Create config source. 

cat << EOF > toolconfig.env
UAT_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL=http://uat-content-management-server:8080/ior
UAT_MASTER_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
UAT_REPLICATION_1_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
UAT_REPLICATION_2_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
# PROD
PROD_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL=http://prod-content-management-server:8080/ior
PROD_MASTER_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
PROD_REPLICATION_1_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
PROD_REPLICATION_2_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
EOF

Export content to your host from UAT content-management-server. 

docker run --rm \
  --env-file=toolconfig.env \
  -e CONFD_PREFIX=uat/management \
  --volume $PWD/export:/export \
  coremedia/management-tools confd \
  tools/bincm serverexport -u admin -p admin \
  -r --basedir /export /

In the example above we pass the toolconfig.env to docker and set the environment variable CONFD_PREFIX to uat/management, which translates to the environment variable prefix UAT_MANAGEMENT_. In our env file we defined the connection to the content-management-server using the key UAT_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL. If we had set the prefix to uat/master we would have used the contentrepository of the master for the export.