vmakhaev / http

http client and server

http - a Tarantool rock for an HTTP client and a server

Getting Started

Prerequisites

• Tarantool 1.6.5+ with header files (tarantool && tarantool-dev packages)

Installation

Clone repository and then build it using CMake:

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

You can also use LuaRocks:

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

See [tarantool/rocks][TarantoolRocks] for LuaRocks configuration details.

Usage

    client = require('http.client')
    print(client.get("http://mail.ru/").status)

HTTP client

Any kind of HTTP 1.1 query (no SSL support yet).

http.client.request(method, url, body[, opts])

Issue an HTTP request at the given URL (url). method can be either GET or POST.

If body is nil, the body is an empty string, otherwise the string passed in body.

opts is an optional Lua table with methods, and may contain the following keys:

• headers - additional HTTP headers to send to the server

Returns a Lua table with:

• status - HTTP response status
• reason - HTTP response status text
• headers - a Lua table with normalized HTTP headers
• body - response body
• proto - protocol version

Example

    r = require('http.client').request('GET', 'http://google.com')
    r = require('http.client').request('POST', 'http://google.com', 'text=123', {})

HTTP server

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, ports numbers below 1024 may be unavailable.

The server can be started and stopped any time. Multiple servers can be creatd.

To start a server:

• create it: httpd = require('http.server').new(...)
• configure "routing" httpd:route(...)
• start it with httpd:start()
• stop with httpd:stop()

server.new() - create an HTTP 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 on HTTP request header size
• header_timeout (default: 100 seconds) - a time out until the server stops reading HTTP headers sent by the client. The server closes the client connection if the client can't manage to send its headers in the given amount of time.
• app_dir (default: '.', 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 backraces to client (like PHP)
• log_errors - log application errors using log.error()

Using routes

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

Routes can be defined using either:

1. and exact match, e.g. "index.php"
2. with simple regular expressions
3. with 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 conigure a route, use 'route()' method of 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)
...

route() first argument is a Lua table with one or several keys:

• file - a template file name (if relative, then to path {app_dir}/tempalates, where app_dir is the path set when creating the server). If no template file name extention is provided, the extention 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

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

A typical usage is to avoid passing file and template arguments, since these 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 form 'filename#functionname'. In that case, handler body is taken from a file in {app_dir}/controllers directory.

Summary of the stuff in app_dir

• public - is a path to store static content. Anything in this path defines a route which matches the file name, and the server serves this file automatically, as is. Note, that the server doesn't use sendfile(), and reads the entire content of the file in memory before passing it to the client. Caching is used, unless is turned on. So this is suitable for large files, use nginx instad.
• templates - a path to templates
• controllers - a path to Lua controllers lua. For example, controller name 'module.submodule#foo' maps to {app_dir}/controllers/module.submodule.lua.

Route handlers

A route handler is a function which accept one argument - Request and returns one value - Response.

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

Fields and methods of 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 lower case, all headers joined together into a single string.
• req.peer - a Lua table with information about remote peer (like socket:peer())
• tostring(req) - returns a string representation of the request
• req:request_line() - returns request body
• req:read(delimiter|chunk|{delimiter = x, chunk = x}, timeout) - read raw request body as stream (see socket:read())
• req:json() - returns lua table from json JSON request
• req:post_param(name) - returns a single POST request 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 withall 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 exact URL
• req:render({}) - create Response object with rendered template
• req:redirect_to - create Response object with HTTP redirect

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

Working with cookies

Do 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 cookie() method as well, but pass in 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

        -- do 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 into a template, use:

• <% lua-here %> - insert any Lua code, including multi-line. Can be used in any location in the template.
• % lua-here - a single line Lua substitution. Can only be present in 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 and inserts the result into HTML. HTML special characters, such as <, >, &, " are escaped.
• == (e.g., <%== value + 10 %>) - the same, but with no escaping.

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

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

Template helpers

Helpers are special functions for use in HTML templates, available in all templates. They 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 given 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 argument of the hook is 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.

For additional examples, see documentation and tests.

See Also

• Tarantool
• Documentation
• Tests