PHP SDK - Custom Logging

The PHP SDK reports what it is doing through the PSR-3 LoggerInterface. Pass any PSR-3 implementation as NexusConfig::$logger - Monolog, Laravel’s Log facade, Symfony’s autowired LoggerInterface. With $logger left null (the default), the SDK is silent.

Configuration

use WestyxNexus\NexusClient;
use WestyxNexus\NexusConfig;

$client = NexusClient::create(new NexusConfig(
    baseUrl: $_ENV['NEXUS_URL'],
    apiKey:  $_ENV['NEXUS_API_KEY'],
    logger:  $myPsr3Logger,
));

What the SDK logs

Level	Message	When emitted
`debug`	`nexus: sync completed`	After every successful sync
`debug`	`nexus: sync not modified`	The server returned `304`
`debug`	`nexus: SSE event received`	A recognised stream event arrived
`debug`	`nexus: SSE stream ended`	The stream closed and will be reconnected
`info`	`nexus: client ready`	After `NexusClient::create` returns
`info`	`nexus: WIF session established`	After a successful token exchange
`info`	`nexus: SSE reconnecting`	Before each reconnect attempt
`error`	`nexus: refresh failed, serving the cached snapshot`	A TTL-triggered sync failed transiently
`error`	`nexus: SSE transport error`	A stream connection failed
`error`	`nexus: SSE max errors reached, falling back to TTL polling`	`$maxErrors` consecutive stream failures
`error`	`nexus: polling sync failed`	A sync inside the polling window failed
`error`	`nexus: WIF refresh failed, using the configured API key`	A refresh failed and the documented API-key fallback applied
`error`	`nexus: the configured WIF credential source raised`	Your `WifCredentialSource` threw

Structured, not interpolated

Messages are stable strings; values go in the PSR-3 $context array:

$logger->debug('nexus: sync completed', [
    'configs'  => 12,
    'secrets'  => 4,
    'flags'    => 7,
    'key_type' => 'sk',
]);

That is what lets a log aggregator group every sync together and query the counts. A message with its values interpolated into the text is a unique string per occurrence and cannot be grouped or queried at all.

Secrets never appear in log output

Nothing derived from a secret is logged - not the value, and not the key name, which is itself part of what a secret store protects. Sync activity is reported as counts. API keys, session tokens and OIDC tokens never appear either. This is enforced, not merely intended: a permanent test drives a sync carrying both a text-type and a file-type secret through a capturing logger at the most verbose level, and fails if either value or either key name appears anywhere in the output.

A failing logger is contained

A logger that itself throws - a Monolog handler on a full disk, a down syslog target - cannot take an SDK call down with it. Diagnostic writes are contained, so a logging fault degrades logging alone rather than failing the config, secret or WIF operation it was reporting on.

Monolog example

Monolog is the most common PSR-3 implementation in PHP:

use Monolog\Logger;
use Monolog\Handler\StreamHandler;
use WestyxNexus\NexusClient;
use WestyxNexus\NexusConfig;

$logger = new Logger('nexus');
$logger->pushHandler(new StreamHandler('php://stderr', Logger::DEBUG));

$client = NexusClient::create(new NexusConfig(
    baseUrl: $_ENV['NEXUS_URL'],
    apiKey:  $_ENV['NEXUS_API_KEY'],
    logger:  $logger,
));

To route SDK logs to a dedicated channel:

$logger = new Logger('nexus');
$logger->pushHandler(new StreamHandler('/var/log/nexus-sdk.log', Logger::INFO));

Symfony Dependency Injection

In a Symfony application, inject the LoggerInterface via DI:

# config/services.yaml
services:
    WestyxNexus\NexusClient:
        factory: ['WestyxNexus\NexusClient', 'create']
        arguments:
            - '@App\Config\NexusConfigFactory'
            - null
        calls: []

    App\Config\NexusConfigFactory:
        arguments:
            $logger: '@monolog.logger.nexus'

Or in a factory service:

// src/Config/NexusClientFactory.php

namespace App\Config;

use Psr\Log\LoggerInterface;
use WestyxNexus\NexusClient;
use WestyxNexus\NexusConfig;

final class NexusClientFactory
{
    public function __construct(private readonly LoggerInterface $logger) {}

    public function create(): NexusClient
    {
        return NexusClient::create(new NexusConfig(
            baseUrl: $_ENV['NEXUS_URL'],
            apiKey:  $_ENV['NEXUS_API_KEY'],
            logger:  $this->logger,
        ));
    }
}

Laravel

Nothing to do: the service provider takes the logger from the container, so SDK output reaches your application log automatically. Set NEXUS_LOG_CHANNEL to keep it on its own channel:

NEXUS_LOG_CHANNEL=nexus

Add that channel to config/logging.php:

'nexus' => [
    'driver' => 'single',
    'path'   => storage_path('logs/nexus.log'),
    'level'  => env('NEXUS_LOG_LEVEL', 'info'),
],

Silencing SDK logs

If you want the SDK to produce no output at all, pass a NullLogger:

use Psr\Log\NullLogger;

$client = NexusClient::create(new NexusConfig(
    baseUrl: $_ENV['NEXUS_URL'],
    apiKey:  $_ENV['NEXUS_API_KEY'],
    logger:  new NullLogger(),
));

NullLogger ships with psr/log, which the SDK already requires, so there is no extra dependency. Alternatively, leave $logger as null (the default) - the SDK omits all logging in that case.

Overview

Backend SDKs

Browser SDKs

OpenFeature Providers

PHP SDK - Custom Logging

Configuration

What the SDK logs

Structured, not interpolated

Secrets never appear in log output

A failing logger is contained

Monolog example

Symfony Dependency Injection

Laravel

Silencing SDK logs

​Configuration

​What the SDK logs

​Structured, not interpolated

​Secrets never appear in log output

​A failing logger is contained

​Monolog example

​Symfony Dependency Injection

​Laravel

​Silencing SDK logs

Configuration

What the SDK logs

Structured, not interpolated

Secrets never appear in log output

A failing logger is contained

Monolog example

Symfony Dependency Injection

Laravel

Silencing SDK logs