clio/docs/logging.md

Logging

Clio provides several logging options, which all are configurable via the config file. These are detailed in the following sections.

log_level

The minimum level of severity at which the log message will be outputted by default. Severity options are trace, debug, info, warning, error, fatal. Defaults to info.

spdlog_format

The format of log lines produced by Clio using spdlog format patterns. Defaults to "%Y-%m-%d %H:%M:%S.%f %^%3!l:%n%$ - %v".

Each of the variables expands like so:

• %Y-%m-%d %H:%M:%S.%f: The full date and time of the log entry with microsecond precision
• %^: Start color range
• %3!l: The severity (aka log level) the entry was sent at stripped to 3 characters
• %n: The logger name (channel) that this log entry was sent to
• %$: End color range
• %v: The actual log message

Some additional variables that might be useful:

• %@: A partial path to the C++ file and the line number in the said file (src/file/path:linenumber)
• %t: The ID of the thread the log entry is written from

For more information about spdlog format patterns, see: https://github.com/gabime/spdlog/wiki/Custom-formatting

spdlog_async

Whether spdlog is asynchronous or not.

log_channels

An array of JSON objects, each overriding properties for a logging channel.

Important

At the time of writing, only log_level can be overridden using this mechanism.

Each object is of this format:

{
  "channel": "Backend",
  "log_level": "fatal"
}

If no override is present for a given channel, that channel will log at the severity specified by the global log_level.

The log channels that can be overridden are: Backend, WebServer, Subscriptions, RPC, ETL and Performance.

Note

See example-config.json for more details.

log_to_console

Enable or disable log output to console. Options are true/false. This option defaults to true.

log_directory

Path to the directory where log files are stored. If such directory doesn't exist, Clio will create it.

If the option is not specified, the logs are not written to a file.

log_rotation_size

The max size of the log file in megabytes before it will rotate into a smaller file. Defaults to 2GB.

log_directory_max_files

The max number of log files in the directory before old log files will be deleted to free up space. Defaults to 25.

log_tag_style

Tag implementation to use. Must be one of:

• uint: Lock free and threadsafe but outputs just a simple unsigned integer
• uuid: Threadsafe and outputs a UUID tag
• none: Doesn't use tagging at all