InitLoggingByFormat initalializes a logger with specified format and outputs a startup message.

InitLoggingByFormatSilent initializes a logger with specified format without outputting a startup message.

InitLoggingFromEnv initializes a logger with the format specified in the environment variable and outputs a startup message.

SetLoggingLevelFromEnv sets the logging level from which log messages and higher are outputted via envvar ESTAFETTE_LOG_LEVEL.

LogFormatConsole outputs logs in plain text with colorization and without timestamp.

LogFormatJSON outputs logs in json including appgroup, app, appversion and other metadata.

LogFormatPlainText outputs logs in plain text without colorization and with timestamp; is the default if log format isn't specified.

LogFormatStackdriver outputs a format similar to JSON format but with 'severity' instead of 'level' field.