code: def add_spark_slave(self, master, slave, configure):
          
          # go to master server, add config
          self.reset_server_env(master, configure)
          with cd(bigdata_conf.spark_home):
              if not exists('conf/spark-env.sh'):
                  sudo('cp conf/spark-env.sh.template conf/spark-env.sh')
  
              spark_env = bigdata_conf.spark_env.format(
                  spark_home=bigdata_conf.spark_home,
                  hadoop_home=bigdata_conf.hadoop_home,
                  host=env.host_string,
                  SPARK_WORKER_MEMORY=configure[master].get(
                      'SPARK_WORKER_MEMORY', '512M'
                  )
              )
  
              put(StringIO(spark_env), 'conf/spark-env.sh', use_sudo=True)
  
              if not exists('conf/slaves'):
                  sudo('cp conf/slaves.template conf/slaves')
  
          # comment slaves localhost
          comment('{0}/conf/slaves'.format(bigdata_conf.spark_home),
                  'localhost', use_sudo=True)
  
          # add slave into config
          append('{0}/conf/slaves'.format(bigdata_conf.spark_home),
                 '\n{0}'.format(configure[slave]['host']), use_sudo=True)
  
          run('scp -r {0} {1}@{2}:/opt'.format(
              bigdata_conf.spark_home,
              configure[slave]['user'],
              configure[slave]['host']
          ))
  
          # go to slave server
          self.reset_server_env(slave, configure)
  
          append(bigdata_conf.global_env_home, 'export SPARK_LOCAL_IP={0}'.format(
              configure[slave]['host']
          ), use_sudo=True)
          run('source {0}'.format(bigdata_conf.global_env_home))
  
          # go to master server, restart server
          self.reset_server_env(master, configure)
          with cd(bigdata_conf.spark_home):
              run('./sbin/stop-master.sh')
              run('./sbin/stop-slaves.sh')
              run('./sbin/start-master.sh')
              run('./sbin/start-slaves.sh')
docs: add spark slave
          :return: