Configuring Logging

1. Setting Log Level

Property	Values	Description
log.level	`debug`, `info`, `warn`, `error`	Global log level for RabbitMQ node
log.level.file	`debug`, `info`, `warn`, `error`	Log level for file output
log.level.console	`debug`, `info`, `warn`, `error`	Log level for console output

Example: Configuring Log Level

log.level: info
log.level.file: debug
log.level.console: warn

2. Configuring Log File

Property	Values	Description
log.file.path	`/var/log/rabbitmq/rabbit.log`	Path to the log file
log.file.level	`info`	Log level for file output (debug, info, warning, error)
log.file.rotation.count	`5`	Number of rotated log files to keep
log.file.rotation.size	`10MB`	Maximum size of log file before rotation

Example: Log File Configuration

log.file.path: /var/log/rabbitmq/rabbit.log
log.file.level: info
log.file.rotation.count: 5
log.file.rotation.size: 10MB

3. Using JSON Logging

Configuration Option	Value	Description
log_json	`true`	Enables JSON logging format
log_json_file	`/var/log/rabbitmq/rabbit.log.json`	Path to the JSON log file

Example: Enabling JSON Logging

[{rabbit, [{log_json, true}, {log_json_file, "/var/log/rabbitmq/rabbit.log.json"}]}].

Note: JSON logs are useful for centralized logging systems and monitoring tools that parse structured data.

4. Filtering Log Categories

Category	Description	Default Level	Notes
amqp	AMQP protocol handling	INFO	Logs AMQP frames and connection events
auth	Authentication and authorization	INFO	Logs login attempts, user permissions
connection	Connection management	INFO	Tracks connection open/close events
channel	Channel operations	INFO	Logs channel creation and closure
queue	Queue operations	INFO	Logs queue declarations, bindings
exchange	Exchange operations	INFO	Logs exchange declarations and bindings
consumer	Consumer handling	INFO	Logs consumer registration and delivery
policy	Policy application	INFO	Logs policy matching and application
mnesia	Mnesia database operations	INFO	Logs internal state changes
disk	Disk I/O operations	INFO	Logs disk usage and file access
memory	Memory usage tracking	INFO	Logs memory allocation and limits
flow	Flow control operations	INFO	Logs flow control state changes
heartbeat	Heartbeat handling	INFO	Logs heartbeat timeouts and intervals
federation	Federation plugin operations	INFO	Logs federation link status and errors
shovel	Shovel plugin operations	INFO	Logs shovel configuration and status
management	Management plugin operations	INFO	Logs API calls and dashboard access
rabbitmq_prometheus	Prometheus metrics logging	INFO	Logs metric collection and export
rabbitmq_tracing	Tracing plugin operations	INFO	Logs tracing configuration and events
rabbitmq_consistent_hash	Consistent hash exchange plugin	INFO	Logs hash calculation and routing
rabbitmq_stream	Stream plugin operations	INFO	Logs stream creation and consumption

Example: Configuring Log Levels in rabbitmq.conf


# Set log level for specific categories
log_levels.amqp = debug
log_levels.auth = warning
log_levels.connection = info

# Enable debug logging for specific components
log_levels.rabbitmq_tracing = debug

Note: Log levels can be set to debug, info, warning, error, or none. Setting a category to none disables all logging for that category.

Warning: Enabling debug logging for all categories can significantly impact performance and disk space usage. It is recommended to use specific category filtering rather than setting all categories to debug.

5. Enabling Connection Logging

Configuration Option	Values	Description
log.connection	`true` \| `false`	Enables or disables connection-level logging. Default is `false`.
log.connection.level	`info` \| `debug` \| `warn` \| `error`	Sets the logging level for connection events. Default is `info`.

Example: Enabling Connection Logging

{"log": {"connection": true, "connection.level": "debug"}}

Note: Connection logging can significantly increase log volume in high-traffic environments.

6. Enabling Channel Logging

Configuration Option	Values	Description
log.console	`true` / `false`	Enable or disable console logging for channels
log.file	`path/to/logfile.log`	Path to the log file for channel events
log.level	`debug`, `info`, `warn`, `error`	Minimum level of messages to log

Example: Enabling Channel Logging in RabbitMQ Configuration

logging:
  console: true
  file: /var/log/rabbitmq/channel.log
  level: debug

Note: Channel logging can significantly impact performance in high-throughput environments. Consider enabling it only for debugging or monitoring specific channels.

7. Logging AMQP Commands

Command	Description	Log Level	Notes
basic.publish	Publishes a message to an exchange	INFO	Logged when a message is successfully published
basic.deliver	Delivers a message to a consumer	INFO	Logged when a message is delivered to a consumer
basic.ack	Acks a delivered message	DEBUG	Logged when a message is acknowledged by the consumer
basic.nack	Nacks a delivered message	DEBUG	Logged when a message is negatively acknowledged by the consumer
basic.reject	Rejects a delivered message	DEBUG	Logged when a message is rejected by the consumer
confirm.select	Enables publisher confirms	INFO	Logged when publisher confirms are enabled
confirm.select	Confirms a published message	INFO	Logged when a published message is confirmed

Example: Enabling AMQP Command Logging

# Enable AMQP command logging in RabbitMQ config
echo 'log.console = true' >> /etc/rabbitmq/rabbitmq.conf
echo 'log.console.level = debug' >> /etc/rabbitmq/rabbitmq.conf
echo 'log.file = /var/log/rabbitmq/rabbit.log' >> /etc/rabbitmq/rabbitmq.conf
echo 'log.file.level = info' >> /etc/rabbitmq/rabbitmq.conf

Note: AMQP command logging can significantly increase log volume and should be used carefully in production environments.

8. Using Syslog

Configuration Option	Values	Description
vm_memory_high_watermark	`0.4`	Percentage of total system memory that triggers memory pressure warnings
vm_memory_high_watermark_persistent	`0.4`	Same as above but for persistent messages
disk_free_limit	`50MB`	Minimum free disk space before triggering warnings

Example: Syslog Configuration in rabbitmq.conf

# Enable logging to syslog
log.console = off
log.syslog = on

# Set log level for syslog
log.syslog.level = info

# Define the facility and priority
log.syslog.facility = local0
log.syslog.priority = notice

Note: Ensure that your system's syslog daemon is configured to handle messages from RabbitMQ. The local0 facility is commonly used for application-specific logs.

Warning: Misconfiguring syslog can lead to loss of critical error messages. Always verify that logs are being written correctly to the specified facility.

9. Rotating Log Files

Configuration Option	Description	Default Value	Notes
log_rotate_interval	Interval after which log files are rotated	`1d`	Can be specified in days, hours, minutes, or seconds (e.g., `1h`, `30m`)
log_rotate_size	Maximum size of log file before rotation	`10MB`	When log file exceeds this size, it is rotated
log_rotate_count	Number of rotated log files to keep	`5`	Older logs are deleted once this limit is reached

Example: Configuring Log Rotation in rabbitmq.conf

# Rotate logs every day
log_rotate_interval = 1d

# Keep up to 5 rotated log files
log_rotate_count = 5

# Rotate when log file reaches 10MB
log_rotate_size = 10MB

Note: Log rotation is managed by the rabbitmqctl utility and requires appropriate permissions to configure.

10. Parsing Log Patterns

Log Level	Description	Typical Use Case	Example Pattern
trace	Most verbose level; includes all internal operations and debugging details.	Debugging complex issues or performance bottlenecks	`[TRACE] [connection-12345] Channel opened`
debug	Provides detailed information for developers to understand system behavior.	Development and troubleshooting	`[DEBUG] [channel-67890] Message published to queue 'myqueue'`
info	General operational messages indicating normal flow of events.	Monitoring and general system status	`[INFO] [node-abcde] Node started successfully`
warning	Indicates potential issues that do not stop operation but require attention.	System health monitoring	`[WARNING] [queue-xyz] Queue 'test' has high message rate`
error	Indicates errors that prevent a specific operation from completing.	Error tracking and alerting	`[ERROR] [broker-12345] Failed to connect to broker`
critical	Severe errors that may cause system instability or crash.	Critical incident response	`[CRITICAL] [node-abcde] Memory allocation failed`

Example: Log Pattern Matching in Configuration

log:
  level: debug
  file:
    path: "/var/log/rabbitmq/rabbit.log"
    max_size: 10MB
    max_files: 5
  pattern:
    format: "%d{yyyy-MM-dd HH:mm:ss} [%p] [%t] %m%n"
    timestamp: "yyyy-MM-dd HH:mm:ss"

Note: The log pattern format can be customized using standard logging libraries like Logback (Java) or Python's logging module.

Key Points for Log Parsing

Log levels help filter and prioritize messages based on severity.
Custom log patterns enable structured logging for easier parsing and analysis.
Timestamp formats should be consistent across logs to support automated parsing tools.

11. Integrating with Log Aggregators

Example: Configuring RabbitMQ to Send Logs to a Centralized Service

# Enable logging to a remote syslog server
rabbitmqctl set_vm_memory_high_watermark 0.4
rabbitmqctl set_log_level info

# Configure logging to a file for external parsing
echo 'log.dir = /var/log/rabbitmq' >> /etc/rabbitmq/rabbitmq.conf
echo 'log.file = rabbitmq.log' >> /etc/rabbitmq/rabbitmq.conf

Configuration Option	Description	Default Value	Notes
log.dir	Directory where log files are stored	`/var/log/rabbitmq`	Must be writable by RabbitMQ user
log.file	Name of the main log file	`rabbitmq.log`	Can be overridden to support log rotation
log.syslog	Enable logging to syslog	`false`	Set to `true` to send logs to system log
log.syslog_facility	Syslog facility to use	`local0`	Valid values: `auth`, `local0`-`local7`

Comparison: Log Aggregator Integration Options

Syslog Integration: Sends logs to system log daemon (e.g., rsyslog), which can forward to centralized services like ELK stack or Splunk
File-based Logging: Writes logs to disk, suitable for ingestion by tools like Fluentd or Logstash
External Logging Frameworks: Use libraries like Logback or Log4j for more advanced formatting and routing

Note: Ensure that the log directory and file permissions are correctly set to allow RabbitMQ to write logs without errors.

12. Troubleshooting via Logs

Log Level	Description	Use Case
debug	Most verbose level, includes detailed internal operations and state changes.	Development and deep diagnostics
info	General operational messages, including startup and shutdown events.	Production monitoring and general tracking
warning	Non-fatal issues that may require attention but don't stop operations.	Identifying potential problems before they escalate
error	Fatal errors that prevent normal operation or cause data loss.	Immediate incident response and root cause analysis

Example: Setting Log Level in rabbitmq.conf

# Set the log level to debug for troubleshooting
log.level = debug

# Enable detailed logging for specific modules
log.module.amqp = debug
log.module.mnesia = info

Note: Log levels can be adjusted dynamically without restarting the broker, but changes may not take effect immediately depending on the logging backend.

Common Log Analysis Patterns

Error messages often indicate failed operations or configuration issues.
Warning messages can signal deprecated features or performance bottlenecks.
Debug logs are useful for tracing message flow and internal state changes.

Log File vs Console Output

File-based logs provide persistent storage for long-term analysis and debugging.
Console output is useful for real-time monitoring and development environments.