lua plugin system

rootfs/etc/nginx/lua/plugins.lua

@@ -0,0 +1,48 @@
+local string_format = string.format
+local new_tab = require "table.new"
+local ngx_log = ngx.log
+local INFO = ngx.INFO
+local ERR = ngx.ERR
+
+local _M = {}
+local MAX_NUMBER_OF_PLUGINS = 10000
+-- TODO: is this good for a dictionary?
+local plugins = new_tab(MAX_NUMBER_OF_PLUGINS, 0)
+
+local function load_plugin(name)
+  local path = string_format("plugins.%s.main", name)
+
+  local ok, plugin = pcall(require, path)
+  if not ok then
+    ngx_log(ERR, string_format("error loading plugin \"%s\": %s", path, plugin))
+    return
+  end
+
+  plugins[name] = plugin
+end
+
+function _M.init(names)
+  for _, name in ipairs(names) do
+    load_plugin(name)
+  end
+end
+
+function _M.run()
+  local phase = ngx.get_phase()
+
+  for name, plugin in pairs(plugins) do
+    if plugin[phase] then
+      ngx_log(INFO, string_format("running plugin \"%s\" in phase \"%s\"", name, phase))
+
+      -- TODO: consider sandboxing this, should we?
+      -- probably yes, at least prohibit plugin from accessing env vars etc
+      -- but since the plugins are going to be installed by ingress-nginx operator they can be assumed to be safe also
+      local ok, err = pcall(plugin[phase])
+      if not ok then
+        ngx_log(ERR, string_format("error while running plugin \"%s\" in phase \"%s\": %s", name, phase, err))
+      end
+    end
+  end
+end
+
+return _M