HTTP server for Tarantool 1.7.5+

Note: In Tarantool 1.7.5+, a full-featured HTTP client is available aboard. For Tarantool 1.6.5+, both HTTP server and client are available here.

Table of contents

• Prerequisites
• Installation
• Usage
• Creating a server
• Using routes
• Contents of app_dir
• Route handlers
  • Fields and methods of the Request object
  • Fields and methods of the Response object
  • Examples
• Working with stashes
  • Special stash names
• Working with cookies
• Rendering a template
• Template helpers
• Hooks
  • handler(httpd, req)
  • before_dispatch(httpd, req)
  • after_dispatch(cx, resp)
• See also

Prerequisites

• Tarantool 1.7.5+ with header files (tarantool && tarantool-dev packages)

Installation

You can:

• clone the repository and build the http module using CMake:

  git clone https://github.com/tarantool/http.git
  cd http && cmake . -DCMAKE_BUILD_TYPE=RelWithDebugInfo
  make
  make install

• install the http module using tarantoolctl:

  tarantoolctl rocks install http

• install the http module using LuaRocks (see TarantoolRocks for LuaRocks configuration details):

  luarocks install https://raw.githubusercontent.com/tarantool/http/master/http-scm-1.rockspec --local

Usage

The server is an object which is configured with HTTP request handlers, routes (paths), templates, and a port to bind to. Unless Tarantool is running under a superuser, port numbers below 1024 may be unavailable.

The server can be started and stopped anytime. Multiple servers can be created.

To start a server:

1. Create it with httpd = require('http.server').new(...).
2. Configure routing with httpd:route(...).
3. Start it with httpd:start().

To stop the server, use httpd:stop().

Creating a server

httpd = require('http.server').new(host, port[, { options } ])

host and port must contain the interface and port to bind to.

options may contain:

• max_header_size (default is 4096 bytes) - a limit for HTTP request header size.
• header_timeout (default: 100 seconds) - a timeout until the server stops reading HTTP headers sent by the client. The server closes the client connection if the client doesn't send its headers within the given amount of time.
• app_dir (default is '.', the server working directory) - a path to the directory with HTML templates and controllers.
• handler - a Lua function to handle HTTP requests (this is a handler to use if the module "routing" functionality is not needed).
• charset - the character set for server responses of type text/html, text/plain and application/json.
• display_errors - return application errors and backtraces to the client (like PHP).
• log_errors - log application errors using log.error().
• log_requests - log incoming requests.

Using routes

It is possible to automatically route requests between different handlers, depending on the request path. The routing API is inspired by Mojolicious API.

Routes can be defined using:

• an exact match (e.g. "index.php")
• simple regular expressions
• extended regular expressions

Route examples:

'/'                 -- a simple route
'/abc'              -- a simple route
'/abc/:cde'         -- a route using a simple regular expression
'/abc/:cde/:def'    -- a route using a simple regular expression
'/ghi*path'         -- a route using an extended regular expression

To configure a route, use the route() method of the httpd object:

httpd:route({ path = '/path/to' }, 'controller#action')
httpd:route({ path = '/', template = 'Hello <%= var %>' }, handle1)
httpd:route({ path = '/:abc/cde', file = 'users.html.el' }, handle2)
httpd:route({ path = '/objects', method = 'GET' }, handle3)
...

The first argument for route() is a Lua table with one or more keys:

• file - a template file name (can be relative to. {app_dir}/templates, where app_dir is the path set when creating the server). If no template file name extension is provided, the extension is set to ".html.el", meaning HTML with embedded Lua.
• template - template Lua variable name, in case the template is a Lua variable. If template is a function, it's called on every request to get template body. This is useful if template body must be taken from a database.
• path - route path, as described earlier.
• name - route name.
• method - method on the route like POST, GET, PUT, DELETE

The second argument is the route handler to be used to produce a response to the request.

The typical usage is to avoid passing file and template arguments, since they take time to evaluate, but these arguments are useful for writing tests or defining HTTP servers with just one "route".

The handler can also be passed as a string of the form 'filename#functionname'. In that case, the handler body is taken from a file in the {app_dir}/controllers directory.

Contents of app_dir

• public - a path to static content. Everything stored on this path defines a route which matches the file name, and the HTTP server serves this file automatically, as is. Notice that the server doesn't use sendfile(), and it reads the entire content of the file into the memory before passing it to the client. ??? Caching is not used, unless turned on. So this is not suitable for large files, use nginx instead.
• templates - a path to templates.
• controllers - a path to *.lua files with Lua controllers. For example, the controller name 'module.submodule#foo' is mapped to {app_dir}/controllers/module.submodule.lua.

Route handlers

A route handler is a function which accepts one argument (Request) and returns one value (Response).

function my_handler(req)
    -- req is a Request object
    -- resp is a Response object
    local resp = req:render({text = req.method..' '..req.path })
    resp.headers['x-test-header'] = 'test';
    resp.status = 201
    return resp
end

Fields and methods of the Request object

• req.method - HTTP request type (GET, POST etc).
• req.path - request path.
• req.query - request arguments.
• req.proto - HTTP version (for example, { 1, 1 } is HTTP/1.1).
• req.headers - normalized request headers. A normalized header is in the lower case, all headers joined together into a single string.
• req.peer - a Lua table with information about the remote peer (like socket:peer()).
• tostring(req) - returns a string representation of the request.
• req:request_line() - returns the request body.
• req:read(delimiter|chunk|{delimiter = x, chunk = x}, timeout) - reads the raw request body as a stream (see socket:read()).
• req:json() - returns a Lua table from a JSON request.
• req:post_param(name) - returns a single POST request a parameter value. If name is nil, returns all parameters as a Lua table.
• req:query_param(name) - returns a single GET request parameter value. If name is nil, returns a Lua table with all arguments.
• req:param(name) - any request parameter, either GET or POST.
• req:cookie(name) - to get a cookie in the request.
• req:stash(name[, value]) - get or set a variable "stashed" when dispatching a route.
• req:url_for(name, args, query) - returns the route's exact URL.
• req:render({}) - create a Response object with a rendered template.
• req:redirect_to - create a Response object with an HTTP redirect.

Fields and methods of the Response object

• resp.status - HTTP response code.
• resp.headers - a Lua table with normalized headers.
• resp.body - response body (string|table|wrapped_iterator).
• resp:setcookie({ name = 'name', value = 'value', path = '/', expires = '+1y', domain = 'example.com')) - adds Set-Cookie headers to resp.headers.

Examples

function my_handler(req)
    return {
        status = 200,
        headers = { ['content-type'] = 'text/html; charset=utf8' },
        body = [[
            <html>
                <body>Hello, world!</body>
            </html>
        ]]
    }
end

Working with stashes

function hello(self)
    local id = self:stash('id')    -- here is :id value
    local user = box.space.users:select(id)
    if user == nil then
        return self:redirect_to('/users_not_found')
    end
    return self:render({ user = user  })
end

httpd = box.httpd.new('127.0.0.1', 8080)
httpd:route(
    { path = '/:id/view', template = 'Hello, <%= user.name %>' }, hello)
httpd:start()

Special stash names

• controller - the controller name.
• action - the handler name in the controller.
• format - the current output format (e.g. html, txt). Is detected automatically based on the request's path (for example, /abc.js sets format to js). When producing a response, format is used to serve the response's 'Content-type:'.

Working with cookies

To get a cookie, use:

function show_user(self)

    local uid = self:cookie('id')

    if uid ~= nil and string.match(uid, '^%d$') ~= nil then

        local user = box.select(users, 0, uid)
        return self:render({ user = user })
    end

    return self:redirect_to('/login')
end

To set a cookie, use the cookie() method as well, but pass to it a Lua table defining the cookie to be set:

function user_login(self)

    local login = self:param('login')
    local password = self:param('password')

    local user = box.select(users, 1, login, password)
    if user ~= nil then
        return self:redirect_to('/'):
            set_cookie({ name = 'uid', value = user[0], expires = '+1y' })
    end

    -- to login again and again and again
    return self:redirect_to('/login')
end

The table must contain the following fields:

• name

• value

• path (optional; if not set, the current request path is used)

• domain (optional)

• expires - cookie expire date, or expire offset, for example:

  • 1d - 1 day
  • +1d - the same
  • 23d - 23 days
  • +1m - 1 month (30 days)
  • +1y - 1 year (365 days)

Rendering a template

Lua can be used inside a response template, for example:

<html>
    <head>
        <title><%= title %></title>
    </head>
    <body>
        <ul>
            % for i = 1, 10 do
                <li><%= item[i].key %>: <%= item[i].value %></li>
            % end
        </ul>
    </body>
</html>

To embed Lua code into a template, use:

• <% lua-here %> - insert any Lua code, including multi-line. Can be used anywhere in the template.
• % lua-here - a single-line Lua substitution. Can only be present at the beginning of a line (with optional preceding spaces and tabs, which are ignored).

A few control characters may follow %:

• = (e.g., <%= value + 1 %>) - runs the embedded Lua code and inserts the result into HTML. Special HTML characters, such as <, >, &, ", are escaped.
• == (e.g., <%== value + 10 %>) - the same, but without escaping.

A Lua statement inside the template has access to the following environment:

1. Lua variables defined in the template,
2. stashed variables,
3. variables standing for keys in the render table.

Template helpers

Helpers are special functions that are available in all HTML templates. These functions must be defined when creating an httpd object.

Setting or deleting a helper:

-- setting a helper
httpd:helper('time', function(self, ...) return box.time() end)
-- deleting a helper
httpd:helper('some_name', nil)

Using a helper inside an HTML template:

<div>
    Current timestamp: <%= time() %>
</div>

A helper function can receive arguments. The first argument is always the current controller. The rest is whatever is passed to the helper from the template.

Hooks

It is possible to define additional functions invoked at various stages of request processing.

handler(httpd, req)

If handler is present in httpd options, it gets involved on every HTTP request, and the built-in routing mechanism is unused (no other hooks are called in this case).

before_dispatch(httpd, req)

Is invoked before a request is routed to a handler. The first argument of the hook is the HTTP request to be handled. The return value of the hook is ignored.

This hook could be used to log a request, or modify request headers.

after_dispatch(cx, resp)

Is invoked after a handler for a route is executed.

The arguments of the hook are the request passed into the handler, and the response produced by the handler.

This hook can be used to modify the response. The return value of the hook is ignored.

See also

• Tarantool project on GitHub
• Tests for the http module