README

PSR-3 compatible logger that outputs structured JSON log lines.

Requirements

PHP ^8.2
psr/log ^3.0

Installation

composer require philiprehberger/php-structured-logger

Usage

Basic logging

use PhilipRehberger\StructuredLogger\JsonLogger;

// Log to stdout (default)
$logger = new JsonLogger();
$logger->info('Application started');

// Log to a file
$logger = new JsonLogger(output: '/var/log/app.log');
$logger->info('User logged in', ['user_id' => 42]);

Logging with context

$logger = new JsonLogger(output: 'php://stderr');

$logger->error('Payment failed', [
    'order_id' => 'ORD-123',
    'amount' => 49.99,
    'currency' => 'USD',
]);

Output:

{"timestamp":"2026-03-13T10:00:00+00:00","level":"error","message":"Payment failed","channel":"app","context":{"order_id":"ORD-123","amount":49.99,"currency":"USD"}}

Sensitive data redaction

By default, the following context keys are automatically redacted: password, token, secret, api_key, authorization, credit_card. Redaction applies recursively to nested arrays.

$logger = new JsonLogger();

$logger->info('Auth attempt', [
    'username' => 'alice',
    'password' => 's3cret',
    'token' => 'abc123',
]);
// password and token values replaced with "[REDACTED]"

You can provide a custom list of keys to redact:

$logger = new JsonLogger(
    redactKeys: ['password', 'ssn', 'credit_card'],
);

Custom channel

Use the channel parameter to identify different services or application components:

$logger = new JsonLogger(
    output: '/var/log/payments.log',
    channel: 'payments',
);

$logger->info('Payment processed');
// {"timestamp":"...","level":"info","message":"Payment processed","channel":"payments"}

Output format

Each log line is a single JSON object with the following fields:

Field	Type	Description
`timestamp`	string	ISO 8601 timestamp
`level`	string	PSR-3 log level
`message`	string	Log message
`channel`	string	Application/service name (default: `app`)
`context`	object	Additional data (omitted when empty)

API

`JsonLogger`

Parameter	Type	Default	Description
`output`	`string`	`'php://stdout'`	File path or PHP stream wrapper
`channel`	`string`	`'app'`	Application/service identifier
`redactKeys`	`string[]`	`['password', 'token', 'secret', 'api_key', 'authorization', 'credit_card']`	Context keys to redact

All PSR-3 log methods are available: emergency(), alert(), critical(), error(), warning(), notice(), info(), debug(), log().

`LogEntry`

Immutable value object representing a single log entry. Implements JsonSerializable.

Method	Returns	Description
`toArray()`	`array`	Entry as associative array
`toJson()`	`string`	Entry as JSON string
`jsonSerialize()`	`array`	For `json_encode()` support

Development

composer install
vendor/bin/phpunit
vendor/bin/pint --test
vendor/bin/phpstan analyse

License

MIT

philiprehberger / php-structured-logger

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