The official Steemit/Steem:latest Dockerfile image uses the config file config-for-docker.ini which only enables a select few plugins. This image adds the fullnode.config.ini plugins to the config-for-docker.ini
plugin = webserver p2p json_rpc witness account_by_key reputation tags follow market_history account_history
plugin = database_api account_by_key_api network_broadcast_api reputation tags_api follow_api market_history_api condenser_api account_history_api rc_api condenser_api block_apihttps://github.com/steemit/steem/blob/master/contrib/config-for-docker.ini
https://github.com/steemit/steem/blob/master/contrib/fullnode.config.ini