Docker: Multiple Dockerfiles in project

Question

How do you organize the Dockerfiles belonging to a project when you have one Dockerfile for the database, one for the application server, and so on? Do you create some sort of hierachy in the source? A big enterprise project can't consist of only one Dockerfile?

Answer 1

In newer versions(>=1.8.0) of docker, you can do this

docker build -f Dockerfile.db .
docker build -f Dockerfile.web .

A big save.

EDIT: update versions per raksja's comment

EDIT: comment from @vsevolod: it's possible to get syntax highlighting in VS code by giving files .Dockerfile extension(instead of name) e.g. Prod.Dockerfile, Test.Dockerfile etc.

Answer 2

Use docker-compose and multiple Dockerfile in separate directories

Don't rename your Dockerfile to Dockerfile.db or Dockerfile.web, it may not be supported by your IDE and you will lose syntax highlighting.

As Kingsley Uchnor said, you can have multiple Dockerfile, one per directory, which represent something you want to build.

I like to have a docker folder which holds each applications and their configuration. Here's an example project folder hierarchy for a web application that has a database.

docker-compose.yml
docker
├── web
│   └── Dockerfile
└── db
    └── Dockerfile

docker-compose.yml example:

version: '3'
services:
  web:
    # will build ./docker/web/Dockerfile
    build: ./docker/web
    ports:
     - "5000:5000"
    volumes:
     - .:/code
  db:
    # will build ./docker/db/Dockerfile
    build: ./docker/db
    ports:
      - "3306:3306"
  redis:
    # will use docker hub's redis prebuilt image from here:
    # https://hub.docker.com/_/redis/
    image: "redis:alpine"

docker-compose command line usage example:

# The following command will create and start all containers in the background
# using docker-compose.yml from current directory
docker-compose up -d

# get help
docker-compose --help

In case you need files from parent folder(s) as part of the build context of your Dockerfile

You can still use the above solution and place your Dockerfile in a directory such as docker/web/Dockerfile, all you need is to set the build context in your docker-compose.yml like this:

version: '3'
services:
  web:
    build:
      context: .
      dockerfile: ./docker/web/Dockerfile
    ports:
     - "5000:5000"
    volumes:
     - .:/code

The files hierarchy would loke like this:

config-on-root.ini
docker-compose.yml
docker
└── web
    ├── Dockerfile
    └── some-other-config.ini

The ./docker/web/Dockerfile will have access to desired files from the context like this:

FROM alpine:latest

COPY config-on-root.ini /
COPY docker/web/some-other-config.ini /

Also note that the build context will contain all the files of the specified directory. Make sure tou use a .dockerignore file to prevent loading undesired large files or directories to save time during build.

Here are some quick commands from tldr docker-compose. Make sure you refer to official documentation for more details.

Answer 3

Author's Note

This answer is out of date. Fig no longer exists and has been replaced by Docker compose. Accepted answers cannot be deleted.

Docker Compose supports the building of project hierachy. So it's now easy to support a Dockerfile in each sub directory.

├── docker-compose.yml
├── project1
│   └── Dockerfile
└── project2
    └── Dockerfile

---

Original answer

I just create a directory containing a Dockerfile for each component. Example:

• Setting up a docker / fig Mesos environment

When building the containers just give the directory name and Docker will select the correct Dockerfile.

Answer 4

In Intellij, I simply changed the name of the docker files to *.Dockerfile, and associated the file type *.Dockerfile to docker syntax.

Answer 5

Add an abstraction layer, for example, a YAML file like in this project https://github.com/larytet/dockerfile-generator which looks like

centos7:
    base: centos:centos7
    packager: rpm
    install:
      - $build_essential_centos 
      - rpm-build
    run:
      - $get_release
    env:
      - $environment_vars

A short Python script/make can generate all Dockerfiles from the configuration file.

Answer 6

When working on a project that requires the use of multiple dockerfiles, simply create each dockerfile in a separate directory. For instance,

app/ db/

Each of the above directories will contain their dockerfile. When an application is being built, docker will search all directories and build all dockerfiles.