Extending the tt functionality
The tt utility implements a modular architecture: its commands
are, in fact, separate modules. When you run tt with a command, the
corresponding module is executed with the given arguments.
The modular architecture enables the option to extend the tt functionality with
external modules (as opposed to internal modules that implement built-in
commands). Simply said, you can write any code you want to execute
from tt, pack it into an executable, and run it with a tt command:
tt my-module-name my-args
The name of the command that executes a module is the same as the name of the module’s executable.
Executables that implement external tt modules must have two flags:
--description– print a short description of the module. The description is shown alongside the command in thetthelp.--help– display help. The help message is shown whentt help <module_name>is called.
External modules must be located in the modules directory specified in the configuration file:
tt: modules: directory: path/to/modules/dir
To check if a module is available in tt, call tt help.
It will show the available external modules in the EXTERNAL COMMANDS section together
with their descriptions.
External modules can overload built-in tt commands.
If you want to change the behavior of a built-in command, create an external
module with the same name and your own implementation.
When tt sees two modules – an external and an internal one – with the same
name, it will use the external module by default.
For example, if you want tt to show the information about your Tarantool
application, write the external module version that outputs the information
you need. The tt version call will execute this module instead of the built-in one:
tt version # Calls the external module if it's available
You can force the use of the internal module by running tt with the --internal or -I
option. The following call will execute the built-in version
even if there is an external module with the same name:
tt version -I # Calls the internal module