Developing cacheable PHP applications Thijs Feryn

Slow websites suck

Hi, I’m Thijs

I’m @ThijsFeryn on Twitter

I’m an Evangelist At

I’m an Evangelist At

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Cache

Don’t recompute if the data hasn’t changed

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What if we could design our software with HTTP caching in mind?

✓Portability ✓Developer empowerment ✓Control ✓Consistent caching behavior Caching state of mind

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Reverse caching proxy

Normally User Server

With ReCaPro * User ReCaPro Server * Reverse Caching Proxy

Content Delivery Network

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HTTP caching mechanisms Expires: Sat, 09 Sep 2017 14:30:00 GMT Cache-control: public, max-age=3600, s-maxage=86400 Cache-control: private, no-cache, no-store

In an ideal world

✓Stateless ✓Well-defined TTL ✓Cache / no-cache per resource ✓Cache variations ✓Conditional requests ✓HTTP fragments for non- cacheable content In an ideal world

Reality sucks

Common problems

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Time To Live

Cache variations

Authentication

Legacy

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Twig templates

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✓Multi-lingual (Accept-Language) ✓Nav ✓Header ✓Footer ✓Main ✓Login page & private content

composer require symfony/flex composer require annotations twig translation

render('index.twig'); } } src/Controller/DefaultController.php

{% block title %}{% endblock %} templates/base.twig

{% extends "base.twig" %} {% block title %}Home{% endblock %} {% block content %}

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Mauris consequat orci eget libero sollicitudin, non ultrices turpis mollis. Aliquam sit amet tempus elit. Ut viverra risus enim, ut venenatis justo accumsan nec. Praesent a dolor tellus. Maecenas non mauris leo. Pellentesque lobortis turpis at dapibus laoreet. Mauris rhoncus nulla et urna mollis, et lobortis magna ornare. Etiam et sapien consequat, egestas felis sit amet, dignissim enim.

Quisque quis mollis justo, imperdiet fermentum velit. Aliquam nulla justo, consectetur et diam non, luctus commodo metus. Vestibulum fermentum efficitur nulla non luctus. Nunc lorem nunc, mollis id efficitur et, aliquet sit amet ante. Sed ipsum turpis, vehicula eu semper eu, malesuada eget leo. Vestibulum venenatis dui id pulvinar suscipit. Etiam nec massa pharetra justo pharetra dignissim quis non magna. Integer id convallis lectus. Nam non ullamcorper metus. Ut vestibulum ex ut massa posuere tincidunt. Vestibulum hendrerit neque id lorem rhoncus aliquam. Duis a facilisis metus, a faucibus nulla.

{% endblock %} templates/index.twig

• Home
• {{ 'log_in' | trans }}
• Private

templates/nav.twig

---

Footer templates/footer.twig

home: Home welcome : Welcome to the site rendered : Rendered at %date% example : An example page log_in : Log in login : Login log_out : Log out username : Username password : Password private : Private privatetext : Looks like some very private data translations/messages.en.yml

home: Start welcome : Welkom op de site rendered : Samengesteld op %date% example : Een voorbeeldpagina log_in : Inloggen login : Login log_out : Uitloggen username : Gebruikersnaam password : Wachtwoord private : Privé privatetext : Deze tekst ziet er vrij privé uit translations/messages.nl.yml

getRequest(); $preferredLanguage = $request->getPreferredLanguage(); if(null !== $preferredLanguage) { $request->setLocale($preferredLanguage); } } } src/EventListener/LocaleListener.php

services: _defaults: autowire: true autoconfigure: true public: false App\: resource: '../src/*' exclude: '../src/{Entity,Migrations,Tests,Kernel.php}' App\Controller\: resource: '../src/Controller' tags: ['controller.service_arguments'] App\EventListener\LocaleListener: tags: - { name: kernel.event_listener, event: kernel.request, priority: 100} config/services.yml

Accept-Language: en Accept-Language: nl VS

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The mission Maximum Cacheability

Cache-control

Cache-Control: public, s-maxage=500

render('index.twig') ->setSharedMaxAge(500) ->setPublic(); } }

Conditional requests

Only fetch payload that has changed

HTTP/1.1 200 OK

Otherwise: HTTP/1.1 304 Not Modified

Conditional requests HTTP/1.1 200 OK Host: localhost Etag: 7c9d70604c6061da9bb9377d3f00eb27 Content-type: text/html; charset=UTF-8 Hello world output GET / HTTP/1.1 Host: localhost User-Agent: curl/7.48.0

Conditional requests HTTP/1.0 304 Not Modified Host: localhost Etag: 7c9d70604c6061da9bb9377d3f00eb27 GET / HTTP/1.1 Host: localhost User-Agent: curl/7.48.0 If-None-Match: 7c9d70604c6061da9bb9377d3f00eb27

Conditional requests HTTP/1.1 200 OK Host: localhost Last-Modified: Fri, 22 Jul 2016 10:11:16 GMT Content-type: text/html; charset=UTF-8 Hello world output GET / HTTP/1.1 Host: localhost User-Agent: curl/7.48.0

Conditional requests HTTP/1.0 304 Not Modified Host: localhost Last-Modified: Fri, 22 Jul 2016 10:11:16 GMT GET / HTTP/1.1 Host: localhost User-Agent: curl/7.48.0 If-Last-Modified: Fri, 22 Jul 2016 10:11:16 GMT

composer require symfony-bundles/redis-bundle

redis = $redis; $this->logger = $logger; } protected function isModified(Request $request, $etag) { if ($etags = $request->getETags()) { return in_array($etag, $etags) || in_array('*', $etags); } return true; } ... src/EventListener/ConditionalRequestListener.php

{ $this->redis = $redis; $this->logger = $logger; } protected function isModified(Request $request, $etag) { if ($etags = $request->getETags()) { return in_array($etag, $etags) || in_array('*', $etags); } return true; } public function onKernelRequest(GetResponseEvent $event) { $request = $event->getRequest(); $etag = $this->redis->get('etag:'.md5($request->getUri())); if(!$this->isModified($request,$etag)) { $event->setResponse(Response::create('Not Modified',Response::HTTP_NOT_MODIFIED)); } } public function onKernelResponse(FilterResponseEvent $event) { $response = $event->getResponse(); $request = $event->getRequest(); $etag = md5($response->getContent()); $response->setEtag($etag); if($this->isModified($request,$etag)) { $this->redis->set('etag:'.md5($request->getUri()),$etag); } } } src/EventListener/ConditionalRequestListener.php

Do not cache

Cache-Control: private, no-store

/** * @Route("/private", name="private") */ public function private() { $response = $this ->render('private.twig') ->setPrivate(); $response->headers->addCacheControlDirective('no-store'); return $response; } Dot not cache private page

session cookie No cache

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Code renders single HTTP response

Lowest common denominator: no cache

Block caching

Edge Side Includes ✓Placeholder ✓Parsed by Varnish ✓Output is a composition of blocks ✓State per block ✓TTL per block

Surrogate-Capability: key="ESI/1.0" Surrogate-Control: content="ESI/1.0" Varnish Backend Parse ESI placeholders Varnish

ESI vs AJAX

✓ Server-side ✓ Standardized ✓ Processed on the “edge”, no in the browser ✓ Generally faster Edge-Side Includes - Sequential - One fails, all fail - Limited implementation in Varnish

✓ Client-side ✓ Common knowledge ✓ Parallel processing ✓ Graceful degradation AJAX - Processed by the browser - Extra roundtrips - Somewhat slower

Subrequests

/** * @Route("/", name="home") */ public function index() { return $this ->render('index.twig') ->setPublic() ->setSharedMaxAge(500); } /** * @Route("/header", name="header") */ public function header() { $response = $this ->render('header.twig') ->setPrivate(); $response->headers->addCacheControlDirective('no-store'); return $response; } /** * @Route("/footer", name="footer") */ public function footer() { $response = $this->render('footer.twig'); $response ->setSharedMaxAge(500) ->setPublic(); return $response; } /** * @Route("/nav", name="nav") */ public function nav() { $response = $this->render('nav.twig'); $response ->setVary('X-Login',false) ->setSharedMaxAge(500) ->setPublic(); return $response; } Controller action per fragment

Problem: no language cache variation

Vary: Accept-Language

getResponse(); $response->setVary('Accept-Language',false); } } src/EventListener/VaryListener.php

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✓Navigation page ✓Private page Weak spots Not cached because of stateful content

Move state client-side

Replace PHP session with JSON Web Tokens

JWT eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJhZG1pb iIsImV4cCI6MTQ5NTUyODc1NiwibG9naW4iOnRydWV9.u4Idy- SYnrFdnH1h9_sNc4OasORBJcrh2fPo1EOTre8 ✓3 parts ✓Dot separated ✓Base64 encoded JSON ✓Header ✓Payload ✓Signature (HMAC with secret)

eyJzdWIiOiJhZG1pbiIsIm V4cCI6MTQ5NTUyODc1Niwi bG9naW4iOnRydWV9 { "alg": "HS256", "typ": "JWT" } { "sub": "admin", "exp": 1495528756, "login": true } HMACSHA256( base64UrlEncode(header) + "." + base64UrlEncode(payload), secret ) eyJhbGciOiJIUzI1NiIsI nR5cCI6IkpXVCJ9 u4Idy- SYnrFdnH1h9_sNc4OasOR BJcrh2fPo1EOTre8

JWT Cookie:token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJz dWIiOiJhZG1pbiIsImV4cCI6MTQ5NTUyODc1NiwibG9naW4iOnRydW V9.u4Idy-SYnrFdnH1h9_sNc4OasORBJcrh2fPo1EOTre8 ✓Stored in a cookie ✓Can be validated by Varnish ✓Payload can be processed by any language (e.g. Javascript)

sub jwt { std.log("Ready to perform some JWT magic"); if(cookie.isset("jwt_cookie")) { #Extract header data from JWT var.set("token", cookie.get("jwt_cookie")); var.set("header", regsub(var.get("token"),"([^\.]+)\.[^\.]+\.[^\.]+","\1")); var.set("type", regsub(digest.base64url_decode(var.get("header")),{"^.*?"typ"\s*:\s*"(\w+)".*?$"},"\1")); var.set("algorithm", regsub(digest.base64url_decode(var.get("header")),{"^.*?"alg"\s*:\s*"(\w+)".*?$"},"\1")); #Don't allow invalid JWT header if(var.get("type") == "JWT" && var.get("algorithm") == "HS256") { #Extract signature & payload data from JWT var.set("rawPayload",regsub(var.get("token"),"[^\.]+\.([^\.]+)\.[^\.]+$","\1")); var.set("signature",regsub(var.get("token"),"^[^\.]+\.[^\.]+\.([^\.]+)$","\1")); var.set("currentSignature",digest.base64url_nopad_hex(digest.hmac_sha256(var.get("key"),var.get("header") + "." + var.get("rawPayload")))); var.set("payload", digest.base64url_decode(var.get("rawPayload"))); var.set("exp",regsub(var.get("payload"),{"^.*?"exp"\s*:\s*([0-9]+).*?$"},"\1")); var.set("jti",regsub(var.get("payload"),{"^.*?"jti"\s*:\s*"([a-z0-9A-Z_\-]+)".*?$"},"\1")); var.set("userId",regsub(var.get("payload"),{"^.*?"uid"\s*:\s*"([0-9]+)".*?$"},"\1")); var.set("roles",regsub(var.get("payload"),{"^.*?"roles"\s*:\s*"([a-z0-9A-Z_\-, ]+)".*?$"},"\1")); #Only allow valid userId if(var.get("userId") ~ "^\d+$") { #Don't allow expired JWT if(std.time(var.get("exp"),now) >= now) { #SessionId should match JTI value from JWT if(cookie.get(var.get("sessionCookie")) == var.get("jti")) { #Don't allow invalid JWT signature if(var.get("signature") == var.get("currentSignature")) { #The sweet spot set req.http.X-login="true"; } else { std.log("JWT: signature doesn't match. Received: " + var.get("signature") + ", expected: " + var.get("currentSignature")); } } else { std.log("JWT: session cookie doesn't match JTI." + var.get("sessionCookie") + ": " + cookie.get(var.get("sessionCookie")) + ", JTI:" + var.get("jti")); } } else { std.log("JWT: token has expired"); } } else { std.log("UserId '"+ var.get("userId") +"', is not numeric"); } } else { std.log("JWT: type is not JWT or algorithm is not HS256"); } std.log("JWT processing finished. UserId: " + var.get("userId") + ". X-Login: " + req.http.X-login); } #Look for full private content if(req.url ~ "/node/2" && req.url !~ "^/user/login") { if(req.http.X-login != "true") { return(synth(302,"/user/login?destination=" + req.url)); } } } Insert incomprehensible Varnish VCL code here …

X-Login: true End result: X-Login: false Custom request header set by Varnish

Extra cache variation required

Vary: Accept-Language, X-Login Content for logged-in & anonymous differs


 function getCookie(name) {
 var value = "; " + document.cookie;
 var parts = value.split("; " + name + "=");
 if (parts.length == 2) return parts.pop().split(";").shift();
 }
 function parseJwt (token) {
 var base64Url = token.split('.')[1];
 var base64 = base64Url.replace('-', '+').replace('_', '/');
 return JSON.parse(window.atob(base64));
 };
 $(document).ready(function(){
 if ($.cookie('token') != null ){
 var token = parseJwt($.cookie("token"));
 $("#usernameLabel").html(', ' + token.sub);
 }
 });
 Parse JWT in Javascript

Does not require backend access

composer require firebase/php-jwt

key = $key; $this->username = $username; $this->password = $password; } public function jwt($username) { return JWT::encode([ 'sub'=>$username, 'exp'=>time() + (4 * 24 * 60 * 60), 'login'=>true, ],$this->key); } public function createCookie($username) { return new Cookie("token",$this->jwt($username), time() + (3600 * 48), '/', null, false, false); } public function validate($token) { src/Service/JwtAuthentication.php

$this->password = $password; } public function jwt($username) { return JWT::encode([ 'sub'=>$username, 'exp'=>time() + (4 * 24 * 60 * 60), //'exp'=>time() + 60, 'login'=>true, ],$this->key); } public function createCookie($username) { return new Cookie("token",$this->jwt($username), time() + (3600 * 48), '/', null, false, false); } public function validate($token) { try { $data = JWT::decode($token,$this->key,['HS256']); $data = (array)$data; if($data['sub'] !== $this->username) { return false; } return true; } catch(\UnexpectedValueException $e) { return false; } } } src/Service/JwtAuthentication.php

services: App\Service\JwtAuthentication: arguments: $key: '%env(JWT_KEY)%' $username: '%env(JWT_USERNAME)%' $password: '%env(JWT_PASSWORD)%' src/Service/JwtAuthentication.php

###> JWT authentication ### JWT_KEY=SlowWebSitesSuck JWT_USERNAME=admin JWT_PASSWORD=$2y$10$431rvq1qS9ewNFP0Gti/o.kBbuMK4zs8IDTLlxm5uzV7cbv8wKt0K ###< JWT authentication ### .env

/** * @Route("/login", name="login", methods="GET") */ public function login(Request $request, JwtAuthentication $jwt) { if($jwt->validate($request->cookies->get('token'))) { return new RedirectResponse($this->generateUrl('home')); } $response = $this->render('login.twig',['loginLogoutUrl'=>$this- >generateUrl('login'),'loginLogoutLabel'=>'log_in']); $response ->setSharedMaxAge(500) ->setVary('X-Login',false) ->setPublic(); return $response; } /** * @Route("/login", name="loginpost", methods="POST") */ public function loginpost(Request $request, JwtAuthentication $jwt) { $username = $request->get('username'); $password = $request->get('password'); if(!$username || !$password || getenv('JWT_USERNAME') != $username || ! password_verify($password,getenv('JWT_PASSWORD'))) { return new RedirectResponse($this->generateUrl('login')); } $response = new RedirectResponse($this->generateUrl('home')); $response->headers->setCookie($jwt->createCookie($username)); return $response; } src/Controller/DefaultController.php

/** * @Route("/logout", name="logout") */ public function logout() { $response = new RedirectResponse($this->generateUrl('login')); $response->headers->clearCookie('token'); return $response; } src/Controller/DefaultController.php

/** * @Route("/nav", name="nav") */ public function nav(Request $request, JwtAuthentication $jwt) { if($jwt->validate($request->cookies->get('token'))) { $loginLogoutUrl = $loginLogoutUrl = $this->generateUrl('logout'); $loginLogoutLabel = 'log_out'; } else { $loginLogoutUrl = $this->generateUrl('login'); $loginLogoutLabel = 'log_in'; } $response = $this->render('nav.twig', ['loginLogoutUrl'=>$loginLogoutUrl,'loginLogoutLabel'=>$loginLogoutLabel]); $response ->setVary('X-Login',false) ->setSharedMaxAge(500) ->setPublic(); return $response; } src/Controller/DefaultController.php

{% extends "base.twig" %} {% block title %}Login{% endblock %} {% block content %} {% endblock %} templates/login.twig

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Cookie: token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1Ni J9.eyJzdWIiOiJhZG1pbiIsImV4cCI6MTUyMDk0M jExNSwibG9naW4iOnRydWV9._161Lf8BKkbzjqVv 5d62O5aMdCotKvCqd7F8qFqZC2Y

With the proper VCL, Varnish can process the JWT and make cache variations for authenticated & anonymous content

https://github.com/ThijsFeryn/ cacheable-sites-symfony4

https://feryn.eu https://twitter.com/ThijsFeryn https://instagram.com/ThijsFeryn

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