Add docker-compose support

[LivingWithHippos]

Start your LinkDing instance with docker-compose up -d
It still needs the docker exec -it linkding python manage.py createsuperuser --username=joe --email=joe@example.com command, it would be nice to automate it using a .env file

It probably should be mentioned in the README, too.

[sissbruecker]

@LivingWithHippos Good idea 👍, but I think it could use some improvements to make it easier to use.

1. The docker-compose config file is currently more of a template (especially the volume configuration), it would make sense to make it configurable so that it can be used out-of-the-box without having to change the docker-compose file itself and setting yourself up for future merge conflicts. I think using an .env file is the appropriate way to do this. I would suggest adding an .env.dist file which defines all necessary variables (port and volume path so far) and contains default values. Users can then clone the repo, copy the .env.dist to .env and make changes to it. Then just run docker-compose up -d. .env should be added to .gitignore.
2. There should be a README section which explains how to use this.

[LivingWithHippos]

I mistakenly deleted my fork so I think I'll have to close this PR and open another one

So, following the names already in use

• LD_CONTAINER_NAME for the container_name
• LD_HOST_PORT for the port
• LD_HOST_DATA_DIR for the data dir

Anyway in the meawhile we can discuss this here

docker-compose.yml with default values included (this will work both with and without a .env file)

version: '3'

services:
  linkding:
    container_name: "${LD_CONTAINER_NAME:-linkding}"
    image: sissbruecker/linkding:latest
    ports:
      - "${LD_HOST_PORT:-9090}:9090"
    volumes:
      - "${LD_HOST_DATA_DIR:-./linkding_data}:/etc/linkding/data"
    restart: unless-stopped

.env.sample with default values included

LD_CONTAINER_NAME=linkding
LD_HOST_PORT=9090
LD_HOST_DATA_DIR=/etc/linkding/data

Since all the values are "external" I don't think a .env.prod/dev is needed (or a .env at all), maybe if some values that are added to the environment section of the compose in the future it could be more useful

[sissbruecker]

@LivingWithHippos That looks very good, would you like to open a new PR?

Icing on the cake would be to add a section to the README.md that quickly explains how to use this with docker-compose (start command) and how a .env file can be used to configure the setup 😉

[LivingWithHippos]

replaced by #54