Logging Configuration

RobustMQ uses a logging system based on tracing and tracing-subscriber, supporting multiple output appenders and flexible filtering. Each appender is defined as a TOML section in the tracing configuration file.

Configuration Files

Logging involves two configuration layers:

1. config/server.toml — specifies the path to the tracing config and the log output directory:

[log]
log_config = "./config/logger.toml"
log_path = "./logs"

2. config/logger.toml — defines all log appenders (console, file, tokio-console).

---

Appender Types

Each TOML section in logger.toml defines one appender. The section name is arbitrary (e.g. [stdout], [server], [raft]). The kind field determines the appender type.

kind	Description
console	Writes to stdout
rolling_file	Writes to rotating log files
tokio_console	Enables tokio-console debugging

---

Filtering

Each appender must specify exactly one of the following filter modes:

Level filter

Applies a global log level to all modules.

level = "info"

Target filter

Filters logs from a single module path.

target = { path = "openraft", level = "info" }

Targets filter

Filters logs from multiple module paths with independent levels. Useful for including one module while excluding a sub-module.

targets = [
    { path = "openraft", level = "info" },
    { path = "openraft::engine", level = "off" },
]

Available log levels: off, error, warn, info, debug, trace

---

Console Appender

Writes log output to stdout.

[stdout]
kind = "console"
level = "info"

Parameter	Type	Required	Default	Description
kind	string	yes	—	Must be "console"
level / target / targets	—	yes	—	Filter mode (choose one)
ansi	bool	no	true	Enable ANSI color output
formatter	string	no	default format	Output format: compact, pretty, json

---

Rolling File Appender

Writes logs to files with time-based rotation and automatic cleanup.

[server]
kind = "rolling_file"
level = "info"
rotation = "daily"
directory = "./data/broker/logs"
prefix = "server"
suffix = "log"
max_log_files = 50

Parameter	Type	Required	Default	Description
kind	string	yes	—	Must be "rolling_file"
level / target / targets	—	yes	—	Filter mode (choose one)
rotation	string	yes	—	Rotation strategy: minutely, hourly, daily, never
directory	string	yes	—	Log file output directory
prefix	string	no	none	Log filename prefix
suffix	string	no	none	Log filename suffix
max_log_files	number	no	unlimited	Maximum number of rotated log files to keep
ansi	bool	no	true	Enable ANSI color in file output (usually set false for files)
formatter	string	no	default format	Output format: compact, pretty, json

Log file naming: {prefix}.{date}.{suffix} — for example, with prefix = "server", suffix = "log", rotation = "daily", the file is named like server.2025-02-06.log.

---

Tokio Console Appender

Enables the tokio-console subscriber for debugging async runtime behavior.

[tokio_console]
kind = "tokio_console"
bind = "127.0.0.1:5674"
grpc_web = true

Parameter	Type	Required	Default	Description
kind	string	yes	—	Must be "tokio_console"
bind	string	no	127.0.0.1:6669	gRPC server bind address
grpc_web	bool	no	false	Enable gRPC-Web support

Note: This appender does not support level, ansi, or formatter parameters.

---

Default Configuration

The default config/logger.toml ships with the following appenders:

# Console output
[stdout]
kind = "console"
level = "info"

# Main server logs
[server]
kind = "rolling_file"
level = "info"
rotation = "daily"
directory = "./data/broker/logs"
prefix = "server"
suffix = "log"
max_log_files = 50

# HTTP API request logs
[http_request]
kind = "rolling_file"
targets = [{ path = "admin_server::server", level = "info" }]
rotation = "daily"
directory = "./data/broker/logs"
prefix = "http_request"
suffix = "log"
max_log_files = 50

# Raft consensus logs
[raft]
kind = "rolling_file"
targets = [{ path = "openraft", level = "info" }]
rotation = "daily"
directory = "./data/broker/logs"
prefix = "raft"
suffix = "log"
max_log_files = 50

# Meta service logs
[meta]
kind = "rolling_file"
targets = [{ path = "meta_service", level = "info" }]
rotation = "daily"
directory = "./data/broker/logs"
prefix = "meta"
suffix = "log"
max_log_files = 50

# Openraft logs excluding engine module
[openraft_except_engine]
kind = "rolling_file"
targets = [
    { path = "openraft", level = "info" },
    { path = "openraft::engine", level = "off" },
]
rotation = "daily"
directory = "./data/broker/logs"
prefix = "openraft-except-engine"
suffix = "log"
max_log_files = 10

---

Preset Examples

Development Environment

[stdout]
kind = "console"
level = "debug"
formatter = "pretty"

[server]
kind = "rolling_file"
level = "debug"
rotation = "hourly"
directory = "./logs"
prefix = "dev"
suffix = "log"
max_log_files = 10

Production Environment

[stdout]
kind = "console"
level = "info"
formatter = "compact"

[server]
kind = "rolling_file"
level = "info"
rotation = "daily"
directory = "/var/log/robustmq"
prefix = "server"
suffix = "log"
max_log_files = 30

[error]
kind = "rolling_file"
level = "error"
rotation = "daily"
directory = "/var/log/robustmq"
prefix = "error"
suffix = "log"
max_log_files = 90