MDBF-423: Change default connection to database to use host different than dock…

[an3l]

…er container

• After setting up the virtual environment for the project
  (note missing instruction how to work locally with venv in Readme.md) and
  after running the makemigrations --dry-run or starting the webserver,
  application is trying to connect with hardcoded hostname db used from Dockerfile
• This patch allows to add multiple hostname from environment variable separed
  by delimiter (I liked ,) and since the create type in settings.py is list type
  it is free to use first value from a list.
• Proof

• No patch

$ export DJANGO_ALLOWED_HOSTS=localhost,127.0.0.1
$ ./manage.py makemigrations --dry-run
/home/anel/mariadb/feedback-plugin-backend/env/lib/python3.8/site-packages/django/core/management/commands/makemigrations.py:105:
  RuntimeWarning: Got an error checking a consistent migration history performed for database connection 'default': (2005, "Unknown MySQL server host 'db' (-3)")
  warnings.warn(
Migrations for 'feedback_plugin':
  feedback_plugin/migrations/0002_alter_rawdata_upload_time.py
    - Alter field upload_time on rawdata

• With patch

$ ./manage.py makemigrations --dry-run
Migrations for 'feedback_plugin':
  feedback_plugin/migrations/0002_alter_rawdata_upload_time.py
    - Alter field upload_time on rawdata

• Also server gets started correctly

$ ./manage.py runserver
Performing system checks...

System check identified no issues (0 silenced).

You have 19 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, feedback_plugin, sessions.
Run 'python manage.py migrate' to apply them.
May 30, 2022 - 14:51:50
Django version 3.2.13, using settings 'feedback_plugin.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

[grooverdan]

DJANGO_ALLOWED_HOSTS and the database host are actually different concepts. Why not os.environ['DJANGO_DB_HOST']

[cvicentiu]

@an3l I like the first change where one allows multiple hosts in DJANGO's allow hosts.
I am ok with having a change-able db host via an environment variable. You can do as Daniel suggests, but please also update

docker/.env file if you do so.

[an3l]

Ok based on documentation allowed_host is used for other purposes (may be empty when DEBUG=true).
Django documentation for setting up MySQL has an example of usage of configuration file in options over NAME, HOST, etc , however I don't want to write the tweaks to populate configuration file with variable parameters like environment databases.
Have updated the patch @cvicentiu

[an3l]

Based on #8 it seems that one need to have docker_db_1 as an default host based on the docker_default network and if needed user need to change manually to localhost (or empty string), atm I don't know other solution to have defaults both for container and host as localhost.
Instead when using locally this will be interpreted as an localhost, but when using in a container empty string will use socket in web_1 container and the host will not be visible, ever.

[an3l]

Based on #8 it seems that one need to have docker_db_1 as an default host based on the docker_default network

[an3l]

The same is here ^^^
Based on #8 it seems that one need to have docker_db_1 as an default host based on the docker_default network
Instead when using locally this will be interpreted as an localhost, but when using in a container empty string will use socket in web_1 container and the host will not be visible, ever.
This will need to update.

[cvicentiu]

Closing this as currently the deployment relies on docker-compose for full stack deployment. We will make these changes when we need to have a DB run on a different host.

We will keep using square brackets for environment variable fetching to highlight bugs. If an environment variable is missing, we want the code to throw an error, not silently continue.