Você deve começar mongod em primeiro lugar.
FROM mongo:2.6
MAINTAINER Living Digital Way
COPY ./init.ms .
# assume you are in mongo bin directory
RUN mongod -f you-config-path/mongo.conf
RUN mongo < ./init.ms
FROM mongo:2.6
MAINTAINER Living Digital Way
COPY ./init.ms .
# assume you are in mongo bin directory
RUN mongod -f you-config-path/mongo.conf
RUN mongo < ./init.ms