tarantool / config

App configuration library

Tarantool app configurator

This module allows you to configure your Tarantool apps from configuration files, command line arguments and environment variables.

It gives you the ability to mix and match different ways of configuration, so your app can work unmodified during local development, as a systemd service, or as part of Docker image.

Example usage

Create a file called app.lua with the following content:

#!/usr/bin/env tarantool

local config = require('config')
local yaml = require('yaml')

local cfg = config.parse({app_name="myapp", instance_name=nil})


print(cfg.some_option)
print(cfg.some_other_option)

Then you can pass some_option like this:

tarantool app.lua --some_option foobar

or via environment variable:

TARANTOOL_SOME_OPTION=foobar tarantool app.lua

or by placing the following configuration file to $HOME/.config/tarantool/tarantool.ini:

[default]

some_option = foobar

Alternatively, you can use yml format as well $HOME/.config/tarantool/tarantool.yml:

---

default:
  some_option: foobar

How it works

The config module tries to read configuration options from multiple sources and then merge them together according to the priority of the source. Configuration files have lowest priority, then command line options, then environment variables.

Configuration files have an ini or yaml format and have multiple sections that allow to specify settings for all tarantool apps, specific tarantool app or a specific instance of tarantool app.

default section of configuration file has global configuration, then if there is a section called myapp, values from there will override values from default, and then myapp.instance_name with highest priority.

So the complete order looks like this:

• check TARANTOOL_<VARNAME> environment variable
• check --<varname> command line option
• check <varname>= in [myapp.instance_name] section of config file
• check <varname>= in [myapp] section of config file
• check <varname>= in [default] section of config file

All configuration values are treated as regular strings. It's your job to convert them to other types.