Django Helpers

Provides a series of helpers to provide a consistent experience across PHAC-ASPC's Django based projects.

Third party applications

By using this library, the following django applications will automatically be added to your django project:

• django-axes
• django-environ
• django-modeltranslation
• django-structlog

Quick start

pip install django-phac_aspc-helpers

# settings.py

from phac_aspc.django.settings.utils import configure_apps, configure_middleware
from phac_aspc.django.settings import *

INSTALLED_APPS = configure_apps([...])
MIDDLEWARE = configure_middleware([...])

Note Replace [...] above with the corresponding existing configuration from your project.

The configure_apps and configure_middleware utility functions will insert the appropriate applications into their correct location in your project's application and middleware lists.

# urls.py

from  phac_aspc.django.helpers.urls import urlpatterns as phac_aspc_helper_urls

urlpatterns = [
    ...
    *phac_aspc_helper_urls,
]

Note Add *phac_aspc_helper_urls to the list or urlpatterns exported by your project's urls module.

Jinja

If you are using jinja, you can use the phac_aspc jinja utils and django templatetags by adding them to the global environment like this:

import phac_aspc.django.helpers.templatetags as phac_aspc
import phac_aspc.django.helpers.jinja_utils as include_from_dtl


def environment(**options):
    env = Environment(**options)
    env.globals.update({
       "phac_aspc": phac_aspc,
       "include_from_dtl": include_from_dtl,
    })
    return env

For more information, refer to the Jinja documentation.

Environment variables

Several settings or behaviours implemented by this library can be controlled via environment variables. By default, these environment variables are read from the .env file in your project's root. This is done via the django-environ library; refer to their documentation on how to format special data types like lists.

Alternatively, these environment variables can be declared in your settings.py itself. There are two important caveats when doing so:

1. settings.py declarations take precedence over any instances of the same env var in your .env file
2. any env vars declared in settings.py for this library must be declared before any imports from phac_aspc occur!
   • similarly, you should not consumephac_aspc modules anywhere that executes prior to Django's consumption of your app's settings module (e.g. in manage.py)
   • phac_aspc modules that don't, directly or indirectly, depend on these env vars are theoretically safe anywhere, but we don't currently identify these modules, or make promises that any given module won't start depending on env vars in the future

All env vars for this library are prefixed with PHAC_ASPC_. Available PHAC_ASPC_ env vars are listed under their coresponding "feature" sections below.

global_from_env

This library also provides a utility that automatically declares an un-prefixed module level global from a prefixed env var. It is particularly useful when declaring django settings. The default prefix used is PHAC_ASPC_

from phac_aspc.django.settings.utils import global_from_env

global_from_env(
    SESSION_COOKIE_AGE=(int, 1200),
)

The example above creates the module level global SESSION_COOKIE_AGE taking the value of the env var named PHAC_ASPC_SESSION_COOKIE_AGE, defaulting to 1200 if no env var is found. As with other configuration env vars for this library, the value can either come from Django settings or from a .env file.

An alternative prefix can also be provided as well, to use this with other env var name spaces.

from phac_aspc.django.settings.utils import global_from_env

global_from_env(
    prefix='MY_PREFIX_',
    SESSION_COOKIE_AGE=(int, 1200),
)

Features

Web Experience Toolkit (WET)

The Web Experience Toolkit is bundled with the helpers, and can easily be added to your templates.

Your base template should be modified to:

• Specify the current language in the lang attribute of the HTML element
• Include the WET CSS files inside the HEAD element
• Include the WET script files at the end of your BODY element

A minimum base template may look like this:

{% load phac_aspc_wet %}
{% load phac_aspc_localization %}
<html lang="{% phac_aspc_localization_lang %}">
    <head>
        {% phac_aspc_wet_css %}
    </head>
    <body>
        <h1>Minimum base template</h1>
        {% block content %}{% endblock %}
        {% phac_aspc_wet_scripts %}
    </body>
</html>

or if you're using Jinja:

<html lang="{{ phac_aspc.phac_aspc_localization_lang() }}">
    <head>
        {{ phac_aspc.phac_aspc_wet_css() }}
    </head>
    <body>
        <h1>Minimum base template</h1>
        {% block content %}{% endblock %}
        {{ phac_aspc.phac_aspc_wet_scripts() }}
    </body>
</html>

Bundled WET releases

Product	Version
Web Experience Toolkit (WET)	v4.0.56.4
Canada.ca (GCWeb)	v12.5.0

Sign in using Microsoft

By adding a few environment variables, authentication using Microsoft's identity platform is automatically configured via the Authlib library. Setting the PHAC_ASPC_OAUTH_PROVIDER variable to "microsoft" enables OAuth and adds the following new routes:

• /en-ca/phac_aspc_helper_login (phac_aspc_helper_login)
• /fr-ca/phac_aspc_helper_login (phac_aspc_helper_login)
• /en-ca/phac_aspc_helper_authorize (phac_aspc_authorize)
• /fr-ca/phac_aspc_helper_authorize (phac_aspc_authorize)

The phac_aspc_authorize URLs above must be added to the list of redirect URLs in the Azure App Registration.

The login flow is triggered by redirecting the browser to the named route phac_aspc_helper_login. The browser will automatically redirect the user to Microsoft's Sign in page and after successful authentication, return the user to the redirect route named phac_aspc_authorize along with a token containing information about the user.

By default, the authentication backend will look for a user who's username is the user's uuid from Microsoft - if not found a new user is created. To customize this behaviour, a custom authentication backend class can be specified via PHAC_ASPC_OAUTH_USE_BACKEND in settings.py.

After successful authentication, the user is redirected to /. To customize this behaviour, set PHAC_ASPC_OAUTH_REDIRECT_ON_LOGIN in settings.py to the name of the desired route.

Redirecting to a specific page is also supported through the ?next=<url> query parameter. See "Template Tag" examples below.

PHAC_ASPC_OAUTH_USE_BACKEND = "custom.authentication.backend"
PHAC_ASPC_OAUTH_REDIRECT_ON_LOGIN = "home"

# pylint: disable=wrong-import-position, unused-wildcard-import, wildcard-import
from phac_aspc.django.settings import *

Note It is important that these settings be declared before the wildcard import.

Here is an example custom backend that sets the user's name to the value provided by the identity service.

from typing import Any

from django.contrib.auth import get_user_model
from django.contrib.auth.backends import BaseBackend
from django.contrib.auth.base_user import AbstractBaseUser
from django.http.request import HttpRequest


class OAuthBackend(BaseBackend):
    def _get(self, user_info, value, default=""):
        return user_info[value] if value in user_info else default

    def _should_update(self, user_info, value, current):
        v = self._get(user_info, value)
        return v != "" and v != current

    def _sync_user(self, user, user_info, force=False):
        if (
            force
            or self._should_update(user_info, "email", user.email)
            or self._should_update(user_info, "name", user.first_name)
        ):
            user.email = self._get(user_info, "email", user.email)
            user.first_name = self._get(user_info, "name", user.first_name)
            user.save()

    def authenticate(
        self,
        request: HttpRequest,
        user_info: dict | None = None,
        **kwargs: Any,
    ) -> AbstractBaseUser | None:
        if user_info is not None:
            user_model = get_user_model()
            try:
                user = user_model.objects.get(username=user_info["oid"])
                self._sync_user(user, user_info)
            except user_model.DoesNotExist:
                user = user_model(username=user_info["oid"])
                self._sync_user(user, user_info, True)
            return user
        return None

    def get_user(self, user_id):
        user_model = get_user_model()
        try:
            return user_model.objects.get(pk=user_id)
        except user_model.DoesNotExist:
            return None

Sign-in with Microsoft Environment Variables

Variable	Type	Purpose
PHAC_ASPC_OAUTH_PROVIDER	str	Only "microsoft" is supported at the moment.
PHAC_ASPC_OAUTH_APP_CLIENT_ID	str	Client ID (from the App Registration)
PHAC_ASPC_OAUTH_APP_CLIENT_SECRET	str	Client Secret (from the App Registration)
PHAC_ASPC_OAUTH_MICROSOFT_TENANT	str	Microsoft Tenant ID

Template Tag

A "Sign in with Microsoft" button is available as a template tag:

{% load phac_aspc_auth %}
{% phac_aspc_auth_signin_microsoft_button %}

To redirect to a specific page after logging in, pass the next query parameter through to the template tag as an argument.

e.g. with Jinja, on a login page where the URL ends with ?next=/some-protected-page/:

{{ phac_aspc.phac_aspc_auth_signin_microsoft_button(request.GET.urlencode()) }}

Handling Errors

If there are any errors during the authentication flow, they are displayed to the user via the error.html template. The template can be extended using standard django templating by creating a templates/phac_aspc/helpers/auth/error.html file in the host project.

Strings and locales

Strings displayed to the user during the authentication flow are available in Canada's both official languages. These strings can be customized by creating templates in the host project. Here is a list of strings and templates used by the authentication flow:

Template	Context
error_title.html	Error page title tag value
error_page_description.html	Description of error page (meta tag)
error_type_general.html	Error header displayed for general exceptions
error_type_oauth.html	Error header displayed for authentication errors
error_retry.html	Text of retry link
microsoft_logo.html	Alt text of sign the Microsoft logo in signin button
signin_with_microsoft.html	Text displayed in sign in button

Note String templates should be placed in the templates/phac_aspc/helpers/strings directory.

Security Controls

AC-7 Automatic lockout of users after invalid login attempts

django-axes is used to monitor and lockout users who fail to successfully authenticate.

The default configuration makes the following configuration changes to django:

• An attempt is identified by the combination of incoming IP address and the username,
• Both successful logins and failures are recorded to the database,
• The django project is assumed to be behind 1 reverse proxy (SSL),
• After 3 login failures, the account is locked out for 30 minutes.

To require an administrator to unlock the account, or to alter the lockout duration, you can modify the AXES_COOLOFF_TIME setting.

# settings.py

# Examples of AXES_COOLOFF_TIME settings
AXES_COOLOFF_TIME = None   # An administrator must unlock the account
AXES_COOLOFF_TIME = 2      # Accounts will be locked out for 2 hours

For more information regarding available configuration options, visit django-axes's documentation

There are also a few command line management commands available, for example to remove all of the lockouts you can run:

python -m manage axes_reset

See the usage documentation for more details.

AC-11 Session Timeouts

The default configuration makes the following configuration changes to django:

• Sessions timeout in 20 minutes,
• Sessions cookies are marked as secure,
• Sessions cookies are discarded when the browser is closed,
• Any requests to the server automatically extends the session.

You can override any of these settings by adding them below the settings import line. For example to use 30 minutes sessions:

#settings.py

from phac_aspc.django.settings import *

SESSION_COOKIE_AGE=1800

Configuration parameters can also be overridden using environment variables. For example here is a .env file that achieves the same result as above.

# .env
PHAC_ASPC_SESSION_COOKIE_AGE=1800

For more information on sessions, refer to Django's documentation

Additionally the Session Timeout UI control is available to warn users their session is about to expire, and provide mechanisms to automatically renew the session by clicking anywhere on the page, or by clicking on the "extend session" button when less than 3 minutes remain.

To use it, make sure your base template has WET setup as described above, and add the following line somewhere in your body tag.

{% phac_aspc_wet_session_timeout_dialog 'logout' %}

or if you're using Jinja

{{ phac_aspc.phac_aspc_wet_session_timeout_dialog(
    dict(request=request),
    'logout'
   )
}}

Make sure the above is included on every page where a user can be signed in, preferably in the base template for the entire site.

For more information on session timeout, visit the documentation.

Session Timeout Environment variables

All variables are prefixed with PHAC_ASPC_ to avoid name conflicts.

Variable	Type	Purpose
PHAC_ASPC_SESSION_COOKIE_AGE	int	Session expiry in seconds
PHAC_ASPC_SESSION_COOKIE_SECURE	bool	Use secure cookies (HTTPS only)

Localization

Django will be configured to support English (en-ca) and French (fr-ca). This can be changed in your projects settings using LANGUAGES and LANGUAGE_CODE.

For more information on Django's localization, see their documentation.

Localization Environment variables

Variable	Type	Purpose
PHAC_ASPC_LANGUAGE_CODE	str	Default language

lang template tag

In your templates, retrieve the current language code using the lang tag.

{% load localization %}
<html lang="{% lang %}">

Or in you're using Jinja

<html lang="{{ phac_aspc.localization.lang() }}">

translate decorator

Use this decorator on your models to add translations via django-modeltranslation. The example below adds translations for the title field.

from django.db import models
from phac_aspc.django.localization.decorators import translate

@translate('title')
class Person(models.Model):
    name = models.CharField(max_length=255)
    title = models.CharField(max_length=255)

add_admin decorator

Use this decorator on your model to quickly add it to Django's admin interface.

from django.db import models
from phac_aspc.django.admin.decorators import add_admin

@add_admin()
class Person(models.Model):
    ...

You can also specify inline models as well as additional ModelAdmin parameters via inlines and admin_options respectively.

class SignalLocation(models.Model):
    signal = models.ForeignKey("Signal", on_delete=models.CASCADE)
    location = models.String()

@add_admin(
  admin_options={'filter_horizontal': ('source',)},
  inlines=[SignalLocation]
)
class Signal(models.Model):
    title = models.CharField(max_length=400)
    location = models.ManyToManyField("Location", through='SignalLocation')

Jinja2 and Django Template Language (DTL) cross-language-includes

We provide a Jinja2 utility function and a DTL template tag which allows each to "include" from (render inline, using the including template's context) from one template language to the other.

include_from_dtl Jinja2 util

Add the util to your jinja environment:

import phac_aspc.django.helpers.jinja_utils as include_from_dtl


def environment(**options):
    env = Environment(**options)
    env.globals.update({
       ..., # other utils and constants
       "include_from_dtl": include_from_dtl,
    })
    return env

And then use it from a Jinja2 template:

{{ include_from_dtl("some/dtl/template/path.html") }}

phac_aspc_include_from_jinja DTL template tag

To register the phac_aspc_... template tags, add phac_aspc.django.helpers to INSTALLED_APPS in your settings.py.

You can then use the template tag in your DTL templates:

{% load phac_aspc_include_from_jinja %}
{% phac_aspc_include_from_jinja "some/Jinja2/template/path.jinja2" %}

Logging

Default logging configuration

A ready-to-use default logging configuration is available from phac_aspc.django.settings.logging, with an environment variable based API for limited project-specific configuration. To use, just import * from the module in to your settings.py and set PHAC_ASPC_LOGGING_USE_HELPERS_CONFIG=true in either your .env file or settings.py (before the phac_aspc imports).

#settings.py

from phac_aspc.django.settings.logging import *
# OR, along with all the other settings, via `from phac_aspc.django.settings import *`

For a local dev environment, I recommend setting PHAC_ASPC_LOGGING_PRETTY_FORMAT_CONSOLE_LOGS=True, to switch from JSON string formatted logs to friendlier console log formatting (coloured text, indentation, etc).

For a Google Cloud environment, the default configuration of writing JSON strings to stdout is prod-ready.

For an Azure Cloud environment, I recommend creating an Azure Monitor resource, getting your azure insights connection string for it, and configuring the app to log to it via the PHAC_ASPC_LOGGING_AZURE_INSIGHTS_CONNECTION_STRING env var. This will enable and use a pre-configured Azure log handler, outputing logs with JSON formatted message fields.

In any production environment, you can optionally provide a Slack webhook via PHAC_ASPC_LOGGING_SLACK_WEBHOOK_URL. This will send error and critical level logs to the webhook's slack channel. Note: this slack logging handler filters out django.security.DisallowedHost logs, as they are a constant background noise. Other handlers still capture them.

Default Logging Configuration environment variables

These env vars configure the default logging configuration provided by phac_aspc.django.settings.logging. If you don't both set PHAC_ASPC_LOGGING_USE_HELPERS_CONFIG=True and import those import those settings in your own settings.py, then the other env vars here won't do anything.

Variable	Type	Purpose
PHAC_ASPC_LOGGING_USE_HELPERS_CONFIG	bool	set to true to use the PHAC helper provided logging configuration
PHAC_ASPC_LOGGING_LOWEST_LEVEL	str	lowest logging level to print
PHAC_ASPC_LOGGING_MUTE_CONSOLE_HANDLER	bool	mutes the default console handler output
PHAC_ASPC_LOGGING_PRETTY_FORMAT_CONSOLE_LOGS	bool	pretty format console logs (coloured text)
PHAC_ASPC_LOGGING_AZURE_INSIGHTS_CONNECTION_STRING	str	if set, add a Azure log handler
PHAC_ASPC_LOGGING_SLACK_WEBHOOK_URL	str	if set, add a Slack Webhook handler

Note these env vars are consumed only within phac_aspc.django.settings.logging. If using configure_uniform_std_lib_and_structlog_logging directly, these env vars won't do anything.

add_fields_to_all_logs_for_current_request

When the server is processing a request, this function adds additional key-value fields to the logging context. Added context is will be present in subsequent logs*. Context is cleared between requests.

* at least, it will be in the structlog event_dict passed to the formatter (rendering processor). All of the default PHAC helper formatters will serialize the context in to the final log output. Custom formatters may not.

Requires use of the PHAC helper's logging configuration and the django_structlog RequestMiddleware. The PHAC helper's logging configuration ensures these context vars are rendered when logging, and the django_structlog RequestMiddleware handles clearing the structlog contextvars between requests.

Customized logging configuration via configure_uniform_std_lib_and_structlog_logging

Deeper customization can be achieved by forgoing a * import from phac_aspc.django.settings.logging, directly calling phac_aspc.django.helpers.logging.configure_logging.configure_uniform_std_lib_and_structlog_logging in your settings.py instead. Be aware that this bypasses the PHAC_ASPC_HELPER_LOGGING_... env vars, which are all only used in the phac_aspc.django.settings.logging module.

See the configure_uniform_std_lib_and_structlog_logging doc string for further details.

E.g. Muting the default console handler and using a custom file handler with a custom formatter

#settings.py

import structlog

from phac_aspc.django.helpers.logging.configure_logging import (
    configure_uniform_std_lib_and_structlog_logging,
    DEFAULT_STRUCTLOG_PRE_PROCESSORS,
)

LOGGING_CONFIG = None

configure_uniform_std_lib_and_structlog_logging(
    mute_console_handler=True,
    additional_handler_configs={
        "file": {
            "class": "logging.handlers.RotatingFileHandler",
            "level": "INFO",
            "filename": "logs",
            "mode": "a",
            "encoding": "utf-8",
            "maxBytes": 500000,
            "backupCount": 4
            "formatter": "custom_formatter",
        }
    },
    additional_formatter_functions={
        "custom_formatter": (
            lambda _logging, _name, structlog_event_dict: (
                f"{structlog_event_dict.timestamp}: {structlog_event_dict.event}"
            )
        )
    }
)

Contributing

Local development

You can consume the helpers project locally by installing it in editable mode. This is useful for extracting project features into this library. In your requirements.txt, comment out the line with django-phac_aspc-helpers, and add the following line with the file path to this repo, then re-install. Make sure to first uninstall the package if it was already installed, e.g. pip uninstall -y django-phac_aspc-helpers

-e file:///absolute_path/to/django-phac_aspc-helpers

Generating test coverage

1. coverage run --source=. ./manage.py test
2. coverage html
3. python -m http.server 1337
4. visit http://localhost:1337/htmlcov/ and dig into modules to see which individual line coverage