1 files changed, 56 insertions, 0 deletions
diff --git a/modules/etcd/etcd.lua b/modules/etcd/etcd.lua
new file mode 100644
index 0000000..ab58024
--- /dev/null
+++ b/modules/etcd/etcd.lua
@@ -0,0 +1,56 @@
+--- @module etcd
+-- SPDX-License-Identifier: GPL-3.0-or-later
+local etcd = {}
+
+-- @function update subtree configuration
+local function update_subtree(tree)
+	if not tree then return end
+	for _, k in pairs(tree) do
+		if k.dir then
+			update_subtree(k.nodes)
+		else
+			local key,opt = k.key:gmatch('([^/]+)/([^/]+)$')()
+			if _G[key][opt] ~= k.value then
+				_G[key][opt] = k.value
+			end
+		end
+	end
+end
+
+-- @function reload whole configuration
+function etcd.reload()
+	local res, err = etcd.cli:readdir('/', true)
+	if err then
+		error(err)
+	end
+	update_subtree(res.body.node.nodes)
+end
+
+function etcd.init()
+	etcd.Etcd = require('etcd.luasocket')
+	etcd.defaults = { prefix = '/knot-resolver' }
+end
+
+function etcd.deinit()
+	if etcd.ev then event.cancel(etcd.ev) end
+end
+
+function etcd.config(conf)
+	local options = etcd.defaults
+	if type(conf) == 'table' then
+		for k,v in pairs(conf) do options[k] = v end
+	end
+	-- create connection
+	local cli, err = etcd.Etcd.new(options)
+	if err then
+		error(err)
+	end
+	etcd.cli = cli
+	-- schedule recurrent polling
+	-- @todo: the etcd has watch() API, but this requires
+	--        coroutines on socket operations
+	if etcd.ev then event.cancel(etcd.ev) end
+	etcd.ev = event.recurrent(5 * sec, etcd.reload)
+end
+
+return etcd