Dockerfile cookbook¶

Different idioms and recipes for writing dockerfiles.

Table of Contents¶

Using throwaway containers
Running multiple processes in a single container
Discussions
1. ENTRYPOINT vs CMD
2. Good practices
docker-compose
1. MongoDB with MongoExpress

Using throwaway containers¶

Consider having a Vue website, which you want to serve with a flask backend. Creating a container with both Vue and Flask executables would be highly bloated: instead, we can use throwaway containers to build different aspects of our project, and copy them into the final container:

FROM node:current-alpine3.11 AS installer

# fetch or copy in the source code for javascript

RUN npm i . && npm run build

FROM python:3.8.5-slim-buster
COPY --from=installer /dist /web

RUN pip install -r requirements.txt

CMD ["flask", "run", "-h", "0.0.0.0", "-p", "8080"]

EXPOSE 8080

Here, the node:current-alpine3.11 container is aliased installer and is not bundled into our final python:3.8.5-slim-buster container, reducing the final size, and not shipping unneeded executables.

Running multiple processes in a single container¶

This follows from a suggestion in the docker documentation. I personally have had most success with supervisord, which I will write separate notes for available here.

The dockerfile only requires to copy in configurations and then set the entry-point

COPY 
supervisord.conf /etc/supervisor/conf.d/supervisord.conf
CMD ["/usr/bin/supervisord"]

NB: in the supervisord.conf ensure you have

[supervisord]
nodaemon=true

for the supervisor configuration set.

Discussions¶

`ENTRYPOINT` vs `CMD`¶

TODO

Good practices¶

TODO

docker-compose¶

Recipes for docker-compose.

MongoDB with MongoExpress¶

version: "3.8"

# Docker compose file for starting only the database environment for development

services:
    mongodb:
        image: mongo
        ports:
            - 27017:27017
            - 28017:28017
        volumes:
            - ./store:/data/db
        networks:
            - asteroid

    mongo_express:
        image: mongo-express
        ports:
            - 8081:8081
        environment:
            - ME_CONFIG_MONGODB_SERVER=mongodb
            - ME_CONFIG_MONGODB_PORT=27017
        networks:
            - asteroid
        depends_on:
            - mongodb
        restart: always

networks:
    asteroid:

notes

Dockerfile cookbook

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