Frappe Core Logging Agent Skill

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) |

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

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")

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

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 |

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 |

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 |

Reference Files

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