Managing modules

Installing a module from a repository

See README in tarantool/rocks repository for detailed instructions.

Installing a module from deb/rpm

Follow these steps:

1. Install Tarantool as recommended on the download page.

2. Install the module you need. Look up the module’s name on Tarantool rocks page and put the prefix “tarantool-” before the module name to avoid ambiguity:

   $ # for Ubuntu/Debian:
   $ sudo apt-get install tarantool-<module-name>
   
   $ # for RHEL/CentOS/Amazon:
   $ sudo yum install tarantool-<module-name>
   

   For example, to install the module vshard on Ubuntu, say:

   $ sudo apt-get install tarantool-vshard
   

Once these steps are complete, you can:

• load any module with

  tarantool> name = require('module-name')
  

  for example:

  tarantool> vshard = require('vshard')
  

• search locally for installed modules using package.path (Lua) or package.cpath (C):

  tarantool> package.path
  ---
  - ./?.lua;./?/init.lua; /usr/local/share/tarantool/?.lua;/usr/local/share/
  tarantool/?/init.lua;/usr/share/tarantool/?.lua;/usr/share/tarantool/?/ini
  t.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/
  usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;
  ...
  
  tarantool> package.cpath
  ---
  - ./?.so;/usr/local/lib/x86_64-linux-gnu/tarantool/?.so;/usr/lib/x86_64-li
  nux-gnu/tarantool/?.so;/usr/local/lib/tarantool/?.so;/usr/local/lib/x86_64
  -linux-gnu/lua/5.1/?.so;/usr/lib/x86_64-linux-gnu/lua/5.1/?.so;/usr/local/
  lib/lua/5.1/?.so;
  ...
  

  Note

  Question-marks stand for the module name that was specified earlier when saying require('module-name').

Reloading a module in Lua

Here’s an example that illustrates the most typical case – “update and reload”.

1. Update the application file.

   For example, a module in /usr/share/tarantool/app.lua:

   local function start()
     -- initial version
     box.once("myapp:v1.0", function()
       box.schema.space.create("somedata")
       box.space.somedata:create_index("primary")
       ...
     end)
   
     -- migration code from 1.0 to 1.1
     box.once("myapp:v1.1", function()
       box.space.somedata.index.primary:alter(...)
       ...
     end)
   
     -- migration code from 1.1 to 1.2
     box.once("myapp:v1.2", function()
       box.space.somedata.index.primary:alter(...)
       box.space.somedata:insert(...)
       ...
     end)
   end
   
   -- start some background fibers if you need
   
   local function stop()
     -- stop all background fibers and clean up resources
   end
   
   local function api_for_call(xxx)
     -- do some business
   end
   
   return {
     start = start,
     stop = stop,
     api_for_call = api_for_call
   }
   

2. Update the instance file.

   For example, /etc/tarantool/instances.enabled/my_app.lua:

   #!/usr/bin/env tarantool
   --
   -- hot code reload example
   --
   
   box.cfg({listen = 3302})
   
   -- ATTENTION: unload it all properly!
   local app = package.loaded['app']
   if app ~= nil then
     -- stop the old application version
     app.stop()
     -- unload the application
     package.loaded['app'] = nil
     -- unload all dependencies
     package.loaded['somedep'] = nil
   end
   
   -- load the application
   log.info('require app')
   app = require('app')
   
   -- start the application
   app.start({some app options controlled by sysadmins})
   

   The important thing here is to properly unload the application and its dependencies.

3. Manually reload the application file.

   For example, using tt:

   $ tt connect my_app -f /etc/tarantool/instances.enabled/my_app.lua
   

Reloading a module in C

After you compiled a new version of a C module (*.so shared library), call box.schema.func.reload(‘module-name’) from your Lua script to reload the module.