Original article available at https://habrahabr.ru/company/mailru/blog/334266/ Hi there! In this article, I’d like to share my experience creating applications for 1.7. It’s the first in a series of tutorials that might be useful both to those who’ve already decided to give Tarantool a try and to those who are still looking for a solution to streamline their projects. Tarantool The whole series will cover an existing Tarantool application, and this tutorial will touch upon such topics as installing Tarantool, storing and accessing data, and writing efficient stored procedures. Tarantool is a NoSQL database that stores data in RAM or on disk (depending on the storage engine) and ensures persistence via a well-thought-out mechanism called a write-ahead log (WAL). Tarantool boasts a built-in LuaJIT (just-in-time) compiler that allows executing Lua code. You can also create stored procedures in C. Why write your own Tarantool applications There are two main reasons: This speeds up your service. Storage-side data processing reduces data traffic, and bundling several requests into a stored procedure helps minimize network latency. Ready applications can be reused. Tarantool ecosystem is actively evolving, with people creating more and more open-source Tarantool applications. With time, some of them become part of Tarantool itself. Such packages shorten time for new services. development Naturally enough, this approach has its downside. Tarantool can’t take full advantage of a multi-core CPU, so if you strive to make your service scalable, you’ll need to shard your database and design an appropriate project architecture. On the bright side, as the number of requests grows, the workload becomes easy to scale. Now I’m going to walk you through the creation of a Tarantool application that implements an API for registering and authenticating users. It offers the following capabilities: registration and authentication via email in two steps: creating an account and confirming the registration and setting the password; registration with social network credentials (FB, VK, Google+); password recovery. For an example of a stored procedure for Tarantool, we’ll take a look at the first step of email registration — getting a confirmation code. To make it more interactive, you can check this and follow along. GitHub page Let’s go! Installing Tarantool You can find detailed installation instructions for different operating systems . For example, to install Tarantool on Ubuntu, you’ll need to run the following commands in the console: on this site curl | sudo apt-key add -release=`lsb_release -c -s` http://download.tarantool.org/tarantool/1.7/gpgkey sudo apt-get -y install apt-transport-https sudo rm -f /etc/apt/sources.list.d/*tarantool*.listsudo tee /etc/apt/sources.list.d/tarantool_1_7.list <<- EOFdeb $release maindeb-src $release mainEOF http://download.tarantool.org/tarantool/1.7/ubuntu/ http://download.tarantool.org/tarantool/1.7/ubuntu/ sudo apt-get updatesudo apt-get -y install tarantool Let’s check the installation has been successful by typing and entering the interactive administrator console. tarantool $ tarantoolversion 1.7.3–202-gfe0a67ctype ‘help’ for interactive helptarantool> This is where you can try your hand at Lua programming. If you’re not too familiar with Lua, here’s a to get you started. short tutorial Registration via email It’s time to take it one step further and write our first script that creates a space that will be holding all the users. A space is analogous to a data storage table. Data itself is stored in tuples (arrays holding records). Each space must have one primary index and can have several secondary ones. Indexes can be defined on a single or multiple fields. Below is a space scheme for our authentication service: As you can see from the image, we’re using indexes of two types: HASH and TREE. A HASH index allows finding tuples by a fully matching primary key and must be unique. A TREE index supports non-unique keys, enables searches by the first part of a composite index, and lets us streamline key sorting, since key values within an index are ordered. The space holds a special key ( ) used for signing session cookies. Storing session keys allows logging users out on the service side, if necessary. A session also has an optional link to the space. It’s necessary for validating the sessions of those users who log in with social network credentials (we’re checking the validity of the stored OAuth2 token). session session_secret social Before we start writing the application itself, it’s worth taking a look at the structure of the project: tarantool-authman├── authman│ ├── model│ │ ├── password.lua│ │ ├── password_token.lua│ │ ├── session.lua│ │ ├── social.lua│ │ └── user.lua│ ├── utils│ │ ├── http.lua│ │ └── utils.lua│ ├── db.lua│ ├── error.lua│ ├── init.lua│ ├── response.lua│ └── validator.lua└── test├── case│ ├── auth.lua│ └── registration.lua├── authman.test.lua└── config.lua Paths specified in the variable are used for importing Lua packages. In our case, packages are imported relatively to the current directory, that is . However, if necessary, import paths can easily be extended as follows: package.path tarantool-authman package.path = “/some/other/path/?.lua;” .. package.path -- Prepending a new path with the highest priority Before creating the first space, let’s put all the needed constants into separate models. We need to give each space and each index a name. It’s also necessary to specify the order of fields in a tuple. For example, here’s what the model looks like: authman/model/user.lua local user = {} -- Our package is a Lua table function user.model(config)local model = {} -- The package has the only function — model — that returns a table-- with the model’s fields and methods -- The function receives configurations in the form of a Lua table model.SPACE_NAME = ‘auth_user’model.PRIMARY_INDEX = ‘primary’model.EMAIL_INDEX = ‘email_index’ -- Space and index names -- model.ID = 1model.EMAIL = 2model.TYPE = 3model.IS_ACTIVE = 4 -- Assigning numbers to tuple fields Lua uses one-based (!) indexing model.COMMON_TYPE = 1model.SOCIAL_TYPE = 2 -- User types: registered via email or with social network-- credentials return modelend return user -- Returning the package When handling users, we’ll need two indexes: unique by id and non-unique by email address — when two different users register with social network credentials, they may be assigned the same email address, or even no email address at all. As for the users who registered the regular way, our application will make sure their email addresses are unique. The package contains a method for creating spaces: authman/db.lua local db = {} local user = require(‘authman.model.user’).model() -- Importing the package and calling the model function -- The config parameter is assigned a nil (empty) value function db.create_database() -- The db package’s method for creating spaces and indexes local user_space = box.schema.space.create(user.SPACE_NAME, {if_not_exists = true})user_space:create_index(user.PRIMARY_INDEX, {type = ‘hash’,parts = {user.ID, ‘string’},if_not_exists = true})user_space:create_index(user.EMAIL_INDEX, {type = ‘tree’,unique = false,parts = {user.EMAIL, ‘string’, user.TYPE, ‘unsigned’},if_not_exists = true})end return db UUID will serve as a user id, and we’ll be using a HASH index for full-match searches. The index for searches by email will be two-part: — user’s email address, — user type. As a reminder, the types have been defined in the model a bit earlier. A composite index enables searches not only by all the fields, but also by the first part of the index; therefore, we can search by email address only (without the user type). (user.EMAIL, ‘string’) (user.TYPE, ‘unsigned’) Let’s enter the interactive administrator console and try to use the package. authman/db.lua $ tarantoolversion 1.7.3–202-gfe0a67ctype ‘help’ for interactive helptarantool> db = require(‘authman.db’)tarantool> box.cfg({listen=3331})tarantool> db.create_database() Great, we’ve just created the first space! One thing to keep in mind here: before calling , you need to configure and run the server via the method. Now we can perform some simple actions within the space we created: box.schema.space.create box.cfg -- Creating userstarantool> box.space.auth_user:insert({‘user_id_1’, ‘exaple_1@mail.ru’, 1})— -- [ , , 1]…tarantool> box.space.auth_user:insert({‘user_id_2’, ‘exaple_2@mail.ru’, 1})— -- [ , , 1]…-- Getting a Lua table (array) with all the userstarantool> box.space.auth_user:select()— -- — [ , , 1]— [‘user_id_1’, ‘exaple_1@mail.ru’, 1]… ‘user_id_1’ ‘exaple_1@mail.ru’ ‘user_id_2’ ‘exaple_2@mail.ru’ ‘user_id_2’ ‘exaple_2@mail.ru’ -- Getting a user by the primary keytarantool> box.space.auth_user:get({‘user_id_1’})— -- [ , , 1]… ‘user_id_1’ ‘exaple_1@mail.ru’ -- Getting a user by the composite keytarantool> box.space.auth_user.index.email_index:select({‘exaple_2@mail.ru’, 1})— -- — [ , , 1]… ‘user_id_2’ ‘exaple_2@mail.ru’ -- Changing the data in the second fieldtarantool> box.space.auth_user:update(‘user_id_1’, {{‘=’, 2, ‘new_email@mail.ru’}, })— -- [ , , 1]… ‘user_id_1’ ‘new_email@mail.ru’ Unique indexes restrict the insertion of non-unique values. If you need to create some records that may already be in a space, use the (update/insert) operation. You can find the full list of available methods . upsert in the official documentation Let’s extend the user model with a capability to register users: function model.get_space()return box.space[model.SPACE_NAME]end function model.get_by_email(email, type)if validator.not_empty_string(email) thenreturn model.get_space().index[model.EMAIL_INDEX]:select({email, type})[1]endend -- function model.create(user_tuple)local user_id = uuid.str()local email = validator.string(user_tuple[model.EMAIL]) anduser_tuple[model.EMAIL] or ‘’return model.get_space():insert{user_id,email,user_tuple[model.TYPE],user_tuple[model.IS_ACTIVE],user_tuple[model.PROFILE]}end -- Creating a user Fields that are not part of the unique index are not mandatory -- -- function model.generate_activation_code(user_id)return digest.md5_hex(string.format(‘%s.%s’,config.activation_secret, user_id))end -- Generating a confirmation code sent via email and used for-- account activation Usually, this code is embedded into a link as a GET parameter activation_secret — one of the configurable parameters when-- initializing the application The code snippet below uses two standard Tarantool packages — and — and one user-created package — . Before you can use them, they need to be imported: uuid digest validator local digest = require(‘digest’)local uuid = require(‘uuid’) local validator = require(‘authman.validator’) -- Standard Tarantool packages -- Our application’s package (handles data validation) When declaring variables, we’re using the operator that limits their scope to the current block. Otherwise, these variables will be global, which is what we need to avoid due to potential name collisions. local Now let’s create the main package — — that will hold all the API methods: authman/init.lua local auth = {} local response = require(‘authman.response’)local error = require(‘authman.error’)local validator = require(‘authman.validator’)local db = require(‘authman.db’)local utils = require(‘authman.utils.utils’) function auth.api(config)local api = {}-- -- config = validator.config(config) -- The package returns the only function — api — that configures and-- returns the application The validator package contains checks for various value types This package sets the default values as well local user = require(‘authman.model.user’).model(config) -- Importing the models for working with data db.create_database() -- Creating a space function api.registration(email)-- email = utils.lower(email) -- The api method creates a non-active user with a specified email-- address Preprocessing the email address — making it all lowercase if not validator.email(email) then  
  return response.error(error.INVALID\_PARAMS)  
end

_-- Checking if there already exists a user with a given email  
-- address_  
local user\_tuple = user.get\_by\_email(email, user.COMMON\_TYPE)  
if user\_tuple ~= nil then  
  if user\_tuple\[user.IS\_ACTIVE\] then  
    return response.error(error.USER\_ALREADY\_EXISTS)  
  else  
    local code = user.generate\_activation\_code(user\_tuple\[user.ID\])  
    return response.ok(code)  
  end  
end

_-- Writing data to the space_  
user\_tuple = user.create({  
  \[user.EMAIL\] = email,  
  \[user.TYPE\] = user.COMMON\_TYPE,  
  \[user.IS\_ACTIVE\] = false,  
})

local code = user.generate\_activation\_code(user\_tuple\[user.ID\])  
return response.ok(code) end return apiend return auth Great! Now users can create accounts. tarantool> auth = require(‘authman’).api(config)-- Using api to get a registration confirmation codetarantool> ok, code = auth.registration(‘example@mail.ru’)-- This code needs to be sent to a user’s email address so that they-- can activate their accounttarantool> code022c1ff1f0b171e51cb6c6e32aefd6ab That’s it for now. The next article will be about using ready Tarantool packages, networking, and implementing OAuth2 in . tarantool-authman Thanks for reading and stay tuned!

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