monolog: channels: - deprecation handlers: file_log: type: rotating_file path: "%kernel.logs_dir%/%kernel.environment%.log" level: error when@dev: monolog: handlers: main: type: stream path: '%kernel.logs_dir%/dev.log' level: debug channels: ['!event'] deprecation: type: stream path: '%kernel.logs_dir%/deprecations.log' level: info channels: [deprecation] stdout: type: stream path: php://stdout level: debug channels: ['!event'] when@prod: monolog: handlers: file: type: rotating_file path: "%kernel.logs_dir%/%kernel.environment%.log" level: info channels: ['!event'] formatter: monolog.formatter.line deprecation: type: rotating_file path: '%kernel.logs_dir%/deprecations.log' level: warning channels: [deprecation]