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Python Server SDK

Getting Started​

The following will outline how to get up and running with Statsig for Python.

Create an Account​

To work with the SDK, you will need a Statsig account. If you don't yet have an account, you can sign up for a free one here. You could skip this for now, but you will need an SDK key and some gates/experiments to use with the SDK in just a minute.

Installation​

Install the sdk using pip3:

NOTE: The Statsig SDK is not compatibile with python 2. You must be on python 3 to use the Statsig SDK.

pip3 install statsig

Initialize the SDK​

After installation, you will need to initialize the SDK using a Server Secret Key from the statsig console.

info

Do NOT embed your Server Secret Key in client side applications, or expose it in any external facing documents. However, if you accidentally exposed it, you can create a new one in Statsig console.

There is also an optional parameter named options that allows you to pass in a StatsigOptions to customize the SDK.
from statsig import statsig

statsig.initialize("server-secret-key")

# or with StatsigOptions
options = StatsigOptions(tier=StatsigEnvironmentTier.development)
statsig.initialize("server-secret-key", options)
initialize will perform a network request. After initialize completes, virtually all SDK operations will be synchronous (See Evaluating Feature Gates in the Statsig SDK). The SDK will fetch updates from Statsig in the background, independently of your API calls.

Working with the SDK​

Checking a Gate​

Now that your SDK is initialized, let's fetch a Feature Gate. Feature Gates can be used to create logic branches in code that can be rolled out to different users from the Statsig Console. Gates are always CLOSED or OFF (think return false;) by default.

From this point on, all APIs will require you to specify the user (see Statsig user) associated with the request. For example, check a gate for a certain user like this:

from statsig.statsig_user import StatsigUser

...

statsig.check_gate(StatsigUser("user-id"), "gate-name")

Reading a Dynamic Config​

Feature Gates can be very useful for simple on/off switches, with optional but advanced user targeting. However, if you want to be able send a different set of values (strings, numbers, and etc.) to your clients based on specific user attributes, e.g. country, Dynamic Configs can help you with that. The API is very similar to Feature Gates, but you get an entire json object you can configure on the server and you can fetch typed parameters from it. For example:

config = statsig.get_config(StatsigUser("user-id"), "config-name")

config_json = config.get_value()

Getting an Layer/Experiment​

Then we have Layers/Experiments, which you can use to run A/B/n experiments. We offer two APIs, but we recommend the use of layers to enable quicker iterations with parameter reuse.

# Values via getLayer

layer = statsig.get_layer(user, "user_promo_experiments")
title = layer.get("title", "Welcome to Statsig!")
discount = layer.get("discount", 0.1)

# or, via getExperiment

title_exp = statsig.get_experiment(user, "new_user_promo_title")
price_exp = statsig.get_experiment(user, "new_user_promo_price")

title = title_exp.get("title", "Welcome to Statsig!")
discount = price_exp.get("discount", 0.1)

...

price = msrp * (1 - discount)

Asynchronous APIs

We mentioned earlier that after calling initialize most SDK APIs would run synchronously, so why are getConfig and checkGate asynchronous?

The main reason is that older versions of the SDK might not know how to interpret new types of gate conditions. In such cases the SDK will make an asynchronous call to our servers to fetch the result of a check. This can be resolved by upgrading the SDK, and we will warn you if this happens.

For more details, read our blog post about SDK evaluations. If you have any questions, please ask them in our Feedback Repository.

Logging an Event​

Now that you have a Feature Gate or an Experiment set up, you may want to track some custom events and see how your new features or different experiment groups affect these events. This is super easy with Statsig - simply call the Log Event API and specify the user and event name to log; you additionally provide some value and/or an object of metadata to be logged together with the event:

from statsig.statsig_user import StatsigUser
from statsig.statsig_event import StatsigEvent

statsig.log_event(StatsigEvent(StatsigUser("user-id"), "event-name"))

Statsig User​

When calling APIs that require a user, you should pass as much information as possible in order to take advantage of advanced gate and config conditions (like country or OS/browser level checks), and correctly measure impact of your experiments on your metrics/events. The userID field is required because it's needed to provide a consistent experience for a given user (click here to understand further why it's important to always provide a userID).

Besides userID, we also have email, ip, userAgent, country, locale and appVersion as top-level fields on StatsigUser. In addition, you can pass any key-value pairs in an object/dictionary to the custom field and be able to create targeting based on them.

user = StatsigUser(
    user_id="123",
    email="testuser@statsig.com",
    ip="192.168.1.101",
    user_agent="Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.78 Safari/537.36",
    country="US",
    locale="en_US",
    app_version="4.3.0",
    custom={"cohort": "June 2021"},
    private_attributes={"gender": "female"},
)

Private Attributes​

Have sensitive user PII data that should not be logged? No problem, we have a solution for it! On the StatsigUser object we also have a field called privateAttributes, which is a simple object/dictionary that you can use to set private user attributes. Any attribute set in privateAttributes will only be used for evaluation/targeting, and removed from any logs before they are sent to Statsig server.

For example, if you have feature gates that should only pass for users with emails ending in "@statsig.com", but do not want to log your users' email addresses to Statsig, you can simply add the key-value pair { email: "my_user@statsig.com" } to privateAttributes on the user and that's it!

Statsig Options​

statsig.initialize() takes an optional parameter options in addition to the secret key that you can provide to customize the Statsig client. Create a StatsigOptions class to pass in with the following available parameters:

  • tier: StatsigEnvironmentTier | str, default None

    • Sets the environment tier (for gates to evaluate differently in development and production)
    • You can set an environment tier with the StatsigEnvironmentTier enum or just as a str

  • timeout: timeout: int = None

    • Enforces a minimum timeout on network requests from the SDK

  • rulesets_sync_interval: rulesets_sync_interval: int = 10

    • How often the SDK updates rulesets from Statsig servers

  • idlists_sync_interval: idlists_sync_interval: int = 60

    • How often the SDK updates idlists from Statsig servers

  • local_mode: local_mode: bool=False

    • Disables all network requests. SDK returns default values and will not log events. Useful in combination with overrides to mock behavior for tests

  • bootstrap_values: bootstrap_values: str = null

    • a string that represents all rules for all feature gates, dynamic configs and experiments. It can be provided to bootstrap the Statsig server SDK at initialization in case your server runs into network issue or Statsig server is down temporarily.

  • rules_updated_callback: rules_updated_callback: typing.Callable = None,

    • a callback function that's called whenever we have an update for the rules; it's called with a logical timestamp and a JSON string (used as is for bootstrapValues mentioned above). Note that as of v0.6.0, this will be called from a background thread that the SDK uses to update config values.

  • event_queue_size: event_queue_size: int = 500

    • The number of events to batch before flushing the queue to the network. Default 500.
    • Note that events are also batched every minute by a background thread

  • data_store: data_store: IDataStore = None

    • A data store with custom storage behavior for config specs. Can be used to bootstrap Statsig server (takes priority over bootstrap_values).

Example:

from statsig import statsig, StatsigEnvironmentTier, StatsigOptions

options = StatsigOptions(None, StatsigEnvironmentTier.development)
statsig.initialize("secret-key", options)

You can also use the set_environment_parameter function, but that takes in string values only:

from statsig import statsig, StatsigEnvironmentTier, StatsigOptions

options = StatsigOptions()
options.set_evironment_parameter("tier", StatsigEnvironmentTier.development.value)
statsig.initialize("secret-key", options)

Shutting Statsig Down​

Because we batch and periodically flush events, some events may not have been sent when your app/server shuts down.

To make sure all logged events are properly flushed, you should tell Statsig to shutdown when your app/server is closing:

statsig.shutdown()

Client SDK Bootstrapping | SSR v0.12.0+​

The Python server SDK, starting in 0.12.0 supports generating the initializeValues needed to bootstrap a Statsig Client SDK preventing a round trip to Statsig servers. This can also be used with web [statsig-js, statsig-react] SDKs to perform server side rendering (SSR).
values = statsig.get_client_initialize_response(user); # dict() | None

Working with IP or UserAgent Values​

This will not automatically use the ip, or userAgent for gate evaluation as Statsig servers would, since there is no request from the client SDK specifying these values. If you want to use conditions like IP, or conditions which are inferred from the IP/UA like: Browser Name or Version, OS Name or Version, Country, you must manually set the ip and userAgent field on the user object when calling get_client_initialize_response.

Working with StableID​

There is no auto-generated stableID for device based experimentation, since the server generates the initialize response without any information from the client SDK. If you wish to run a device based experiment while using the server to generate the initialize response, we recommend you:

  1. Create a customID in the Statsig console. See experimenting on custom IDs for more information.
  2. Generate an ID on the server, and set it in a cookie to be used on the client side as well.
  3. Set that ID as the customID on the StatsigUser object when generating the initialize response from the SDK.
  4. Get that ID from the cookie, and set it as the customID on the StatsigUser object when using the client SDK, so all event data and exposure checks tie back to the same user.

Alternatively, if you wish to use the stableID field rather than a custom ID, you still need to do step (2) above. Then:

  • Override the stableID in the client SDK by getting the value from the cookie and setting the overrideStableID parameter in StatsigOptions
  • Set the stableID field on the StatsigUser object in the customIDs map when generating the initialize response from the SDK

Local Overrides ​

If you want to locally override gates/configs/experiments/layers, there are a set of override APIs as follows. Coupling this with StatsigOptions.localMode can be useful when writing unit tests.

# Adding/Removing gate overrides
statsig.override_gate("a_gate_name", true, "a_user_id")
statsig.remove_gate_override("a_gate_name", "a_user_id")

# Adding/Removing config overrides
statsig.override_config("a_config_name", {"key": "value"}, "a_user_id")
statsig.remove_config_override("a_config_name", "a_user_id")

# Adding/Removing experiment overrides
statsig.override_experiment("an_experiment_name", {"key": "value"}, "a_user_id")
statsig.remove_experiment_override("an_experiment_name", "a_user_id")

# Remove All Overrides
statsig.remove_all_overrides()
note
  1. These only apply locally - they do not update definitions in the Statsig console or elsewhere.
  2. The local override API is not designed to be a full mock. They are only a convenient way to override the value of the gate/config/etc.

FAQ​

How do I run experiments for logged out users?​

See the guide on device level experiments

How can I mock Statsig for testing?​

The python server SDK, starting in version 0.5.1+, supports a few features to make testing easier.

First, there is a StatsigOption parameter called localMode. Setting localMode to true will cause the SDK to never hit the network, and only return default values. This is perfect for dummy environments or test environments that should not access the network.

Next, there are the overrideGate and overrideConfig APIs on the global statsig interface, see Local Overrides

These can be used to set a gate or config override for a specific user, or for all users (by not providing a specific user ID).

We suggest you enable localMode and then override gates/configs/experiments to specific values to test the various code flows you are building.

Can I generate the initialize response for a client SDK using the Python server SDK?​

Yes. See Client Initialize Response.

Reference​

StatsigUser​

@dataclass
class StatsigUser:
    """An object of properties relating to the current user
    user_id or at least a custom ID is required: learn more https://docs.statsig.com/messages/serverRequiredUserID
    Provide as many as possible to take advantage of advanced conditions in the statsig console
    A dictionary of additional fields can be provided under the custom field
    Set private_attributes for any user property you need for gate evaluation but prefer stripped from logs/metrics
    """
    user_id: Optional[str] = None
    email: Optional[str] = None
    ip: Optional[str] = None
    user_agent: Optional[str] = None
    country: Optional[str] = None
    locale: Optional[str] = None
    app_version: Optional[str] = None 
    custom: Optional[dict] = None # key: string, value: string
    private_attributes: Optional[dict] = None # key: string, value: string
    custom_ids: Optional[dict] = None # key: string, value: string

StatsigOptions​

class StatsigOptions:
    """An object of properties for initializing the sdk with additional parameters"""

    def __init__(
        self,
        api: str = "https://statsigapi.net/v1/",
        tier: Union[str, StatsigEnvironmentTier, None] = None,
        init_timeout: Optional[int] = None,
        timeout: Optional[int] = None,
        rulesets_sync_interval: int = 10,
        idlists_sync_interval: int = 60,
        local_mode: bool = False,
        bootstrap_values: Optional[str] = None,
        rules_updated_callback: Optional[Callable] = None,
        event_queue_size: Optional[int] = 500,
        data_store: Optional[IDataStore] = None,
        idlists_thread_limit: int = 3,
        logging_interval: int = 60
    ):

DataStore​

class IDataStore:
    def get(self, key: str) -> Optional[str]:
        return None

    def set(self, key: str, value: str):
        pass

    def shutdown(self):
        pass