Renttek Log Formatters

Renttek_LogFormatters is a small Magento 2 utility module that provides reusable Monolog formatters, decorators, and file handlers for structured logging.

All formatters in this module format the Monolog record context. This keeps the log output predictable and makes it easy to log structured payloads from Magento code.

Included classes

Formatters

• Renttek\LogFormatters\Logger\Formatter\JsonLineFormatter
• Renttek\LogFormatters\Logger\Formatter\CsvFormatter
• Renttek\LogFormatters\Logger\Formatter\LogfmtFormatter

Decorators

• Renttek\LogFormatters\Logger\Formatter\Decorator\MaskContextDecorator
• Renttek\LogFormatters\Logger\Formatter\Decorator\DateTimeFormatterDecorator

Helper formatter for decorator chains

• Renttek\LogFormatters\Logger\Formatter\Builder\DecoratorChainFormatter

File handlers

• Renttek\LogFormatters\Logger\Handler\JsonLineFileHandler
• Renttek\LogFormatters\Logger\Handler\CsvFileHandler
• Renttek\LogFormatters\Logger\Handler\LogfmtFileHandler

JsonLineFormatter

Writes one JSON object per line.

Example di.xml

<virtualType name="Vendor\Module\Logger\Handler\ApiLogHandler" type="Renttek\LogFormatters\Logger\Handler\JsonLineFileHandler">
    <arguments>
        <argument name="fileName" xsi:type="string">/var/log/api.log</argument>
    </arguments>
</virtualType>

<type name="Vendor\Module\Logger\ApiLogger">
    <arguments>
        <argument name="name" xsi:type="string">api</argument>
        <argument name="handlers" xsi:type="array">
            <item name="default" xsi:type="object">Vendor\Module\Logger\Handler\ApiLogHandler</item>
        </argument>
    </arguments>
</type>

Example output

{"request_id":"abc123","status":200,"path":"/rest/V1/orders"}
{"request_id":"def456","status":500,"path":"/rest/V1/orders","error":"Upstream timeout"}

CsvFormatter

Writes the context values as a single CSV row. Arrays and nested structures are JSON-encoded into one cell. The separator, enclosure, and escape characters are configurable through the constructor and default to ,, ", and \.

Example di.xml

<virtualType name="Vendor\Module\Logger\Handler\ExportLogHandler" type="Renttek\LogFormatters\Logger\Handler\CsvFileHandler">
    <arguments>
        <argument name="fileName" xsi:type="string">/var/log/export.csv</argument>
        <argument name="separator" xsi:type="string">;</argument>
        <argument name="enclosure" xsi:type="string">"</argument>
        <argument name="escape" xsi:type="string">\</argument>
    </arguments>
</virtualType>

<type name="Vendor\Module\Logger\ExportLogger">
    <arguments>
        <argument name="name" xsi:type="string">export</argument>
        <argument name="handlers" xsi:type="array">
            <item name="default" xsi:type="object">Vendor\Module\Logger\Handler\ExportLogHandler</item>
        </argument>
    </arguments>
</type>

Example output

2026-04-25T13:45:00+00:00;orders;150;2
2026-04-25T13:50:00+00:00;customers;80;0

LogfmtFormatter

Writes the context as key=value pairs in logfmt format. Values with spaces or special characters are quoted.

Example di.xml

<virtualType name="Vendor\Module\Logger\Handler\SyncLogHandler" type="Renttek\LogFormatters\Logger\Handler\LogfmtFileHandler">
    <arguments>
        <argument name="fileName" xsi:type="string">/var/log/sync.logfmt</argument>
    </arguments>
</virtualType>

<type name="Vendor\Module\Logger\SyncLogger">
    <arguments>
        <argument name="name" xsi:type="string">sync</argument>
        <argument name="handlers" xsi:type="array">
            <item name="default" xsi:type="object">Vendor\Module\Logger\Handler\SyncLogHandler</item>
        </argument>
    </arguments>
</type>

Example output

job=inventory_sync status=ok duration_ms=231 store=default
job=inventory_sync status=failed duration_ms=912 error="Connection reset by peer"

MaskContextDecorator

Decorates another formatter and replaces configured context fields with a fixed mask value before the wrapped formatter formats the record.

Example di.xml

<virtualType name="Vendor\Module\Logger\Formatter\MaskedJsonFormatter"
             type="Renttek\LogFormatters\Logger\Formatter\Decorator\MaskContextDecorator">
    <arguments>
        <argument name="formatter" xsi:type="object">Renttek\LogFormatters\Logger\Formatter\JsonLineFormatter</argument>
        <argument name="fieldsToMask" xsi:type="array">
            <item name="authorization" xsi:type="string">authorization</item>
            <item name="token" xsi:type="string">token</item>
            <item name="password" xsi:type="string">password</item>
        </argument>
        <argument name="maskValue" xsi:type="string">[redacted]</argument>
    </arguments>
</virtualType>

Example output

{"endpoint":"/rest/V1/customers","authorization":"[redacted]","token":"[redacted]","customer_id":42}
{"endpoint":"/rest/V1/customers","password":"[redacted]","email":"customer@example.com"}

DateTimeFormatterDecorator

Decorates another formatter and converts any DateTimeInterface values in the context to strings before the wrapped formatter formats the record. The output format is configurable and defaults to DATE_ATOM.

Example di.xml

<virtualType name="Vendor\Module\Logger\Formatter\DateTimeJsonFormatter"
             type="Renttek\LogFormatters\Logger\Formatter\Decorator\DateTimeFormatterDecorator">
    <arguments>
        <argument name="formatter" xsi:type="object">Renttek\LogFormatters\Logger\Formatter\JsonLineFormatter</argument>
        <argument name="format" xsi:type="string">Y-m-d H:i:s</argument>
    </arguments>
</virtualType>

Example output

{"job":"catalog_sync","started_at":"2026-04-25 14:30:00","finished_at":"2026-04-25 14:31:15"}

DecoratorChainFormatter

DecoratorChainFormatter helps keep di.xml flatter when you want to apply multiple decorators to one formatter. You provide one base formatter and a list of decorator configurations. Decorators are applied in the same order as they are listed in di.xml.

Example di.xml

<virtualType name="Vendor\Module\Logger\Formatter\ApiFormatter"
             type="Renttek\LogFormatters\Logger\Formatter\Builder\DecoratorChainFormatter">
    <arguments>
        <argument name="formatter" xsi:type="object">Renttek\LogFormatters\Logger\Formatter\JsonLineFormatter</argument>
        <argument name="decorators" xsi:type="array">
            <!-- decorator can be a simple FQDN -->
            <item name="datetime" xsi:type="object">Renttek\LogFormatters\Logger\Formatter\Decorator\DateTimeFormatterDecorator</item>
            <!-- Or a configuration with a class and it's parameters (to save on virtual types) -->
            <item name="mask" xsi:type="array">
                <item name="class" xsi:type="string">Renttek\LogFormatters\Logger\Formatter\Decorator\MaskContextDecorator</item>
                <item name="fieldsToMask" xsi:type="array">
                    <item name="token" xsi:type="string">token</item>
                    <item name="authorization" xsi:type="string">authorization</item>
                </item>
                <item name="maskValue" xsi:type="string">[redacted]</item>
            </item>
        </argument>
    </arguments>
</virtualType>

<virtualType name="Vendor\Module\Logger\Handler\ApiLogHandler"
             type="Renttek\LogFormatters\Logger\Handler\JsonLineFileHandler">
    <arguments>
        <argument name="fileName" xsi:type="string">/var/log/api.log</argument>
        <argument name="formatter" xsi:type="object">Vendor\Module\Logger\Formatter\ApiFormatter</argument>
    </arguments>
</virtualType>

Example output

{"endpoint":"/rest/V1/orders","requested_at":"2026-04-25T14:30:00+00:00","authorization":"[redacted]","token":"[redacted]"}

Notes

• The file handlers write to Magento's var/log directory when you pass a path such as /var/log/example.log as fileName.
• The JSON, CSV, and logfmt handlers accept an optional formatter constructor argument, so decorated formatters can be injected through di.xml.
• CsvFileHandler also accepts separator, enclosure, and escape constructor arguments.