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Logger

License

Overview

Emits PSR-3 structured logs for PHP, with each entry carrying timestamp, component, correlation id, level, and a structured data payload. Supports pluggable redactions for sensitive fields such as passwords, emails, phone numbers, and identity documents, plus a severity threshold that drops quieter entries before they are rendered. Built for consumption by log aggregators and SIEM pipelines in production environments.

Redaction is composable and split in two. The Redactions namespace holds strategies named after the kind of data they protect, ready to use. Nested under it, Redactions\Rules holds the general ones, named after the rule they apply: how much of a value stays visible, which branch of the payload a redaction reaches, which fields survive at all, and which patterns are masked wherever they appear.

Installation

composer require tiny-blocks/logger

How to use

Basic logging

Create a logger with StructuredLogger::create() and use the fluent builder to configure it. All PSR-3 log levels are supported: debug, info, notice, warning, error, critical, alert, and emergency.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withComponent(component: 'order-service')
    ->build();

$logger->info(message: 'order.placed', context: ['orderId' => 42]);

Output (default template, written to STDERR):

2026-02-21T16:00:00+00:00 component=order-service correlation_id= level=INFO key=order.placed data={"orderId":42}

Correlation tracking

A correlation ID can be attached at creation time or derived later using withContext. The original instance is never mutated.

At creation time

<?php

declare(strict_types=1);

use TinyBlocks\Logger\LogContext;
use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withContext(context: LogContext::from(correlationId: 'req-abc-123'))
    ->withComponent(component: 'payment-service')
    ->build();

$logger->info(message: 'payment.started', context: ['amount' => 100.50]);

Derived from an existing logger

<?php

declare(strict_types=1);

use TinyBlocks\Logger\LogContext;
use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withComponent(component: 'payment-service')
    ->build();

$contextual = $logger->withContext(context: LogContext::from(correlationId: 'req-abc-123'));

$contextual->info(message: 'payment.started', context: ['amount' => 100.50]);

Minimum log level

Entries below the configured level are discarded before redaction and formatting run. The default is LogLevel::DEBUG, which writes everything.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\LogLevel;
use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withComponent(component: 'order-service')
    ->withMinimumLevel(minimumLevel: LogLevel::WARNING)
    ->build();

$logger->info(message: 'order.placed');    # discarded
$logger->warning(message: 'stock.low');    # written

LogLevel also answers severity questions on its own:

LogLevel::CRITICAL->isAtLeast(threshold: LogLevel::WARNING);

Sensitive data redaction

Redaction is optional and configurable. Every strategy implements Redaction, and strategies compose: the logger applies each one in the order it was registered.

Strategy catalog

Strategies live in two namespaces. Redactions holds the ready-made ones, each named after the kind of data it protects. Rules holds the general ones, each named after the rule it applies, for whatever the ready-made set does not cover.

TinyBlocks\Logger\Redactions, by kind of data:

Strategy Keeps visible Default field
DocumentRedaction Trailing characters document
EmailRedaction Local part prefix and full domain email
PhoneRedaction Trailing characters phone
NameRedaction Leading characters name
PasswordRedaction Nothing password

TinyBlocks\Logger\Redactions\Rules, by rule:

Strategy Keeps visible Typical use
VisibleEdgesRedaction Leading and trailing characters Any value needing a custom window
WordwiseRedaction The edges of every word Full names, multi word labels
FullMaskRedaction Nothing Secrets, free text, addresses, user agents
ScopedRedaction Delegates within one parent field Field names that repeat with different meanings
AllowedFieldsRedaction Only the listed fields Deny by default, so a new field is masked until allowed
RemovedFieldsRedaction Nothing, the field itself is gone Stack traces, payment codes
PatternRedaction Everything except the matches Sensitive data embedded in free text

Choosing a mask

The general primitives take a Mask, which decides how the hidden portion is rendered.

Factory Renders Reveals the original length
Mask::proportional() One mask character per hidden character Yes
Mask::fixed(length: 8) The same number of characters every time No
Mask::preservingSeparators() Letters and digits masked, everything else preserved Partially 
<?php

declare(strict_types=1);

use TinyBlocks\Logger\Mask;
use TinyBlocks\Logger\Redactions\Rules\VisibleEdgesRedaction;

# "+5511999887766" → "+5511*****7766"
VisibleEdgesRedaction::from(
    mask: Mask::proportional(),
    fields: ['phone'],
    visiblePrefixLength: 5,
    visibleSuffixLength: 4
);

# "01310-100" → "013**-***"
VisibleEdgesRedaction::from(
    mask: Mask::preservingSeparators(),
    fields: ['postal_code'],
    visiblePrefixLength: 3
);

The field-specific strategies use Mask::proportional(), so their output has the width of the original value. When the width itself is sensitive, reach for a primitive with Mask::fixed(...).

Field name patterns

Every strategy accepts shell style wildcards in its field list, so a naming convention can be covered without listing each field.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\NameRedaction;

NameRedaction::from(fields: ['*_name'], visiblePrefixLength: 2);
# client_name "João Silva" → "Jo********"
# name        "Maria"      → "Maria" (no match, the pattern requires the underscore)

Values are matched at any depth, and numbers and other scalars are masked as text. When a matched field holds a list, every element is masked, since a list carries values and nothing else. When it holds a map, the map is descended into instead, because its keys carry their own meaning and masking them would destroy operational data. Use ScopedRedaction to reach a specific key inside such a map.

Document redaction

Masks all characters except the last N (default: 3).

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\DocumentRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'kyc-service')
    ->withRedactions(DocumentRedaction::default())
    ->build();

$logger->info(message: 'kyc.verified', context: ['document' => '12345678900']);
# document → "********900"

With custom fields and visible length:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\DocumentRedaction;

DocumentRedaction::from(fields: ['cpf', 'cnpj'], visibleSuffixLength: 5);
# cpf "12345678900"     → "******78900"
# cnpj "12345678000199" → "*********00199"

Email redaction

Preserves the first N characters of the local part (default: 2) and the full domain.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\EmailRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'user-service')
    ->withRedactions(EmailRedaction::default())
    ->build();

$logger->info(message: 'user.registered', context: ['email' => 'john@example.com']);
# email → "jo**@example.com"

With custom fields:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\EmailRedaction;

EmailRedaction::from(fields: ['email', 'contact_email', 'recoveryEmail'], visiblePrefixLength: 2);

Phone redaction

Masks all characters except the last N (default: 4).

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\PhoneRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'notification-service')
    ->withRedactions(PhoneRedaction::default())
    ->build();

$logger->info(message: 'sms.sent', context: ['phone' => '+5511999887766']);
# phone → "**********7766"

With custom fields:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\PhoneRedaction;

PhoneRedaction::from(fields: ['phone', 'mobile', 'whatsapp'], visibleSuffixLength: 4);

Password redaction

Masks the entire value with a fixed-length mask (default: 8 characters). The original value's length is never revealed in the output, preventing information leakage about password size.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\PasswordRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'auth-service')
    ->withRedactions(PasswordRedaction::default())
    ->build();

$logger->info(message: 'login.attempt', context: ['password' => 's3cr3t!']);
# password → "********"

$logger->info(message: 'login.attempt', context: ['password' => '123']);
# password → "********" (same mask regardless of length)

With custom fields and fixed mask length:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\PasswordRedaction;

PasswordRedaction::from(fields: ['password', 'secret', 'token'], fixedMaskLength: 12);
# "s3cr3t!"       → "************"
# "ab"            → "************"
# "long_password" → "************"

Name redaction

Preserves the first N characters (default: 2) and masks the rest.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\NameRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'user-service')
    ->withRedactions(NameRedaction::default())
    ->build();

$logger->info(message: 'user.created', context: ['name' => 'Gustavo']);
# name → "Gu*****"

With custom fields and visible length:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\NameRedaction;

NameRedaction::from(fields: ['name', 'full_name', 'firstName'], visiblePrefixLength: 3);
# "Gustavo"       → "Gus****"
# "Gustavo Freze" → "Gus**********"
# "Maria"         → "Mar**"

Visible edges redaction

The general primitive behind the field-specific strategies. Keeps a window at the head, at the tail, or at both ends.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Mask;
use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\VisibleEdgesRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'payment-service')
    ->withRedactions(
        VisibleEdgesRedaction::from(
            mask: Mask::proportional(),
            fields: ['birth_date'],
            visiblePrefixLength: 4
        )
    )
    ->build();

$logger->info(message: 'payer.registered', context: ['birth_date' => '1990-07-21']);
# birth_date → "1990******"

A negative visible length is rejected with NegativeVisibleLength.

Wordwise redaction

Masks each word of the value on its own, so a full name stays readable as a shape instead of collapsing into a single run of mask characters.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Mask;
use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\WordwiseRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'user-service')
    ->withRedactions(
        WordwiseRedaction::from(
            mask: Mask::fixed(length: 3),
            fields: ['name', 'holder'],
            visiblePrefixLength: 2
        )
    )
    ->build();

$logger->info(message: 'user.created', context: ['name' => 'Gustavo Freze']);
# name → "Gu*** Fr***"

Full mask redaction

Masks the value entirely. Suited to anything that carries no operational meaning once logged, such as secrets, free text, street addresses, and user agents.

It is the named counterpart of VisibleEdgesRedaction with no visible edge. Both produce the same output, and the separate name exists so the intent reads at the call site, the same way DocumentRedaction and PhoneRedaction are both suffix strategies under two names.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Mask;
use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\FullMaskRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'audit-service')
    ->withRedactions(
        FullMaskRedaction::from(mask: Mask::fixed(length: 8), fields: ['ip', 'user_agent', 'session_id'])
    )
    ->build();

$logger->info(message: 'request.received', context: ['ip' => '10.0.0.1', 'route' => '/v1/users']);
# ip    → "********"
# route → "/v1/users" (unchanged)

commonSecrets() covers the field names that carry secrets across most systems (*token*, *secret*, *api_key*, *password*, *private_key*, credentials, and authorization) with a fixed mask:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redactions\Rules\FullMaskRedaction;

FullMaskRedaction::commonSecrets();
# access_token     → "********"
# client_secret    → "********"
# current_password → "********"

Scoped redaction

Field names repeat across a payload with different meanings. A value under document is an identity document, a value under metadata is an operational marker. Scoping a redaction to its parent keeps the first masked and the second readable.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\DocumentRedaction;
use TinyBlocks\Logger\Redactions\Rules\ScopedRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'payment-service')
    ->withRedactions(
        ScopedRedaction::under(
            parent: 'document',
            redaction: DocumentRedaction::from(fields: ['value'], visibleSuffixLength: 2)
        )
    )
    ->build();

$logger->info(message: 'payment.created', context: [
    'document' => ['type' => 'cpf', 'value' => '12345678901'],
    'metadata' => ['value' => 'operational-marker']
]);
# document.value → "*********01"
# metadata.value → "operational-marker" (unchanged)

The scope applies at any depth, so a document nested under charge is covered by the same rule.

Allowed fields redaction

The inverse of the other strategies, which name what to hide. Naming what to keep removes the leak by omission, since a field added later is masked until it is explicitly allowed. Pair it with ScopedRedaction to apply the allow list to one branch of the payload instead of all of it.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Mask;
use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\AllowedFieldsRedaction;
use TinyBlocks\Logger\Redactions\Rules\ScopedRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'payment-service')
    ->withRedactions(
        ScopedRedaction::under(
            parent: 'address',
            redaction: AllowedFieldsRedaction::from(mask: Mask::fixed(length: 3), fields: ['city', 'state'])
        )
    )
    ->build();

$logger->info(message: 'payment.created', context: [
    'address' => ['city' => 'São Paulo', 'state' => 'BR-SP', 'street' => 'Rua Example', 'number' => '123']
]);
# address.city   → "São Paulo" (allowed)
# address.state  → "BR-SP" (allowed)
# address.street → "***"
# address.number → "***"

Removed fields redaction

Drops the field instead of masking it. Preferred when the field carries no diagnostic value at all, so nothing about the original reaches the log, not even its presence.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\RemovedFieldsRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'error-service')
    ->withRedactions(RemovedFieldsRedaction::from(fields: ['trace', '*_token']))
    ->build();

$logger->error(message: 'request.failed', context: [
    'message' => 'boom',
    'trace'   => '#0 /app/src/Handler.php(42)',
    'nested'  => ['access_token' => 'at-1', 'id' => '7']
]);
# data={"message":"boom","nested":{"id":"7"}}

Pattern redaction

Field-based strategies cannot reach sensitive data embedded in free text: an exception message quoting a document, a stack trace, a URI carrying a query string. Matching on the value instead of the key closes that gap.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\Rules\PatternRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'error-service')
    ->withRedactions(PatternRedaction::from(pattern: '/\d{11}/', replacement: '[REDACTED]'))
    ->build();

$logger->error(message: 'request.failed', context: [
    'message' => 'Document 12345678901 is invalid.',
    'uri'     => '/clients/12345678901'
]);
# message → "Document [REDACTED] is invalid."
# uri     → "/clients/[REDACTED]"

A pattern the regular expression engine rejects raises InvalidRedactionPattern at configuration time, not at the first log call.

Composing multiple redactions

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;
use TinyBlocks\Logger\Redactions\DocumentRedaction;
use TinyBlocks\Logger\Redactions\EmailRedaction;
use TinyBlocks\Logger\Redactions\Rules\FullMaskRedaction;
use TinyBlocks\Logger\Redactions\NameRedaction;
use TinyBlocks\Logger\Redactions\PhoneRedaction;

$logger = StructuredLogger::create()
    ->withComponent(component: 'user-service')
    ->withRedactions(
        NameRedaction::default(),
        EmailRedaction::default(),
        PhoneRedaction::default(),
        DocumentRedaction::default(),
        FullMaskRedaction::commonSecrets()
    )
    ->build();

$logger->info(message: 'user.registered', context: [
    'name'         => 'John',
    'email'        => 'john@example.com',
    'phone'        => '+5511999887766',
    'status'       => 'active',
    'document'     => '12345678900',
    'access_token' => 'at-1'
]);
# name         → "Jo**"
# email        → "jo**@example.com"
# phone        → "**********7766"
# status       → "active" (unchanged)
# document     → "********900"
# access_token → "********"

Custom redaction

Implement the Redaction interface to create your own strategy:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\Redaction;

final readonly class ReversedRedaction implements Redaction
{
    public function redact(array $payload): array
    {
        foreach ($payload as $key => $value) {
            if (is_array($value)) {
                $payload[$key] = $this->redact(payload: $value);
                continue;
            }

            if ($key === 'signature' && is_string($value)) {
                $payload[$key] = strrev($value);
            }
        }

        return $payload;
    }
}

Then add it to the logger:

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withComponent(component: 'auth-service')
    ->withRedactions(new ReversedRedaction())
    ->build();

$logger->info(message: 'user.logged_in', context: ['signature' => 'abc123']);
# signature → "321cba"

Custom log template

The default output template is:

%s component=%s correlation_id=%s level=%s key=%s data=%s

You can replace it with any sprintf compatible template that accepts six string arguments (timestamp, component, correlationId, level, key, data):

<?php

declare(strict_types=1);

use TinyBlocks\Logger\StructuredLogger;

$logger = StructuredLogger::create()
    ->withComponent(component: 'custom-service')
    ->withTemplate(template: "[%s] %s | %s | %s | %s | %s\n")
    ->build();

$logger->info(message: 'custom.event', context: ['value' => 42]);
# [2026-02-21T16:00:00+00:00] custom-service |  | INFO | custom.event | {"value":42}

Testing with the in-memory logger

InMemoryLogger records entries instead of writing them, so a test asserts on what was logged rather than on how it was rendered. Payloads are kept exactly as received, with no redaction and no formatting. Loggers derived through withContext record into the same store, so entries are visible from either instance.

<?php

declare(strict_types=1);

use TinyBlocks\Logger\InMemoryLogger;

$logger = InMemoryLogger::create();

$logger->info(message: 'user.created', context: ['document' => '12345678900']);

$logger->entries()->toArray();
# [['key' => 'user.created', 'level' => 'INFO', 'context' => null, 'payload' => ['document' => '12345678900']]]

FAQ

01. Why does a masked value keep the width of the original?

Only when the strategy asks for it. The field-specific strategies use Mask::proportional(), which emits one character per hidden character, because a support engineer reading **********7766 can still tell a mobile number from a short extension. That convenience costs information: the width of the output is the width of the input.

When the width itself is sensitive, a password being the clearest case, use Mask::fixed(...), which emits the same run every time and is what PasswordRedaction and FullMaskRedaction::commonSecrets() already do.

02. Why scope a redaction to a parent field instead of listing field names?

Because field names are not unique. A payload carries code as a verification code in one branch and as an error code in another, number as a card number in one place and as a page number in a query string in another. A flat list of field names cannot tell them apart, so masking the sensitive one also destroys the diagnostic one.

ScopedRedaction restricts a strategy to the sub payloads found under a given parent, which is the smallest piece of context needed to disambiguate.

03. When should a field be dropped instead of masked?

When the masked value would still be noise. A stack trace, a payment brcode, or a raw user agent tells a reader nothing once masked, and it still costs bytes in every aggregator downstream. RemovedFieldsRedaction removes the key entirely.

Masking stays the right answer whenever the shape of the value carries meaning, for example knowing that a document was present and ended in 900.

04. Why does the logger match field names with wildcards?

Because leaks happen by omission, not by mistake. A payload gains a client_name next to the name that was already covered, and nothing in the configuration reacts. Patterns such as *_name or *token* follow the naming convention rather than the current field list.

For payloads where even that is not enough, AllowedFieldsRedaction inverts the default: everything is masked until it is named.

License

Logger is licensed under MIT.

Contributing

Please follow the contributing guidelines to contribute to the project.

About

Emits PSR-3 structured logs for PHP, with correlation tracking and configurable sensitive data redaction.

packagist.org/packages/tiny-blocks/logger

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