Sample maintenance work file prepared for Lua supported Nginx. You can customize it as you like.

maintenance.lua

-- Sample maintenance work file prepared for Lua supported Nginx. You can customize it as you like.

-- Note: It works within websites that work with 
-- services such as Reverse proxy and CloudFlare, 
-- and you can create a special article or html 
-- page by changing ngx.exit(ngx.HTTP_FORBIDDEN)

local whitelist = {
    "192.168.1.2",
    "192.168.1.3",
}

local remote_addr = ""
if ngx.var.http_cf_connecting_ip ~= nil then
    remote_addr = ngx.var.http_cf_connecting_ip
elseif ngx.var.http_x_forwarded_for ~= nil then
    remote_addr = ngx.var.http_x_forwarded_for
else
    remote_addr = ngx.var.remote_addr
end

local function check(ips)
    local ips_length = #ips
    for i=1,ips_length do
        local value = ips[i]
        if value == remote_addr then
        return
        end
    end
    return ngx.exit(ngx.HTTP_FORBIDDEN)
end

check(whitelist)