gluon-core: create interfaces for each "port" in /etc/config/gluon

This commit enables (migration-safe) role assignment for individual "lan"
and "wan" interfaces. This is helpful especially on devices with multiple
"lan" or "wan" interfaces (as they appear for devices with DSA support).

For interfaces in /lib/gluon/lan_ifname, we now create individual
entries in /etc/config/gluon using the "/lan[0]", "/lan[1]", ...
syntax (introduced in the last commit). Before this commit, all interfaces
were referenced in a single interface "/lan" in /etc/config/gluon.

The same is done for wan_ifname and single_ifname.

Migration strategy:

If new interfaces show up during gluon-reconfigure, the assigned roles
of prior existing interfaces in the same category will be applied to the
new interface.

package/gluon-core/luasrc/lib/gluon/upgrade/021-interface-roles

@@ -52,14 +52,35 @@ local interfaces = {
 	single = sysconfig.single_ifname,
 }
 
-for iface in pairs(interfaces) do
+for iface, ifnames in pairs(interfaces) do
-	local section_name = 'iface_' .. iface
+	local default_roles = roles[iface]
-	if not uci:get('gluon', section_name) then
+
-		uci:section('gluon', 'interface', section_name, {
+	-- migration from intermediate gluon master
-			-- / prefix refers to sysconfig ifnames
+	local section_name_old = 'iface_' .. iface
-			name = '/' .. iface,
+	if uci:get('gluon', section_name_old) then
-			role = roles[iface],
+		default_roles = uci:get('gluon', section_name_old, 'role')
-		})
+		uci:delete('gluon', section_name_old)
+	end
+
+	local interface_count = 1
+	if type(ifnames) == 'table' then
+		interface_count = #ifnames
+	end
+
+	for i = 0, interface_count-1 do
+		local section_name = 'iface_' .. iface .. '_' .. tostring(i)
+
+		if not uci:get('gluon', section_name) then
+			uci:section('gluon', 'interface', section_name, {
+				-- / prefix refers to sysconfig ifnames
+				name = '/' .. iface .. '[' .. tostring(i) .. ']',
+				role = default_roles,
+			})
+		else
+			-- In case we have existing interfaces in that category, we want to
+			-- use their roles as default for other new interfaces in that category.
+			default_roles = uci:get('gluon', section_name, 'role')
+		end
 	end
 end