DRY Config for Docker build and App

Question

First off, this became a much longer post than I expected, tl;dr; How can I make my config DRY with docker (I'm assuming with env variables)

I am developing a node.js server with a mongodb database and I am switching over to docker to (hopefully) simplify my environment and keep it consistant for my server. Let me start out by saying that I definitely do not understand the entire docker-container life cycle, but I am learning as I go. I cannot find a solution to what I am trying to do after a lot of searching. I am using Docker for Windows with Hyper-V. (docker version at the bottom)

So, I would like to be able to configure

Database name
Database user
Database password
App port
and few other things

And allow these configured values to be used in several places including

Docker build phase (to setup database)
Node App (to connect to database)

What is the best way to be able to set the database name, user and pass, once and use it to initiate the database in the container, and then connect to it whenever the container is spun up?

Current Setup

Currently I have a docker-compose file that is the following (./docker-compose.yml)

version: "2"

services:
  myapp:
    image: node:boron
    volumes:
      - ./dist:/usr/src/app
    working_dir: /usr/src/app
    command: sh -c 'npm install; npm install -g nodemon; nodemon -e js app.js'
    ports:
      - "9021:9021"
    depends_on:
      - mongo
    networks:
      - all
  mongo:
    build: ./build/mongo
    networks:
      - all
networks:
  all:

Mongo Dockerfile (./build/mongo/Dockerfile)

# Image to make this from
FROM mongo:3

# Add files into the container for db setup
ADD initDB.js /tmp/
ADD createDBAdmin.js /tmp/
ADD mongod.conf /data/configdb

# Map the host directory mongo/myapp to /data
VOLUME /mongo/myapp:/data    

RUN ls /data/*

RUN mongod -f /data/configdb/mongod.conf && sleep 5 && mongo ${DB_NAME} /tmp/createDBAdmin.js && sleep 5 && mongo ${DB_NAME} /tmp/initDB.js


CMD mongod --smallfiles --storageEngine wiredTiger

The initDB.js script (./build/mongo/initdb.js)

db.createUser(
    {
      user: "${DB_USER}",
      pwd: "${DB_PASS}",
      roles: [
        { role: "dbOwner", db: "${DB_NAME}" }
      ]
    },
    {
      w: "majority",
      wtimeout: 5000
    }
);
// For some reason this is needed to save the user
db.createCollection("test");

docker version

Client:
 Version:      1.13.0
 API version:  1.25
 Go version:   go1.7.3
 Git commit:   49bf474
 Built:        Tue Jan 17 21:19:34 2017
 OS/Arch:      windows/amd64

Server:
 Version:      1.13.0
 API version:  1.25 (minimum version 1.12)
 Go version:   go1.7.3
 Git commit:   49bf474
 Built:        Wed Jan 18 16:20:26 2017
 OS/Arch:      linux/amd64
 Experimental: true

Extra credit How can I persist database information outside of the container for backup purposes etc. and view the files? Do I need to map a directory on my host machine to data/db in the container and am i doing this correctly?

EDIT: This seems to be a good solution to the "Extra credit" question. How to deal with persistent storage (e.g. databases) in docker

DRY Config for Docker build and App

0 Answers0