bin/ctr pods run-prepared ${pod_id}
  
  [Install]
  WantedBy=multi-user.target
  '''
  
  shipyard2.rules.pods.define_pod(
      name='web-server',
      apps=[
          shipyard2.rules.pods.App(
              name='web-server',
              exec=[
                  'python3',
                  *('-m', 'http.server'),
                  *('--directory', '/srv/web'),
                  '8000',
              ],
          ),
      ],
      images=['//examples:web-server'],
      systemd_units=[
          shipyard2.rules.pods.SystemdUnit(
              name='web-server.service',
              contents=UNIT_CONTENTS,
          ),
      ],
  )
  
subject: Use the new systemd integration in example build rule