Adel Bordbari

Dynamic Settings in Django (Revisited)

Table of Contents

Situation

Sometimes, the need arises for application-level settings to be configurable at runtime — without redeployments or code edits. In our Django setup, we wanted admin users to define or modify settings such as session expiration time or Metabase dashboard refresh intervals. These changes should propagate to the settings.py file so that other parts of the project relying on django.conf.settings can access them.

Problem

Django loads the settings.py at startup, and changes to this file don’t take effect until the server restarts. Simply put, unlike templates or URLs, there is no built-in live reloading mechanism for Python settings.

We needed a way to:

  1. Store new or updated key-value settings from a form.
  2. Persist these in the database.
  3. Reflect them inside settings.py.
  4. Restart the Django server automatically.

Investigation

We reviewed several libraries:

While they provide models and admin interfaces for preferences, they either don’t reflect settings in django.conf.settings or require custom logic to do so — which still doesn’t help when a hard setting like SESSION_EXPIRE_SECONDS needs to live in settings.py.

Additionally, circular import issues block you from directly referencing database models from within settings.py.

Solution

We created a custom implementation using:

Key Components

Model

class CustomSettings(models.Model):
    name = models.CharField(max_length=255, unique=True)
    value = models.CharField(max_length=255)

Form

class CustomSettingsForm(forms.ModelForm):
    class Meta:
        model = CustomSettings
        fields = ["name", "value"]

Writing to settings.py

def update_settings_file():
    settings_path = os.path.abspath(importlib.import_module("mainApp.settings").__file__)
    custom_settings = CustomSettings.objects.all()
    
    with open(settings_path, "r") as f:
        lines = f.readlines()

    start = end = None
    for i, line in enumerate(lines):
        if "# Custom settings start" in line: start = i
        if "# Custom settings end" in line: end = i

    if start is not None and end is not None:
        del lines[start:end + 1]

    new_lines = ["# Custom settings start
"]
    for setting in custom_settings:
        new_lines.append(f"{setting.name.upper()} = {format_value(setting.value)}
")
    new_lines.append("# Custom settings end
")

    lines = lines[:start] + new_lines + lines[start:] if start is not None else lines + new_lines

    with open(settings_path, "w") as f:
        f.writelines(lines)

Restarting Server

def restart_server():
    os.execl(sys.executable, sys.executable, *sys.argv)

This restarts the Django server by replacing the current process with a fresh one.

Form Handling

We handled multiple forms in the same view using button names and/or hidden inputs:

if "custom" in request.POST:
    ...
elif "session" in request.POST:
    ...

This lets us handle each form differently based on what button was clicked.

Final settings.py Snippet

SESSION_EXPIRE_MINUTES = 15 # this is basically how we set default values

# Custom settings start

# this is where django writes the name-value pairs

# Custom settings end

SESSION_EXPIRE_SECONDS = SESSION_EXPIRE_MINUTES * 60 # post-processing if needed

This ensures there’s always a fallback value, and the real value is updated when the section is rewritten dynamically.

Takeaways