Official Docker MongoDB Image of Synapsis
FROM syis/mongo:4.4.2-bionic
# An initialization script creates the needed
# databases by reading the environments named:
# - MONGO_DB_x_NAME
# - MONGO_DB_x_USER
# - MONGO_DB_x_PASSWORD
# (where x is an incremental integer)
# The script cycle over the numbers (by starting from 1),
# until it NOT find a variable named MONGO_DB_i_NAME
ENV MONGO_DB_1_NAME='db_name'
ENV MONGO_DB_1_USER='db_user'
ENV MONGO_DB_1_PASSWORD='db_password'
ENV MONGO_DB_2_NAME='db_2_name'
ENV MONGO_DB_2_USER='db_2_user'
ENV MONGO_DB_2_PASSWORD='db_2_password'
EXPOSE 27017