Frappe core logging

Frappe Logging & Error Tracking

Three Logging Mechanisms

Mechanism	Storage	Use For
frappe.logger()	File (rotating)	Application logging, debug info, audit trails
frappe.log_error()	Database (Error Log DocType)	Errors visible in admin UI, persistent tracking
frappe.log() / frappe.errprint()	stderr / request-scoped	Quick debugging only (NOT for production)

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Decision Tree

Need to log something?
│
├─ Application logging (info, debug, warnings)?
│  └─ frappe.logger("my_module").info("message")
│     → Writes to sites/{site}/logs/my_module.log
│
├─ Error that admins should see in Desk UI?
│  └─ frappe.log_error(title="Short desc", message=traceback)
│     → Creates Error Log document (queryable, auto-cleanup)
│
├─ Quick debug during development?
│  └─ frappe.errprint(variable) — shows in console
│     → NEVER leave in production code
│
├─ Track all HTTP requests?
│  └─ Set enable_frappe_logger: true in site_config.json
│     → Logs to frappe.web.log
│
├─ Performance monitoring?
│  └─ Set monitor: true in site_config.json
│     → Logs to monitor.json.log (JSON, per-request metrics)
│
└─ External error tracking (Sentry)?
   └─ Set FRAPPE_SENTRY_DSN environment variable
      → Auto-captures unhandled exceptions

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Quick Reference: frappe.logger()

# Get a logger for your module (ALWAYS specify module name)
logger = frappe.logger("my_app")

# Standard Python logging levels
logger.debug("Detailed diagnostic info")
logger.info("Normal operations: processed 50 records")
logger.warning("Something unexpected but recoverable")
logger.error("Operation failed", exc_info=True)
logger.critical("System-level failure")

# Full signature
frappe.logger(
    module=None,          # Logger name + log filename
    with_more_info=False, # Auto-log request form_dict
    allow_site=True,      # Log under site's logs/ directory
    filter=None,          # Custom logging.Filter
    max_size=100_000,     # Max bytes per log file (100KB default)
    file_count=20         # Rotated files retained (20 default)
)

Log location: sites/{site}/logs/{module}.log Rotation: RotatingFileHandler — 100KB per file, 20 backups (~2MB total per logger)

Default Log Levels

Mode	Level	Effect
Development (_dev_server)	WARNING	Debug/info suppressed
Production	ERROR	Only errors and above

# Change level dynamically
frappe.utils.logger.set_log_level("DEBUG")

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Quick Reference: frappe.log_error()

# ALWAYS use keyword arguments (title/message can swap otherwise)
frappe.log_error(
    title="Payment gateway timeout",          # Short description (140 chars max)
    message=frappe.get_traceback(),            # Full error details
    reference_doctype="Payment Entry",        # Related DocType
    reference_name="PE-00001"                 # Related document
)

# Minimal — auto-captures current traceback
try:
    risky_operation()
except Exception:
    frappe.log_error(title="Operation failed")

Error Log cleanup: Auto-deletes after 30 days. Manual: frappe.whitelist: clear_error_logs()

Auto-Captured Exceptions

Unhandled exceptions (HTTP 500+) are automatically logged to Error Log.

Excluded from auto-capture:

• frappe.AuthenticationError
• frappe.CSRFTokenError
• frappe.SecurityException
• frappe.InReadOnlyMode

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Production Configuration

site_config.json Keys

Key	Value	Effect
enable_frappe_logger	true	HTTP request logging → frappe.web.log
logging	2	Log all SQL queries (debug only!)
monitor	true	Request/job metrics → monitor.json.log
disable_error_snapshot	true	Disable auto-capture of exceptions

Environment Variables

Variable	Effect
FRAPPE_STREAM_LOGGING=1	Log to stderr instead of files
FRAPPE_SENTRY_DSN=<dsn>	Enable Sentry error tracking
ENABLE_SENTRY_DB_MONITORING	Track SQL queries in Sentry
SENTRY_TRACING_SAMPLE_RATE	Performance tracing rate (0.0-1.0)

Production Log Files

File	Content
logs/web.error.log	HTTP errors (supervisor)
logs/web.log	Gunicorn stdout
logs/worker.error.log	Background job errors
logs/frappe.log	Default frappe logger
logs/frappe.web.log	HTTP request metadata
logs/monitor.json.log	Performance metrics (JSON)
sites/{site}/logs/*.log	Per-site application logs

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Anti-Patterns

NEVER	ALWAYS	Why
print("debug info")	frappe.logger("mod").info(...)	print() disappears in production
frappe.log_error("info msg")	frappe.logger().info(...)	log_error creates Error Log docs, clutters admin UI
frappe.logger() (no module)	frappe.logger("my_module")	No-module mixes with framework logs
frappe.log_error(title, msg) positional	frappe.log_error(title=t, message=m)	Positional args can swap (known quirk)
Log passwords/tokens	Mask sensitive data	SiteContextFilter only masks form_dict
frappe.log() in production	frappe.logger()	frappe.log() is debug-only, request-scoped
Leave logging=2 in prod	Only during debugging	Logs ALL SQL queries, massive I/O

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Version Differences

Feature	v14	v15+
frappe.logger()	Yes	Yes
frappe.log_error()	Yes	+ defer_insert kwarg
Error Log trace_id	--	Added
Error Log metadata	--	JSON request/job context
Error snapshots	File-based + scheduled collection	Direct DB insert
Sentry integration	Basic	Enhanced (DB monitoring, profiling)
guess_exception_source()	--	Identifies which app caused error
FRAPPE_STREAM_LOGGING	Yes	Yes

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Reference Files

• Logger API & Patterns — frappe.logger() advanced usage
• Error Tracking — Error Log, Sentry, monitoring