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PHP Server SDK

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.

To successfully use the PHP SDK, you need to

  1. Install it
  2. Provide a storage adapter to cache config and event logs (easy default exists)
  3. Schedule a Cron job to poll for config changes and flush event logs to Statsig
  4. Initialize and use the SDK

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 expose it, you can create a new one in the 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.

You should create an adapter that implements Statsig\Adapters\IConfigAdapter that hooks up to your caching solution. By default, we provide a local file solution that can be useful for first time setup but is challenging to work with in production settings.

For help with the interface and implementing an adapter, browse the adapters directory in the open source SDK repository.

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 job 🔥​

caution

V3.0+​

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

See Cron Jobs

Working with the SDK​

Checking a Feature Flag/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)

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();

Learn more about identifying users, group analytics, and best practices for logging events in the logging events guide.

Retrieving Feature Gate Metadata​

In certain scenarios, you may need more information about a gate evaluation than just a boolean value. For additional metadata about the evaluation, use the Get Feature Gate API, which returns a FeatureGate object

Manual Exposures v3.4.0+​

warning

Manually logging exposures can be tricky and may lead to an imbalance in exposure events. For example, only triggering exposures for users in the Test group of an experiment will imbalance the experiment, making it useless.

Added in version 3.4.0, you can now query your gates/experiments without triggering an exposure as well as manually logging your exposures.

To check a gate without an exposure being logged, call the following.

$result = $this->statsig->checkGateWithExposureLoggingDisabled($user, 'a_gate_name');

Later, if you would like to expose this gate, you can call the following.

$this->statsig->manuallyLogGateExposure($user, 'a_gate_name');

Cron Jobs​

To keep your configurations up to date, and send event data to Statsig, you can create two jobs. Here, we document them as cron jobs, but you can use any out of band process to run them. If you are using Laravel, for example, you can use Commands to run them locally and on a schedule.

Sync​

The first job 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

You should provide your own custom adapter that implements Statsig\Adapters\IDataAdapter

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 LocalFileDataAdapter 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

You should provide your own custom adapter that implements Statsig\Adapters\ILoggingAdapter

php send.php --secret <STATSIG_SECRET_KEY> \
     --adapter-class Namespace\For\MyLoggingAdapter \
     --adapter-path /path/to/MyLoggingAdapter.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.

Note that while typing is lenient on the StatsigUser object to allow you to pass in numbers, strings, arrays, objects, and potentially even enums or classes, the evaluation operators will only be able to operate on primitive types - mostly strings and numbers. While we attempt to smartly cast custom field types to match the operator, we cannot guarantee evaluation results for other types. For example, setting an array as a custom field will only ever be compared as a string - there is no operator to match a value in that array.

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" | <string>)
  • The event queue size (How many events to track before they are sent to Statsig) via setEventQueueSize(int $size).

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(IDataAdapter $data_adapter, ?ILoggingAdapter $logging_adapter = null, ?IOutputLogger $output_logger = null)

    function getConfigAdapter(): IConfigAdapter

    function getLoggingAdapter(): ?ILoggingAdapter

    /**
     * Configure an output logger for additional debugging information
     */
    function getOutputLogger(): ?IOutputLogger

    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;
}