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PHP Server SDK

Getting Started​

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

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​

You can install the PHP SDK using composer.

composer require statsig/statsigsdk

The SDK is also open source and hosted on github. The package is published to packagist.

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 a parameter options that requires you to pass in a storage adapter for storing configurations and event logs. In this below example, we use a local file storage adapter, but you can write your own to plug in Redis or another storage solution. Create an adapter that implements Statsig\Adapters\IConfigAdapter if you do not want to use the local file storage adapter.

caution

v3.0+​

You must setup ConfigAdapter and ensure configs are ready before initialize SDK. SDK does not make any network request call to download configs (and IDLists) anymore. Configs fetching should be handled by chron jobs and pre-initialization

require_once __DIR__ . '/vendor/autoload.php'; // path to installation folder

use Statsig\StatsigServer;
use Statsig\StatsigOptions;
use Statsig\Adapters\LocalFileDataAdapter;
use Statsig\Adapters\LocalFileLoggingAdapter;

$config_adapter = new LocalFileDataAdapter();
$logging_adapter = new LocalFileLoggingAdapter();
$options = new StatsigOptions($config_adapter, $logging_adapter);
$this->statsig = new StatsigServer("server-sdk-key", $options);

🔥 Warning - You need to schedule a cron job 🔥​

caution

V3.0+​

If you do not configure a cron job, SDK does not fire a network request to fetch the latest config value anymore, instead, config values fetched earlier will be used.

< V3.0​

If you do not configure a cron job, your request performance may be impacted. A check for configuration freshness is made before evaluation (checkGate/getConfig/getExperiment). If your configurations are over 1 minute old, a network request will be fired to Statsig to update them.

See Cron Jobs

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:

use Statsig\StatsigUser;

$user = StatsigUser::withUserID("123");
$user->setEmail("testuser@statsig.com");

$this->statsig->checkGate($user, "<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:

$this->statsig->getConfig($user, "<config_name>");

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 = $this->statsig->getLayer($user, "user_promo_experiments");
$title = $layer->get("title", "Welcome to Statsig!");
$discount = $layer->get("discount", 0.1);

// or, via getExperiment

$title_experiment = $this->statsig->getExperiment($user, "new_user_promo_title");
$price_experiment = $this->statsig->getExperiment($user, "new_user_promo_price");
$title = $title_experiment->get("title", "Welcome to Statsig!")
$discount = $price_experiment->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:

$event = new StatsigEvent("purchase");
$event->setUser($user);
$event->setValue("subscription");
$event->setMetadata(array("promotion" => "2022 deals"));
$this->statsig->logEvent($event);

At the end of the request, you can flush events to the log file using:

$this->statsig->flush();

Retrieving Feature Gate Metadata​

In certain scenarios, it's beneficial to access detailed information about a feature gate, such as its current state for a specific user or additional contextual data. This can be accomplished effortlessly through the Get Feature Gate API. By providing the necessary user details and the name of the feature gate you're interested in, you can fetch this metadata to inform your application's behavior or for analytical purposes.

Cron Jobs​

To keep your configurations up to date, and send event data to Statsig, you can create two cron jobs.

Sync​

The first runs sync.php to download the latest definition of gates/configs/experiments from Statsig, and save it to a config file locally. If you do not update this file, your gate/config/experiment values may be stale and will be refetched during a request, which may lead to slower response times.

# Run once
php sync.php --secret <STATSIG_SECRET_KEY>
# Create a cron job that runs as statsigsync every minute
echo '*/1 * * * * statsigsync php /my/path/to/statsig/sync.php --secret <STATSIG_SECRET_KEY> > /dev/null' | sudo tee /etc/cron.d/statsigsync
sudo service cron reload    # reload the cron daemon

Alternatively, you may provide your own custom adapter that implements Statsig\Adapters\IConfigAdapter if you do not want to use the local file storage adapter.

php send.php --secret <STATSIG_SECRET_KEY> \
    --adapter-class Namespace\For\MyConfigAdapter \
    --adapter-path /path/to/MyConfigAdapter.php \
    --adapter-arg an_argument_for_my_adapter \
    --adapter-arg another_argument

By default, sync.php will use the Statsig LocalFileLoggingAdapter which writes to /tmp/statsig.configs

Send​

The second runs send.php to send the exposure data and log events to statsig. Without this data, your events will need to be logged during the lifetime of the request, which may lead to slower response times.

# Run once
php send.php --secret <STATSIG_SECRET_KEY>
# Create a cron job that runs as statsigdata every minute
echo '*/1 * * * * statsigdata php /my/path/to/statsig/send.php --secret <STATSIG_SECRET_KEY> > /dev/null' | sudo tee /etc/cron.d/statsigdata
sudo service cron reload    # reload the cron daemon

Alternatively, you may provide your own custom adapter that implements Statsig\Adapters\ILoggingConfig if you do not want to use the local file storage adapter.

php send.php --secret <STATSIG_SECRET_KEY> \
     --adapter-class Namespace\For\MyConfigAdapter \
     --adapter-path /path/to/MyConfigAdapter.php \
     --adapter-arg an_argument_for_my_adapter \
     --adapter-arg another_argument

By default, send.php will use the Statsig LocalFileDataAdapter which writes to /tmp/statsig.logs

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.

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​

StatsigOptions is a common configuration parameter across Statsig SDKs. For the PHP SDK, the following are configurable:

  • IDataAdapter (required) - A class that implements IDataAdapter. Statsig provides the LocalFileDataAdapter, but you can write your own. See Data Stores.
  • ILoggingAdapter - A class that implements ILoggingAdapter. Statsig provides the LocalFileLoggingAdapter, but you can write your own. If no adapter is provided, logs will be sent during the request.

You can also configure:

  • The environment (see using environments) via setEnvironmentTier("production" | "staging" | "development")
  • The event queue size (How many events to track before they are sent to Statsig) via setEventQueueSize(int $size).
  • The freshness (how old in milliseconds) config definitions are allowed to be before a network request is issued to refetch them. Default 1 minute. Public config_freshness_threshold_ms member on StatsigOptions

Shutting Statsig Down​

Because we batch and periodically flush events, some events may still be in memory when your app/server shuts down.

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

$this->statsig->flush();

FAQ​

How do I run experiments for logged out users?​

See the guide on device level experiments

Can I use ID Lists with the PHP SDK?​

Yes, since version 2.0.0, ID Lists are now supported by the PHP SDK. Any SDK version less than v2.0.0 will not work with ID Lists.

Do I need the SDK, can I just use the HTTP API?​

If you want a simple snippet for using the http api in php, you may find the following gist useful. It exposes functions to checkGate, getConfig, getExperiment, and logEvent.

Note that the user parameter to each of these functions follows the Statsig User definition for Server SDKs.

Reference​

Class: StatsigUser​

class StatsigUser
{
    static function withUserID(string $user_id): StatsigUser

    static function withCustomIDs(array $custom_ids): StatsigUser

    function setUserID(?string $user_id): StatsigUser

    function setEmail(?string $email): StatsigUser

    function setIP(?string $ip): StatsigUser

    function setUserAgent(?string $user_agent): StatsigUser

    function setLocale(?string $locale): StatsigUser

    function setCountry(?string $country): StatsigUser

    function setAppVersion(?string $app_version): StatsigUser

    function setCustom(?array $custom): StatsigUser

    function setPrivateAttributes(?array $private): StatsigUser

    function setCustomIDs(?array $custom_ids): StatsigUser
}

Class: StatsigOptions​

class StatsigOptions
{
    function __construct(IConfigAdapter $config_adapter, ?ILoggingAdapter $logging_adapter = null)

    function getConfigAdapter(): IConfigAdapter

    function getLoggingAdapter(): ?ILoggingAdapter

    function setEnvironmentTier(?string $tier)
    /**
     * @throws Exception - Given size cannot be less than 10 or greater than 1000
     */
    function setEventQueueSize(int $size)
}

Interface: IDataAdapter​

interface IDataAdapter
{
    function get(string $key): ?string;
    function set(string $key, ?string $value);
}

Interface: ILoggingAdapter​

interface ILoggingAdapter
{
    public function enqueueEvents(array $events);
    public function getQueuedEvents(): array;
}