psr/log(PSR-3) extensions for PHPStan

struggle-for-php/sfp-phpstan-psr-log is extra strict and opinionated psr/log (psr-3) rules for PHPStan.

• PHPStan
• PSR-3: Logger Interface - PHP-FIG
• PSR-3 Meta Document

Installation

To use this extension, require it in Composer:

composer require --dev struggle-for-php/sfp-phpstan-psr-log

Manual installation

include extension.neon & rules.neon in your project's PHPStan config:

includes:
    - vendor/struggle-for-php/sfp-phpstan-psr-log/rules.neon

Recommendation Settings

Write these parameters to your project's phpstan.neon.

parameters:
    sfpPsrLog:
        enableMessageStaticStringRule: false # default:true
        enableContextRequireExceptionKeyRule: true
        reportContextExceptionLogLevel: 'info'
        contextKeyOriginalPattern: '#\A[A-Za-z0-9-_]+\z#'

Rules

This package provides the following rules.

PlaceholderCharactersRule

Placeholder names SHOULD be composed only of the characters A-Z, a-z, 0-9, underscore _, and period .

📌 error identifier
sfpPsrLog.placeholderCharactersInvalidChar

• reports when placeholder in $message characters are not, A-Z, a-z, 0-9, underscore _, and period .

// bad
$logger->info('message are {foo-hyphen}');

📌 error identifier
sfpPsrLog.placeholderCharactersDoubleBraces

• reports when double braces pair {{ }} are used.

// bad
$logger->info('message are {{foo}}');

PlaceholderCorrespondToKeysRule

Placeholder names MUST correspond to keys in the context array.

📌 error identifier
sfpPsrLog.placeholderCorrespondToKeysMissedContext

• reports when placeholder exists in message, but $context parameter is missed.

// bad
$logger->info('message has {nonContext} .');

📌 error identifier
sfpPsrLog.placeholderCorrespondToKeysMissedKey

• reports when placeholder exists in message, but key in $context does not exist against them.

// bad
$logger->info('user {user_id} gets an error {error} .', ['user_id' => $user_id]);

ContextKeyRule

Note

PSR-3 has no provisions for array keys, but this is useful in many cases.

📌 error identifier
sfpPsrLog.contextKeyNonEmptyString

• reports when context key is not non-empty-string.

// bad
[123 => 'foo']`, `['' => 'bar']`, `['baz']

📌 error identifier
sfpPsrLog.contextKeyOriginalPattern

• reports when context key is not matched you defined pattern.
  • if contextKeyOriginalPattern parameter is not set, this check would be ignored.

Configuration

• You can set specific key pattern by regex.(preg_match())

parameters:
    sfpPsrLog:
        contextKeyOriginalPattern: '#\A[A-Za-z0-9-]+\z#'

ContextRequireExceptionKeyRule

Note

This is not a rule for along with PSR-3 specification, but provides best practices.

📌 error identifier
sfpPsrLog.contextRequireExceptionKey

• It forces exception key into context parameter when current scope has \Throwable object.

Example

<?php
/** @var \Psr\Log\LoggerInterface $logger */
try {
    //
} catch (LogicException $exception) {
    $logger->warning("foo");
}

$ ../vendor/bin/phpstan analyse
Note: Using configuration file /tmp/your-project/phpstan.neon.
 2/2 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ -------------------------------------------------------------
  Line   Demo.php
 ------ -------------------------------------------------------------
  6      Parameter $context of logger method Psr\Log\LoggerInterface::warning() requires \'exception\' key. Current scope has Throwable variable - $exception
 ------ -------------------------------------------------------------


 [ERROR] Found 1 error

Configuration

• You can set the minimum required level to report. (default level is debug)

parameters:
    sfpPsrLog:
        reportContextExceptionLogLevel: 'warning'

Then, debug| info | notice LogLevel is ignored for report.

} catch (\Exception $e) {
  $logger->info('more info'); // allow
  $logger->warning($e->getMessage(), ['exception' => $e]);
}

• If you want to enable this rule, please add enableContextRequireExceptionKeyRule as true.

parameters:
    sfpPsrLog:
        enableContextRequireExceptionKeyRule: true

ContextTypeRule

Note

This rule validates that the $context parameter has the correct type according to PSR-3 specification.

📌 error identifier
sfpPsrLog.contextType

• reports when $context parameter type does not match the expected type.
  • The default expected type is array{exception?: Throwable} according to PSR-3.

// bad
$logger->info('message', ['exception' => 'string value']); // exception must be Throwable

Configuration

• If you want to disable this rule, please add enableContextTypeRule as false.

parameters:
    sfpPsrLog:
        enableContextTypeRule: false

Advanced: Custom Context Type Provider

You can enforce stricter context types by implementing ContextTypeProviderInterface and injecting it via dependency injection.

• Example: Restricting to specific context keys

<?php
// src/YourCustomContextTypeProvider.php

use PHPStan\Type\ArrayType;
use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
use PHPStan\Type\Constant\ConstantStringType;
use PHPStan\Type\ObjectType;
use PHPStan\Type\StringType;
use PHPStan\Type\Type;
use Sfp\PHPStan\Psr\Log\TypeProvider\ContextTypeProviderInterface;

final class YourCustomContextTypeProvider implements ContextTypeProviderInterface
{
    public function getType(): Type
    {
        $builder = ConstantArrayTypeBuilder::createEmpty();

        // Define allowed context keys with their types
        $builder->setOffsetValueType(
            new ConstantStringType('user_id'),
            new StringType(),
            true // optional
        );
        $builder->setOffsetValueType(
            new ConstantStringType('exception'),
            new ObjectType(\Throwable::class),
            true // optional
        );

        return $builder->getArray();
    }
}

Configure in phpstan.neon:

services:
    yourCustomContextTypeProvider:
        class: YourCustomContextTypeProvider

    contextTypeProviderResolver:
        class: Sfp\PHPStan\Psr\Log\TypeProviderResolver\AnyScopeContextTypeProviderResolver
        arguments:
            contextTypeProvider: @yourCustomContextTypeProvider

    -
        class: Sfp\PHPStan\Psr\Log\Rules\ContextTypeRule
        arguments:
            contextTypeProviderResolver: @contextTypeProviderResolver
        tags:
            - phpstan.rules.rule

This allows you to enforce project-specific context types, such as structured logging schemas (e.g., BigQuery) or custom application requirements.

MessageStaticStringRule

📌 error identifier
sfpPsrLog.messageNotStaticString

• reports when $message is not static string value.

// bad
$logger->info(sprintf('Message contains %s variable', $var));

Configuration

• If you want to disable this rule, please add enableMessageStaticStringRule as false.

parameters:
    sfpPsrLog:
        enableMessageStaticStringRule: false

LogMethodLevelRule

Implementors MUST implement the following interface, which describes the eight methods to write logs to the eight RFC 5424 levels (debug, info, notice, warning, error, critical, alert, emergency). — PSR-3 Logger Interface

📌 error identifier
sfpPsrLog.logMethodLevel

• reports when the $level parameter of log() method is not a valid PSR-3 log level.
  • Valid log levels: emergency, alert, critical, error, warning, notice, info, debug

// bad
$logger->log('panic', 'message'); // 'panic' is not a valid PSR-3 log level
$logger->log(100, 'message'); // level must be a string

Configuration

• If you want to disable this rule, please add enableLogMethodLevelRule as false.

parameters:
    sfpPsrLog:
        enableLogMethodLevelRule: false