src/backend/doc/log_config.md

Backend - Configuring Logs

Log visibility specified by configuration file

The configuration file can define an array parameter called logging. This configures the visibility of specific logs in core areas based on which string flags are present.

For example, the following configuration will cause FileCacheService to log information about cache hits and misses:

{
    "logging": ['file-cache']
}

Sometimes "enabling" a log means moving its log level from debug to info.

Available logging flags:

• file-cache: file cache hits and misses
• http: http requests
• fsentries-not-found: information about files that were stat'd but weren't there

Other log options

• Setting log_upcoming_alarms to true will log alarms before they are created. This would be useful if AlarmService itself is failing.
• Setting trace_logs to true will display a stack trace below every log message. This can be useful if you don't know where a particular log is coming from and want to track it down.

Service-level log configuration

Services can be configured to change their logging behavior. Services will have one of two behaviors:

1. info logging - log.info can be used to create an [INFO] log message
2. debug logging only - log.info is redirected to log.debug

Services will have info logging enabled by default, unless the class definition has the static member static LOG_DEBUG = true (in which case debug logging only is the default).

In a service's configuration block the desired behavior can be specified by setting either "log_debug": true or "log_info": true