Sending Commands to Devices

Default command options

By default, there are three options in the Send Command dropdown:

1. Reboot

2. Change Password

3. Custom Command

While the first two options are self-explanatory, the custom command option allows you to execute any command on the device as shown in the example below.

Note: in order for this feature to work, a device needs to have at least one Access Credential (see How to Configure Push Updates).

The Send Command button will be hidden until the device has at least one Access Credential.

If you need to allow your users to quickly send specific commands that are used often in your network regardless of your users’ knowledge of Linux shell commands, you can add new commands by following instructions in “How to define new options in the commands menu” section below.

If you are an advanced user and want to register commands programatically, then refer to “Register / Unregistering commands” section.

How to define new options in the commands menu

It is possible to define new custom commands which are added to the menu of available commands, this allows to make it easy for users perform additional management actions without having to be Linux/Unix experts and know the exact shell command syntax (because the system generates the command for them based on the input received via the UI).

We can do so by using the OPENWISP_CONTROLLER_USER_COMMANDS django setting (see How to Edit Django Settings).

The following example defines a simple command that can ping an input destination_address through a network interface, interface_name.

# In yourproject/settings.py

def ping_command_callable(destination_address, interface_name=None):
    command = f'ping -c 4 {destination_address}'
    if interface_name:
        command += f' -I {interface_name}'
    return command

OPENWISP_CONTROLLER_USER_COMMANDS = [
    (
        'ping',
        {
            'label': 'Ping',
            'schema': {
                'title': 'Ping',
                'type': 'object',
                'required': ['destination_address'],
                'properties': {
                    'destination_address': {
                        'type': 'string',
                        'title': 'Destination Address',
                    },
                    'interface_name': {
                        'type': 'string',
                        'title': 'Interface Name',
                    },
                },
                'message': 'Destination Address cannot be empty',
                'additionalProperties': False,
            },
            'callable': ping_command_callable,
        }
    )
]

The above code will add the “Ping” command in the user interface as show in the GIF below:

The OPENWISP_CONTROLLER_USER_COMMANDS setting takes a list of tuple each containing two elements. The first element of the tuple should contain an identifier for the command and the second element should contain a dict defining configuration of the command.

Command Configuration

The dict defining configuration for command should contain following keys:

1. label

A str defining label for the command used internally by Django.

2. schema

A dict defining JSONSchema for inputs of command. You can specify the inputs for your command, add rules for performing validation and make inputs required or optional.

Here is a detailed explanation of the schema used in above example:

{
    # Name of the command displayed in "Send Command" widget
    'title': 'Ping',
    # Use type "object" if the command needs to accept inputs
    # Use type "null" if the command does not accepts any input
    'type': 'object',
    # Specify list of inputs that are required
    'required': ['destination_address'],
    # Define the inputs for the commands along with their properties
    'properties': {
        'destination_address': {
            # type of the input value
            'type': 'string',
            # label used for displaying this input field
            'title': 'Destination Address',
        },
        'interface_name': {
            'type': 'string',
            'title': 'Interface Name',
        },
    },
    # Error message to be shown if validation fails
    'message': 'Destination Address cannot be empty'),
    # Whether specifying addtionaly inputs is allowed from the input form
    'additionalProperties': False,
}

This example uses only handful of properties available in JSONSchema. You can experiment with other properties of JSONSchema for schema of your command.

3. callable

A callable or str defining dotted path to a callable. It should return the command (str) to be executed on the device. Inputs of the command are passed as arguments to this callable.

The example above includes a callable(ping_command_callable) for ping command.