Open-Source Observability · symfony

monolog-bundle

MonologBundle integrates the Monolog logging library into Symfony applications, providing centralized log management and flexible output handling. It is an official Symfony package maintained by the framework team and widely used in production PHP applications.

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Source: GitHub — github.com/symfony/monolog-bundle

2.9k

GitHub stars

243

Forks

PHP

Primary language

MIT

License (OSI-approved)

Key facts

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Field	Value
Repository	symfony/monolog-bundle
Owner	symfony
Primary language	PHP
License	MIT — OSI-approved
Stars	2.9k
Forks	243
Open issues	48
Latest release	v4.0.2 (2026-04-02)
Last updated	2026-07-03
Source	https://github.com/symfony/monolog-bundle

What monolog-bundle is

MonologBundle acts as a Symfony service container wrapper around Monolog, enabling declarative logger configuration, multiple handlers (file, stream, syslog, email), and log level filtering. It integrates logging into the Symfony request lifecycle and DI container for easy injection into controllers and services.

Quickstart

Get the monolog-bundle source

Clone the repository and explore it locally.

terminalbash

1git clone https://github.com/symfony/monolog-bundle.git2cd monolog-bundle3# follow the project's README for install & configuration

Need it deployed, integrated, or customized instead? DEV.co ships production installs.

Best use cases

Centralized Application Logging in Symfony Projects

Use MonologBundle to aggregate logs from all application components (controllers, services, kernel events) into configurable handlers. Ideal for production monitoring, debugging, and compliance audit trails.

Multi-Environment Log Management

Configure environment-specific handlers (e.g., file logging in development, syslog/Sentry in production) via Symfony configuration files. Allows zero-code changes across deployment stages.

Integration with External Monitoring and Alerting

Route logs to third-party services (Sentry, Datadog, ELK stack) via Monolog handlers without modifying application code. Supports structured logging for easier parsing and correlation.

Implementation considerations

Configuration is declarative (YAML/XML/PHP) in Symfony config files; logging strategy should be defined early and versioned alongside application code.
Handlers must be configured explicitly for each desired output (file, syslog, email, third-party service); default setup logs to stderr/stdout only.
Log levels and channel-specific routing can be complex in multi-tenant or microservice architectures; requires clear naming conventions.
Performance impact depends on handler choice; file I/O is synchronous by default; consider buffering or async handlers for high-load scenarios.
Development vs. production configurations should be tested early; log verbosity can lead to disk space issues if not monitored.

When to avoid it — and what to weigh

Not Using Symfony Framework — MonologBundle is tightly coupled to Symfony's DI container and configuration system. For non-Symfony PHP applications, use Monolog directly or alternative standalone loggers.
Very High-Volume Logging Requirements — Synchronous logging in MonologBundle can create I/O bottlenecks at scale. Requires custom handler configuration (e.g., buffering, async queuing) for high-throughput scenarios; not baked in.
Simple or Minimal Logging Needs — For applications needing only basic file or console logging, MonologBundle adds overhead and configuration complexity. Consider simpler alternatives or direct PHP error logging.
Long-Term Support or Stability Concerns — While actively maintained, MonologBundle depends on Symfony major version releases. Projects with strict compatibility freezes must track Symfony LTS versions and bundle releases carefully.

License & commercial use

MonologBundle is released under the MIT License, which permits commercial use, modification, and redistribution with no warranty.

MIT License permits unrestricted commercial use, including in proprietary software, provided the license and copyright notice are retained. No patent grants or warranties implied. Suitable for commercial deployment without licensing concerns.

DEV.co evaluation signals

Editorial assessment — not user reviews. Directional, with an explicit confidence level.

Signal	Assessment
Maintenance	Active
Documentation	Strong
License clarity	Clear
Deployment complexity	Low
DEV.co fit	Good
Assessment confidence	High

Security considerations

Log handlers may expose sensitive data (passwords, tokens, PII) if not configured carefully. Use Monolog processors to redact or sanitize sensitive fields. File-based logs require file system access controls. Third-party handler integrations (Sentry, Datadog) should be reviewed for compliance requirements. No known vulnerabilities in current release, but security posture depends on handler configuration and Monolog version alignment.

Alternatives to consider

PSR-3 Logger (php-fig/log) with custom handler

Lightweight, framework-agnostic interface; suitable if avoiding MonologBundle overhead or using multiple PSR-3 implementations.

Monolog (direct use without bundle)

Full control over configuration and instantiation; viable for non-Symfony PHP projects or when avoiding Symfony DI overhead.

Error log / Native PHP logging

Minimal setup, suitable for simple logging; lacks flexibility and structured output but avoids external dependencies.

Software development agency

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monolog-bundle FAQ

Can I use MonologBundle outside Symfony?

No. MonologBundle is tightly integrated into Symfony's service container and configuration system. Use Monolog directly instead.

Does MonologBundle support async/non-blocking logging?

Not natively. By default, logging is synchronous. You can configure custom handlers (e.g., RabbitMQ, Redis) to defer I/O, but this requires manual setup.

How do I log to multiple destinations simultaneously?

Configure multiple handlers in the bundle's configuration file. Each handler processes the log record independently, allowing file + Sentry + syslog in parallel.

Is there a performance impact?

Minimal for typical workloads (file logging). I/O-bound handlers (email, network calls) can cause latency; use buffering or async routing in high-volume scenarios.

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