MENU.LUA(8)

NAME
menu.lua - bootloader dynamic menu module

DESCRIPTION
menu.lua contains the main functionality required to build a dynamic menu system. It also contains definitions for the built-in menus, some of which are influenced by loader(8) environment variables.

Before hooking into the functionality provided by menu.lua, it must be included with a statement such as the following:

    local menu = require("menu")

  MENU DEFINITIONS
Menus are represented in menu.lua as a table. That table must contain an entries key.

If the value of the entries key is itself a table, then each value in this table defines a single entry in this menu. See MENU ITEM DEFINITIONS for the structure of each entry.

entries may also be a function. This function must return a table, each value of which defines a single entry in this menu. See MENU ITEM DEFINITIONS.

  MENU ITEM DEFINITIONS
The following keys may be defined for a menu item:

entry_type
    The type of this menu entry. See MENU ITEM TYPES.

carousel_id
    A unique string id for this carousel. A carousel is a menu entry that rotates through a selection of items. Used for storage of the carousel's current setting.

visible
    A lambda that returns true if this menu item should be visible and false if it should not be visible.

items
    A table (or a lambda that returns a table) of the possible choices for this carousel.

name
    A string (or a lambda that returns a string) containing the current name of this item.

func
    The function executed when this entry is selected. Every type except for core.MENU_SEPARATOR may have a func.

submenu
    The submenu menu definition to draw when this entry is selected.

alias
    A table of case-sensitive aliases for this menu entry. All menu entries that can be selected may have any number of alias entries.

entry_type is the only required key for every entry type. name is required for all entry types except for core.MENU_SEPARATOR.

  MENU ITEM TYPES
The menu item type constants are defined in core.lua(8). The following types are available:

core.MENU_RETURN
    Return to the parent menu. If the current menu is the default menu, menu.lua will exit the menu and begin the autoboot sequence (if applicable). This type of menu entry may execute func, when selected, and has a name.

core.MENU_ENTRY
    A normal menu entry that executes func when selected, and has a name.

core.MENU_SEPARATOR
    A menu entry that serves as a separator. It may have a name.

core.MENU_SUBMENU
    A menu entry that opens submenu when selected. It may have a name.

core.MENU_CAROUSEL_ENTRY
    A menu entry that rotates through items like a carousel. func is executed when selected, and the callback is passed the choice index, name of the current choice, and the table of choices.

  EXPORTED MENUS
The following menus are exported by menu.lua:

menu.default
    The default menu to draw. Set to menu.welcome by default.

menu.welcome
    The welcome menu. Contains single and multi user boot options, as well as entries to access other menus.

menu.boot_options
    The "Boot Options" menu.

menu.boot_environments
    The "Boot Environments" menu. This menu is only visible if the system is booted on a ZFS partition and more than one boot environment was detected at boot.

EXAMPLES
To replace the default boot menu with a simple boot menu:

    local core = require("core")
    local menu = require("menu")
    menu.default = {
    	entries = {
    		{
    			entry_type = core.MENU_ENTRY,
    			name = "Boot",
    			func = core.boot,
    		},
    		{
    			entry_type = core.MENU_CAROUSEL_ENTRY,
    			carousel_id = "unique_boot_entry_name",
    			items = {"NO", "YES"},
    			name = function(_, choice, _)
    				return "Option: " .. choice
    			end,
    			func = function(_, _, _)
    				loader.setenv("some_envvar", "some_value")
    			end,
    		},
    	},
    }

To add another option to the welcome menu:

    local core = require("core")
    local menu = require("menu")
    local my_entry = {
    	entry_type = core.MENU_ENTRY,
    	name = "Fancy Boot",
    	func = core.boot,
    },
    local stock_entries = menu.welcome.entries
    function menu.welcome.entries()
    	local ents = stock_entries()
    	ents[#ents + 1] = my_entry
    	return ents
    end

To create a vendor submenu or other vendor menu option, override menu.welcome.all_entires.vendor like so:

    local core = require("core")
    local menu = require("menu")
    -- Fill in with vendor specific entries
    local vendor_options = {
    	entries = {
    	...
    	},
    }
    local welcome_entries = menu.welcome.all_entries
    welcome_entries.vendor = {
            entry_type = core.MENU_SUBMENU,
            name = color.highlight("V") .. "endor Options",
            submenu = vendor_options,
            alias = {"v", "V"},
    	visible = function()
    		return true
    	end,
    }

In the above example, vendor_options is a local variable that defines the vendor submenu.

To add an additional option, change the menu.boot_options.entries array. The following illustrates this concept:

    -- This is a silly example that rotates local_option through the values
    -- 0 to 4.  local_option would still need to be used elsewhere.
    local local_option = 0
    -- The `entries` of a menu may either be a table or a function.  In this
    -- example we're augmenting a menu that just has a static table, but if we
    -- wanted to be more robust then we would need to instead check the type
    -- of `stock_options` here to determine our next move.
    --
    -- If `entries` is a table, then the stock menu system won't be changing it
    -- so we can just add our menu option as we do below.
    --
    -- If `entries` is a function, then we would need to provide a new function to
    -- replace `entries` that does a core.deepCopyTable() of the result and adds
    -- the below item to it.  The deep copy is necessary to avoid duplicating our
    -- new menu item and allowing the menu to alter its behavior however it pleases.
    local stock_options = menu.boot_options.entries
    stock_options[#stock_options + 1] = {
    	entry_type = core.MENU_ENTRY,
    	name = function()
    		return color.highlight('L') ..
    		    "ocal Option     : " .. local_option
    	end,
    	func = function()
    		local_option = (local_option + 1) % 5
    	end,
    	alias= {"l", "L"}
    }

SEE ALSO
loader.conf(5), core.lua(8), loader(8)

HISTORY
The menu.lua file first appeared in FreeBSD 12.0.

AUTHORS
The menu.lua file was originally written by Pedro Souza <pedrosouza@FreeBSD.org>. Later work and this manual page was done by Kyle Evans <kevans@FreeBSD.org>.