configurations.values
0.4
django-configurations allows you to optionally reduce the amount of validation and setup code in your settings.py by using Value
classes. They have the ability to handle values from the process environment of your software (os.environ
) and work well in projects that follow the Twelve-Factor methodology.
Note
These classes are required to be used as attributes of Configuration
classes. See the main documentation<index>
for more information.
Here is an example (from a settings.py file with a Configuration
subclass):
from configurations import Configuration, values
class Dev(Configuration):
DEBUG = values.BooleanValue(True)
As you can see all you have to do is to wrap your settings value in a call to one of the included values classes. When Django's process starts up it will automatically make sure the passed-in value validates correctly --in the above case checks if the value is really a boolean.
You can safely use other ~Value
instances as the default setting value:
from configurations import Configuration, values
class Dev(Configuration):
DEBUG = values.BooleanValue(True)
TEMPLATE_DEBUG = values.BooleanValue(DEBUG)
See the list of built-in value classes<built-ins>
for more information.
To separate the site configuration from your application code you should use environment variables for configuration. Unfortunately environment variables are string based so they are not easily mapped to the Python based settings system Django uses.
Luckily django-configurations' ~Value
subclasses have the ability to handle environment variables for the common use cases.
For example, imagine you want to override the ROOT_URLCONF
setting on your staging server to be able to debug a problem with your in-development code. You're using a web server that passes the environment variables from the shell it was started from into your Django WSGI process.
Use the boolean environ
option of the ~Value
class (True
by default) to tell django-configurations to look for an environment variable with the same name as the specific ~Value
variable, only uppercased and prefixed with DJANGO_
. E.g.:
from configurations import Configuration, values
class Stage(Configuration):
# ..
ROOT_URLCONF = values.Value('mysite.urls')
django-configurations will try to read the DJANGO_ROOT_URLCONF
environment variable when deciding which value the ROOT_URLCONF
setting should have. When you run the web server simply specify that environment variable (e.g. in your init script):
DJANGO_ROOT_URLCONF=mysite.debugging_urls gunicorn mysite.wsgi:application
If the environment variable can't be found it'll use the default 'mysite.urls'
.
To disable environment variables, specify the environ
parameter of the ~Value
class. For example this would disable it for the TIME_ZONE
setting value:
from configurations import Configuration, values
class Dev(Configuration):
TIME_ZONE = values.Value('UTC', environ=False)
To support legacy systems, integrate with other parts of your software stack or simply better match your taste in naming public configuration variables, django-configurations allows you to use the environ_name
parameter of the ~Value
class to change the base name of the environment variable it looks for. For example this would enforce the name DJANGO_MYSITE_TZ
instead of using the name of the ~Value
instance.:
from configurations import Configuration, values
class Dev(Configuration):
TIME_ZONE = values.Value('UTC', environ_name='MYSITE_TZ')
You may use the environ_name
parameter to allow a ~Value
to be directly converted to its final value for use outside of the configuration context:
>>> type(values.Value([]))
<class 'configurations.values.Value'>
>>> type(values.Value([], environ_name="FOOBAR"))
<class 'list'>
This can also be achieved when using environ=False
and providing a default value.
In case you want to change the default environment variable name prefix of DJANGO
to something to your likening, use the environ_prefix
parameter of the ~Value
instance. Here it'll look for the MYSITE_TIME_ZONE
environment variable (instead of DJANGO_TIME_ZONE
):
from configurations import Configuration, values
class Dev(Configuration):
TIME_ZONE = values.Value('UTC', environ_prefix='MYSITE')
The environ_prefix
parameter can also be None
to completely disable the prefix.
The Value
class takes one required and several optional parameters.
- param default
the default value of the setting
- param environ
toggle for environment use
- param environ_name
name of environment variable to look for
- param environ_prefix
prefix to use when looking for environment variable
- param environ_required
wheter or not the value is required to be set as an environment variable
- type environ
bool
- type environ_name
capitalized string or None
- type environ_prefix
capitalized string
- type environ_required
bool
The default
parameter is effectively the value the setting has right now in your settings.py
.
setup(name)
- param name
the name of the setting
- return
setting value
The setup
method is called during startup of the Django process and implements the ability to check the environment variable. Its purpose is to return a value django-configurations is supposed to use when loading the settings. It'll be passed one parameter, the name of the ~Value
instance as defined in the settings.py
. This is used for building the name of the environment variable.
to_python(value)
- param value
the value of the setting as found in the process environment (
os.environ
)- return
validated and "ready" setting value if found in process environment
The to_python
method is used when the environ
parameter of the ~Value
class is set to True
(the default) and an environment variable with the appropriate name was found.
It will be used to handle the string based environment variables and returns the "ready" value of the setting.
Some ~Value
subclasses also use it during initialization when the default value has a string-like format like an environment variable which needs to be converted into a Python data type.
A ~Value
subclass that checks and returns boolean values. Possible values for environment variables are:
True
values:'yes'
,'y'
,'true'
,'1'
False
values:'no'
,'n'
,'false'
,'0'
,''
(empty string)
DEBUG = values.BooleanValue(True)
A ~Value
subclass that handles integer values.
MYSITE_CACHE_TIMEOUT = values.IntegerValue(3600)
A ~Value
subclass that handles positive integer values.
2.1
MYSITE_WORKER_POOL = values.PositiveIntegerValue(8)
A ~Value
subclass that handles float values.
MYSITE_TAX_RATE = values.FloatValue(11.9)
A ~Value
subclass that handles Decimal values.
MYSITE_CONVERSION_RATE = values.DecimalValue(decimal.Decimal('4.56214'))
A ~SequenceValue
subclass that handles list values.
- param separator
the separator to split environment variables with
- param converter
the optional converter callable to apply for each list item
Simple example:
ALLOWED_HOSTS = ListValue(['mysite.com', 'mysite.biz'])
Use a custom converter to check for the given variables:
def check_monty_python(person):
if not is_completely_different(person):
error = '{0} is not a Monty Python member'.format(person)
raise ValueError(error)
return person
MONTY_PYTHONS = ListValue(['John Cleese', 'Eric Idle'],
converter=check_monty_python)
You can override this list with an environment variable like this:
DJANGO_MONTY_PYTHONS="Terry Jones,Graham Chapman" gunicorn mysite.wsgi:application
Use a custom separator:
EMERGENCY_EMAILS = ListValue(['admin@mysite.net'], separator=';')
And override it:
DJANGO_EMERGENCY_EMAILS="admin@mysite.net;manager@mysite.org;support@mysite.com" gunicorn mysite.wsgi:application
A ~SequenceValue
subclass that handles tuple values.
- param separator
the separator to split environment variables with
- param converter
the optional converter callable to apply for each tuple item
See the ~ListValue
examples above.
A ~SingleNestedSequenceValue
subclass that handles single nested tuple values, e.g. ((a, b), (c, d))
.
- param seq_separator
the separator to split each tuple with
- param separator
the separator to split the inner tuple contents with
- param converter
the optional converter callable to apply for each inner tuple item
Useful for ADMINS, MANAGERS, and the like. For example:
ADMINS = SingleNestedTupleValue((
('John', 'jcleese@site.com'),
('Eric', 'eidle@site.com'),
))
Override using environment variables like this:
DJANGO_ADMINS=Terry,tjones@site.com;Graham,gchapman@site.com
A ~SingleNestedSequenceValue
subclass that handles single nested list values, e.g. [[a, b], [c, d]]
.
- param seq_separator
the separator to split each list with
- param separator
the separator to split the inner list contents with
- param converter
the optional converter callable to apply for each inner list item
See the ~SingleNestedTupleValue
examples above.
A ~Value
subclass that handles set values.
- param separator
the separator to split environment variables with
- param converter
the optional converter callable to apply for each set item
See the ~ListValue
examples above.
A ~Value
subclass that handles dicts.
DEPARTMENTS = values.DictValue({ 'it': ['Mike', 'Joe'], })
A ~Value
subclass that validates the value using the django:django.core.validators.validate_email
validator.
SUPPORT_EMAIL = values.EmailValue('support@mysite.com')
A ~Value
subclass that validates the value using the django:django.core.validators.URLValidator
validator.
SUPPORT_URL = values.URLValue('https://support.mysite.com/')
A ~Value
subclass that validates the value using the django:django.core.validators.validate_ipv46_address
validator.
LOADBALANCER_IP = values.IPValue('127.0.0.1')
A ~Value
subclass that validates according a regular expression and uses the django:django.core.validators.RegexValidator
.
- param regex
the regular expression
DEFAULT_SKU = values.RegexValue('000-000-00', regex=r'\d{3}-\d{3}-\d{2}')
A ~Value
subclass that normalizes the given path using os.path.expanduser
and checks if it exists on the file system.
Takes an optional check_exists
parameter to disable the check with os.path.exists
.
- param check_exists
toggle the file system check
BASE_DIR = values.PathValue('/opt/mysite/')
STATIC_ROOT = values.PathValue('/var/www/static', checks_exists=False)
Note
The following URL-based ~Value
subclasses are inspired by the Twelve-Factor methodology and use environment variable names that are already established by that methodology, e.g. 'DATABASE_URL'
.
Each of these classes require external libraries to be installed, e.g. the ~DatabaseURLValue
class depends on the package dj-database-url
. See the specific class documentation below for which package is needed.
A ~Value
subclass that uses the dj-database-url app to convert a database configuration value stored in the DATABASE_URL
environment variable into an appropriate setting value. It's inspired by the Twelve-Factor methodology.
By default this ~Value
subclass looks for the DATABASE_URL
environment variable.
Takes an optional alias
parameter to define which database alias to use for the DATABASES
setting.
- param alias
which database alias to use
The other parameters have the following default values:
- param environ
True
- param environ_name
DATABASE_URL
- param environ_prefix
None
DATABASES = values.DatabaseURLValue('postgres://myuser@localhost/mydb')
A ~Value
subclass that uses the django-cache-url app to convert a cache configuration value stored in the CACHE_URL
environment variable into an appropriate setting value. It's inspired by the Twelve-Factor methodology.
By default this ~Value
subclass looks for the CACHE_URL
environment variable.
Takes an optional alias
parameter to define which database alias to use for the CACHES
setting.
- param alias
which cache alias to use
The other parameters have the following default values:
- param environ
True
- param environ_name
CACHE_URL
- param environ_prefix
None
CACHES = values.CacheURLValue('memcached://127.0.0.1:11211/')
A ~Value
subclass that uses the dj-email-url app to convert an email configuration value stored in the EMAIL_URL
environment variable into the appropriate settings. It's inspired by the Twelve-Factor methodology.
By default this ~Value
subclass looks for the EMAIL_URL
environment variable.
Note
This is a special value since email settings are divided into many different settings variables. dj-email-url supports all options though and simply returns a nested dictionary of settings instead of just one setting.
The parameters have the following default values:
- param environ
True
- param environ_name
EMAIL_URL
- param environ_prefix
None
EMAIL = values.EmailURLValue('console://')
0.8
A ~Value
subclass that uses the dj-search-url app to convert a search configuration value stored in the SEARCH_URL
environment variable into the appropriate settings for use with Haystack. It's inspired by the Twelve-Factor methodology.
By default this ~Value
subclass looks for the SEARCH_URL
environment variable.
Takes an optional alias
parameter to define which search backend alias to use for the HAYSTACK_CONNECTIONS
setting.
- param alias
which cache alias to use
The other parameters have the following default values:
- param environ
True
- param environ_name
SEARCH_URL
- param environ_prefix
None
HAYSTACK_CONNECTIONS = values.SearchURLValue('elasticsearch://127.0.0.1:9200/my-index')
A ~ListValue
subclass that validates the given list of dotted import paths by trying to import them. In other words, this checks if the backends exist.
MIDDLEWARE_CLASSES = values.BackendsValue([
'django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
])
A ~Value
subclass that doesn't allow setting a default value during instantiation and force-enables the use of an environment variable to reduce the risk of accidentally storing secret values in the settings file.
- raises
ValueError
when given a default value
1.0
This value class has the environ_required
parameter turned to True
.
SECRET_KEY = values.SecretValue()
A mixin to be used with one of the ~Value
subclasses that requires a caster
class attribute of one of the following types:
- dotted import path, e.g.
'mysite.utils.custom_caster'
- a callable, e.g.
int
Example:
class TemparatureValue(CastingMixin, Value):
caster = 'mysite.temperature.fahrenheit_to_celcius'
Optionally it can take a message
class attribute as the error message to be shown if the casting fails. Additionally an exception
parameter can be set to a single or a tuple of exception classes that are required to be handled during the casting.
A mixin to be used with one of the ~Value
subclasses that requires a validator
class attribute of one of the following types: The validator should raise Django's ~django.core.exceptions.ValidationError
to indicate a failed validation attempt.
- dotted import path, e.g.
'mysite.validators.custom_validator'
- a callable, e.g.
bool
Example:
class TemparatureValue(ValidationMixin, Value):
validator = 'mysite.temperature.is_valid_temparature'
Optionally it can take a message
class attribute as the error message to be shown if the validation fails.
A mixin to be used with one of the ~Value
subclasses that enables the return value of the ~Value.to_python
to be interpreted as a dictionary of settings values to be set at once, instead of using the return value to just set one setting.
A good example for this mixin is the ~EmailURLValue
value which requires setting many EMAIL_*
settings.