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SimpleLogger

SimpleLogger is a PHP library to write logs. It has simple, straightforward defaults with additional customization hooks.

• Drivers: Syslog, stdout, stderr and text file
• Compatible with PSR-3 Standard Logger Interface
• Requirements: PHP >= 8.1
• License: MIT

Usage

Installation

Syslog

Send log messages to Syslog:

Files

Send log messages to a text file:

Stdout and Stderr

These loggers will write to STDOUT or STDERR; i.e. php://stdout or php://stderr. Stdout is very commonly used for Docker and/or Kubernetes.

Minimum log level for loggers

In this example, only messages with the level >= "error" will be sent to the Syslog handler but everything is sent to the File handler:

The minimum log level is LogLevel::DEBUG by default.

Formatting

Starting in 3.0.0, message format customization can be accomplished in several ways:

• Initialize DefaultFormatter, change its format with setFormat(string $format), and pass it to your logger's constructor
• Use a different bundled formatter, such as LogFmtFormatter
• Create a class that implements FormatterInterface and pass that to your logger's constructor

DefaultFormatter

The format provided MUST include %s, which is where the actual interpolated message will be placed. Formats MAY include {date} and/or {level}, which are placeholders for the timestamp and log level respectively.

The default format is [{date}] [{level}] %s, which will result in a log message like this:

The date defaults to ATOM format, but can also be customized via setDateFormat(string $format) using any format string that date() accepts.

By default, this will ignore exception keys and perform normal message interpolation. By calling setRenderExceptions(true), the equivalent of (string) $context['exception'] will be appended to the log message if that key is set, so long as that value is Throwable.

LogFmt

The LogFmtFormatter will write logs in logfmt. By default, the msg, level, and ts keys will be set, and any values in context that are not interpolated will be added as additional key/value pairs. Exceptions will also be rendered, in exception_message, exception_type, and exception_stacktrace per OTel conventions.

Any values that resolve to empty strings, or cannot be cast to a string (arrays, objects without __toString()) will be removed.

[!TIP] Any interpolated values from context will not be put in the key/value pairs. To make the most out of structured log formats such as logfmt, limit interpolation keys in the coded message.

For example, prefer this:

over this:

Custom FormatterInterface

If you need deeper customization, such as log enrichment or more major format shifts, a custom FormatterInterface is the way to go. Doing so requires your own interpolation logic, as well as any other message enrichment or formatting. You'll be passed the same (unmodified) parameters as LoggerInterface::log() gets, and are responsible for transforming these values into a string.

Sending to multiple loggers

Send log messages to multiple PSR-3 loggers with ChainLogger():

The ChainLogger supports a log level, in addition to loggers it relays to. This is configuable only by a constructor parameter. If a log entry is less severe than the configured level, none of the loggers in the chain will receive the message. Those loggers may opt to do additional filtering.