Dockerfile and docker-compose.yaml for different environments - docker

Question

docker-compose for prod:
version: '2'
services:
db:
image: mongo:3
ports:
- "27017:27017"
api-server:
build: .
ports:
- "443:443"
links:
- db
volumes:
- /www/node_modules
Dockerfile for prod:
FROM alpine:3.4
LABEL authors="John Doe"
RUN apk add --update nodejs bash git
COPY package.json /www/package.json
RUN cd /www; apk --no-cache add --virtual builds-deps build-base python && npm install && npm rebuild bcrypt --build-from-source && apk del builds-deps
COPY . /www
WORKDIR /www
ENV PORT 8080
EXPOSE 8080
CMD ["npm", "start"]
docker-compose for dev:
version: '2'
services:
db:
image: mongo:3
ports:
- "27017:27017"
api-server:
build: .
ports:
- "8080:8080"
links:
- db
volumes:
- .:/www
- /www/node_modules
Dockerfile for dev
FROM alpine:3.4
LABEL authors="John Doe"
RUN apk add --update nodejs bash git
COPY package.json /www/package.json
RUN cd /www; apk --no-cache add --virtual builds-deps build-base python && npm install && npm rebuild bcrypt --build-from-source && apk del builds-deps
WORKDIR /www
ENV PORT 8080
EXPOSE 8080
CMD ["npm", "run", "dev"]
I'm running it with docker-compose up.
Right now i have to manually make changes to files in order to change environment, which is, of course, wrong way to do this.
I assume there should be a way to avoid these manual changes. How do i do that?

Answer 1

You can specify environment in the services part of the docker-compose.yml file.
Example:
services:
environment:
NODE_ENV: "development"
APP_PORT: 5000
DB_URI: "<DB URI>"
And in your code, you can take these values by specifying process.env.NODE_ENV

Answer 2

Dockerfile should contain the commands for creating the image. That image when used with docker-compose api-server service of yours will run the server as required.
For eg., in your case:
Your Dockerfile should look something like this.
FROM alpine:3.4
LABEL authors="John Doe"
RUN apk add --update nodejs bash git
RUN mkdir /www
WORKDIR /www
ADD package.json /www/package.json
RUN apk --no-cache add --virtual builds-deps build-base python && npm install && npm rebuild bcrypt --build-from-source && apk del builds-deps
This will create your image.
regarding your docker-compose.yml file, use two separate docker-compose files for both production and development. Use env files to separate out development and production variables. you can check in the development docker-compose.yml and development env file in your repository, production docker-compose and environment files will be specific to your production server.
Your sample docker-compose.yml file should look something like this
version: '2'
services:
db:
image: mongo:3
ports:
- "27017:27017"
api-server:
build:
context: .
dockerfile: Dockerfile
ports:
- "8080:8080"
links:
- db
env_file:
development.env
volumes:
- ./:/www
- /www/node_modules # I really don't understand this statement
command: >
/bin/ash -c "npm run dev"
This will be running your development server.
Similarly a same docker-compose.yml file with different ports exposed for production -443:443 in your case and env_file to production.env and command set to /bin/ash -c "npm start" will help run your production server.
version: '2'
services:
db:
image: mongo:3
ports:
- "27017:27017"
api-server:
build:
context: .
dockerfile: Dockerfile
ports:
- "443:443"
links:
- db
env_file:
production.env
volumes:
- ./:/www
- /www/node_modules # I really don't understand this statement
command: >
/bin/ash -c "npm start"
In case you are running the development server and production server (never advisable) in the same machine you can create two files named docker-compose-development.yml and docker-compose-production.yml for development and production systems respectively and then you can run the server by using the command:
sudo docker-compose -f docker-compose-development.yml up
sudo docker-compose -f docker-compose-production.yml up
for development and production system respectively.

Answer 3

you can use environment variables as
for example
set env as export env="prod" in you local machine terminal
and in docker-compose-file
image: container_image_${env} or image: container_image:${env}
will create images as container_image_prod or container_image:prod
you can also set the service name for db as db_${env} so that you get the service name according to the environment as db_prod in this case similarly you can do for other services if required