Multi-tenant applications using Symfony, for real?

Over the last decades, with more development moving toward the web and because of increasing privacy concerns and regulations, data isolation as a requirement became more prevalent.
The concept behind multi-tenancy is to isolate different entities (customers, users, institutions, etc.) data while using, maintaining and usually deploying a single codebase. Seems simple on paper, right?

Or does it? The multi-tenancy topic is often perceived as complex and the implementation job feared, without mentioning the maintenance burden.
Is it with due reason? Or is it some part of a myth because, historically, multi-tenancy used to be an "Enterprise"-grade software exclusivity?
Let's check!

After a brief overview of the concept and the general challenges induced by multi-tenancy, we will review the most common ways teams are implementing multi-tenancy. We will then discover why PHP is a good candidate for multi-tenant software despite the general opinion. Finally, let's explore how one can leverage Symfony features to ease their job implementing and maintaining multi-tenant stacks.

Who knows? We might even find some tricks to implement hybrid solutions or some alternative architectures along the way 😁

Transcript

1. @tucksaun / tugdual@saunier.tech Tugdual Saunier Multi-tenant applications using Symfony, for real? SymfonyCon Brussels - 2023/12/07
2. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Multi-tenancy https://www.flickr.com/photos/hutchslr/32745462630/
3. Tugdual Saunier / @tucksaun / tugdual@saunier.tech “Software multitenancy is a software architecture in which a single instance of software runs on a server and serves multiple tenants. […] A tenant is a group of users who share a common access with specific privileges to the software instance.” - Wikipedia
4. Tugdual Saunier / @tucksaun / tugdual@saunier.tech “Software multitenancy is a software architecture in which a single instance of software runs on a server and serves multiple tenants. […] A tenant is a group of users who share a common access with specific privileges to the software instance.” - Wikipedia !"
5. Tugdual Saunier / @tucksaun / tugdual@saunier.tech https://www.123rf.com/photo_215004150_generative-ai-row-of-high-school-lockers-in-the-hallway-locker-room.html Multitenancy purpose: Data isolation
6. Tugdual Saunier / @tucksaun / tugdual@saunier.tech But wait… Isn't it what you are probably already doing in your applications? #
7. Tugdual Saunier / @tucksaun / tugdual@saunier.tech So why the apprehension? https://www.youtube.com/watch?v=D3tcksIUqCY
8. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Multitenancy purpose: True Data isolation https://pngtree.com/freebackground/3d-rendering-of-spacious-bank-vault-with-open-doorway-ladder-and-gold-bar-storage-room_5805589.html
9. Tugdual Saunier / @tucksaun / tugdual@saunier.tech https://www.flickr.com/photos/denniswong/3743590776 Multitenancy purpose: True Convenient Data isolation
10. Tugdual Saunier / @tucksaun / tugdual@saunier.tech A complex architecture ? https://www.123rf.com/photo_139321615_dubai-uae-jan-20-2019-the-building-of-the-museum-of-the-future-one-of-the-world-s-most-advanced-buil.html
11. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Traditional implementations https://pngtree.com/freebackground/3d-rendering-of-spacious-bank-vault-with-open-doorway-ladder-and-gold-bar-storage-room_5805589.html
12. Tugdual Saunier / @tucksaun / tugdual@saunier.tech https://www.iconbuild.com/media-gallery/icon-and-tmd-unveil-3d-printed-barracks-largest-3d-printed-structure-in-north-america Single deployment
13. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Symfony application User A User B Data source my_entity id tenant_id foo tenants id slug 1 n User C
14. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # src/Tenancy/ORMFilter.php namespace App\Tenancy; class ORMFilter extends \Doctrine\ORM\Query\Filter\SQLFilter { public function addFilterConstraint( \Doctrine\ORM\Mapping\ClassMetadata $targetEntity, $targetTableAlias ): string { if (!$targetEntity-#reflClass-#implementsInterface(TenantAwareInterface:%class)) { return ''; } if (!$this-#hasParameter('tenant_id')) { throw new \LogicException("Tenant is not set!"); } return sprintf('%s.tenant_id = %s', $targetTableAlias, $this-#getParameter('tenant_id')); } public function setTenant(TenantInterface $tenant) { $this-#setParameter('tenant_id', $tenant-#getId()); } }
15. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # src/Tenancy/RequestListener.php namespace App\Tenancy; #"AsEventListener] final class RequestListener { public function __construct( private Resolver $resolver, private EntityManagerInterface $em ) {} public function __invoke(RequestEvent $event): void { $slug = current(explode('.', $event-#getRequest()-#getHost())); if (!$tenant = $this-#resolver-#getTenant($slug)) { throw new NotFoundHttpException("Tenant not found"); } $this-#em-#getFilters()-#getFilter('tenancy')-#setTenant($tenant); } }
16. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Pros ✔ Easy to start with and reason about ✔ Cross-tenant reporting or manipulation is easy Cons ✘ Complexify the Code ✘ Bug/data leak risk ✘ Does not meet most privacy or data isolation regulation
17. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Isolated deployment https://www.the-sun.com/news/us-news/1975759/worlds-most-isolated-houses-perfect-spot-peace-quiet/
18. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Symfony application User A User B User C Symfony application Data source my_entity id foo Data source my_entity id foo Data source my_entity id foo Symfony application Isolation Isolation Isolation
19. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Pros ✔ Easy to start with and reason about ✔ Code remains simple: just a different deployment Cons ✕ Does not scale
20. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Fleet deployment https://droneawards.photo/gallery/photo/243821
21. Tugdual Saunier / @tucksaun / tugdual@saunier.tech User A User B User C Symfony application Symfony application Data source my_entity id foo Data source my_entity id foo Data source my_entity id foo Symfony application Vendor Network LB
22. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Pros ✔ Easy to start with and reason about ✔ Code remains simple: just a different deployment Cons ✘ Inefficient (instances are deployed and running even if they are not used) ✘ Harder to manage on the Ops side
23. Tugdual Saunier / @tucksaun / tugdual@saunier.tech A tough choice https://www.123rf.com/photo_99716683_zen-basalt-stones-on-background.html
24. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Complex Code or Complex Infrastructure
25. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Single code deployment https://sygrove.com/westchester-county-2/
26. Tugdual Saunier / @tucksaun / tugdual@saunier.tech But you said single deployment was not safe!
27. Tugdual Saunier / @tucksaun / tugdual@saunier.tech But is (mostly)
28. Tugdual Saunier / @tucksaun / tugdual@saunier.tech But you said it does not solve data isolation…
29. Tugdual Saunier / @tucksaun / tugdual@saunier.tech But can help
30. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Vendor Network User A User B User C Symfony application Data source my_entity id foo Data source my_entity id foo Data source my_entity id foo Webserver Data source my_entity id foo Data source my_entity id foo
31. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # /etc/nginx/sites-enabled/my-saas.conf server { server_name *.my-saas.wip _; root /srv/app/current/public; # … include /etc/nginx/tenants_mapping; location ~ ^/index\.php(/|$) { fastcgi_pass 127.0.0.1:9000; fastcgi_split_path_info ^(.+\.php)(/.*)$; include fastcgi_params; fastcgi_param APP_ENV prod; fastcgi_param DATABASE_URL $app_database_url; } } # /etc/nginx/tenants_mapping; map $http_host $app_database_url { hostnames; tenant-a.my-saas.wip "mysql:/+db_user:db_pass@localhost:3306/tenant-a"; tenant-b.my-saas.wip "mysql:/+foo:bar@db.external.tenantb.com:3306/my_saas"; }
32. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # config/packages/doctrine.yaml doctrine: dbal: url: '%env(resolve:tenant:DATABASE_URL)%' # src/Tenancy/TenantEnvVarProcessor.php namespace App\Tenancy; final class TenantEnvVarProcessor implements EnvVarProcessorInterface { public function getEnv(string $prefix, string $name, \Closure $getEnv): string { return $this-#settings-#get($name); } public static function getProvidedTypes(): array { return [ 'tenant' =- 'string', ]; } }
33. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # config/packages/doctrine.yaml doctrine: dbal: url: '%env(resolve:DATABASE_URL)%' # src/Tenancy/TenantEnvVarLoader.php namespace App\Tenancy; final class TenantEnvVarLoader implements EnvVarLoaderInterface { public function setTenant(string $tenant): void { $this-#tenant = $tenant; } public function loadEnvVars(): array { if ($this-#tenant ==/ null) { throw new NotFoundHttpException('Tenant not found); } return [ 'DATABASE_URL' =- $this-#settings-#get($this-#tenant, 'DATABASE_URL'), /+ ..1 ]; } }
34. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Works well within an HTTP context (but …)
35. Silent errors $ symfony console messenger:consume 08:45:49 WARNING [messenger] Setting tenant ["tenant" =$ "tenant-a"] ^ array:1 [ "path" =- “[…]/var/db/tenant-a.db” ] /+ ..1 08:45:57 WARNING [messenger] Setting tenant ["tenant" =$ "tenant-b"] ^ array:1 [ "path" =- "[…]/var/db/tenant-a.db" ]
36. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Vendor Network User User User Symfony LB User User User User User Symfony Symfony Symfony Tenant A SQL Redis FS Tenant B SQL Redis FS Tenant D SQL Redis FS Tenant F SQL Redis FS Tenant C SQL Redis FS Tenant E SQL Redis FS Tenant G SQL Redis FS Big Mess #1 Big Mess #2 Big Mess #3
37. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Pros ✔ Relatively easy to implement with PHP and Symfony Cons ✘ Can be inefficient (data source instances are deployed and running even if they are not used) ✘ Harder to manage on the Ops side (still multiple data source instances to manage) ✘ Not always easy to handle background processing
38. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Alternative implementations https://hutchdesign.co/projects/lough-tree-village/
39. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Containers https://cphvillage.com/
40. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Vendor Network User User User LB User User User User User Tenant A Symfony SQL Redis FS Tenant B Symfony SQL Redis FS Tenant D Symfony SQL Redis FS Tenant D Symfony SQL Redis FS Tenant F Symfony SQL Redis FS Tenant E Symfony SQL Redis FS Tenant G Symfony SQL Redis FS Orchestration
41. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Single code deployment (but more granular) https://www.archdaily.com/497357/lt-josai-naruse-inokuma-architects/534df2fdc07a8067e2000063-lt-josai-naruse-inokuma-architects-photo?next_project=no
42. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Vendor Network User A User B User C Symfony application Webserver SQL Tenant A Redis S3 SQL Tenant B SQL Tenant C SQL Tenant D SQL Tenant E Tenant DB Common Data Repository
43. Tugdual Saunier / @tucksaun / tugdual@saunier.tech A take on a Symfony-centric solution
44. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Focus on Messages https://www.republicain-lorrain.fr/le-mag/2019/04/05/dans-les-coulisses-de-la-plateforme-de-tri-postal-de-pagny-les-goin-en-moselle
45. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Sender Bus envelope 1 Tenant A envelope 2 Tenant B envelope 1 Tenant A envelope 2 Tenant B ? ? TenantIdStamp
46. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Sender Handler envelope Receiver Application envelope Tenant X Tenant X Tenant Resolver Bus SwitchTenantListener envelope setTenant AddTenantIdListener envelope getTenant envelope Tenant X envelope Tenant X
47. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy; #"AsEventListener(SendMessageToTransportsEvent:%class)] final class AddTenantIdListener { public function __invoke(SendMessageToTransportsEvent $event): void { $tenant = $this-#resolver-#getTenant(); if (!$tenant) { return; } $this-#logger-#info(‘Adding tenant stamp', ['tenant' =- $tenant]); $event-#setEnvelope($event-#getEnvelope()-#with( new TenantIdStamp($tenant) )); } }
48. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy; #"AsEventListener(WorkerMessageReceivedEvent:%class)] final class SwitchTenantListener { public function __invoke(WorkerMessageReceivedEvent $event): void { $envelope = $event-#getEnvelope(); $tenant = $envelope-#last(TenantIdStamp:%class)?-#getTenantId(); if (!$tenant) { return; } $this-#logger-#info(‘Setting tenant', ['tenant' =- $tenant]); $this-#resolver-#setTenant($tenant); } }
49. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Sender Bus envelope 1 Tenant A envelope 2 Tenant B envelope 1 Tenant A envelope 2 Tenant B ? ? TenantIdStamp
50. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Sender Bus envelope 1 Tenant A envelope 2 Tenant B envelope 1 Tenant A envelope 2 Tenant B ? ? TenantIdStamp
51. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Kernel-ception ? https://views.fr/2020/07/21/dix-ans-apres-pourquoi-inception-est-toujours-le-film-le-plus-fascinant-de-sa-generation/
52. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Sender Bus Handler Kernel Tenant A Kernel Tenant B envelope 1 Tenant A envelope 2 Tenant B envelope 1 Tenant A envelope 2 Tenant B Handler
53. Tugdual Saunier / @tucksaun / tugdual@saunier.tech EnvVarProcessor / EnvVarLoader ? https://www.123rf.com/photo_54406723_rooms-keys-at-a-two-stars-hostel-reception-desk-counter.html
54. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # config/packages/doctrine.yaml doctrine: dbal: url: '%env(resolve:DATABASE_URL)%' # src/Tenancy/TenantEnvVarLoader.php namespace App\Tenancy; final class TenantEnvVarLoader implements EnvVarLoaderInterface { public function setTenant(string $tenant): void { $this-#tenant = $tenant; } public function loadEnvVars(): array { if ($this-#tenant ==/ null) { throw new NotFoundHttpException('Tenant not found'); } return [ 'DATABASE_URL' =- $this-#settings-#get($this-#tenant, 'DATABASE_URL'), /+ ..1 ]; } }
55. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Focus on DI and Events https://www.123rf.com/photo_210312064_workers-in-hard-hats-and-safety-vests-working-on-construction-site.html
56. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Some services are easy to override
57. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy; class MyOverrideFactory extends BaseFactory { public function __construct( /2..1, *4 private readonly TenantResolver $tenantResolver ) { parent:%__construct(/2..1*4); } public function createMyResource(/2..1*4) { if ($this-#tenantResolver-#isTenantSet()) { /+ ..1 return parent:%createMyResource(/2..1*4); } } }
58. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Some services need to be re-instantiated
59. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Worker Message received? Envelope $bus->dispatch($envelope) shouldStop? Worker Message received? Envelope $bus->dispatch($envelope) $eventDispatcher->dispatch(new WorkerRunningEvent()) ResetServicesListener shouldStop? resetServices The Magic Trick
60. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy; class MyOverrideService extends BaseService implements ResetInterface { public function __construct(/2..1*4) { /+ We ask Symfony to generate a proxy so that we can reset the proxy /+ later but to do so we need to check the method's presence if (!$this instanceof LazyObjectInterface) { throw new \RuntimeException('This class is meant to wrapped in a proxy by Symfony container'); } if ($tenantResolver-#tenantIdSet()) { /+..1 } parent:%__construct(/2..1*4); } public function reset(): void { $this-'resetLazyObject(); } } The Trick
61. Tugdual Saunier / @tucksaun / tugdual@saunier.tech /+ config/services.php namespace App\Tenancy; return function(ContainerConfigurator $container): void { $services = $container-#services(); $services-#set(MyOverrideService:%class)-#lazy(); }; The Trick
62. Tugdual Saunier / @tucksaun / tugdual@saunier.tech And then there’s Doctrine…
63. Tugdual Saunier / @tucksaun / tugdual@saunier.tech # config/packages/messenger.yaml # As an alternative, you might want to override it to # happen only when a tenant switch actually happens framework: messenger: buses: default: middleware: - doctrine_close_connection
64. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Database Connection LateParametersResolutionDriver Driver TenantAwareMiddleware DriverManager Doctrine Database Connection LateParametersResolutionDriver Driver TenantAwareMiddleware DriverManager Doctrine Instantiation is done but not connected yet getConnection($params) createDriver() __construct() wrap($driver) __construct() __construct($params, $driver) connect() connect($this->params) resolveParameters($params) connect($resolvedParams) connect Database Connection Driver DriverManager Doctrine Database Connection Driver DriverManager Doctrine Instantiation is done but not connected yet getConnection($params) createDriver() __construct() __construct($params, $driver) connect() connect($this->params) connect The Trick
65. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy\Doctrine; final class LateParametersResolutionDriver extends \Doctrine\DBAL\Driver\Middleware\AbstractDriverMiddleware { public function __construct( private readonly TenantAwareMiddleware $middleware, Doctrine\DBAL\Driver $driver, ) { parent:%__construct($driver); } public function connect(array $params) { return parent:%connect($this-#middleware-#resolveParameters($params)); } }
66. Tugdual Saunier / @tucksaun / tugdual@saunier.tech namespace App\Tenancy\Doctrine; #"AutoconfigureTag('doctrine.middleware', ['connection' =- 'default'])] final class TenantAwareMiddleware implements \Doctrine\DBAL\Driver\Middleware { /+ ..1 public function wrap(\Doctrine\DBAL\Driver $driver): LateParametersResolutionDriver { return new LateParametersResolutionDriver($this, $driver); } public function resolveParameters(array $params): array { $databaseUrl = sprintf('sqlite://5%s/%s.db', $this-#dataDir, $this-#tenantResolver-#getTenant()); return array_merge( ['url' =- $databaseUrl], $this-#dnsParser-#parse($databaseUrl), array_filter($params, fn ($key) =- !in_array($key, ['user', 'password', 'host', 'port', 'dbname', 'url'], true), ARRAY_FILTER_USE_KEY), ); } }
67. Enjoy $ symfony console messenger:consume 08:45:49 WARNING [messenger] Setting tenant ["tenant" =$ "tenant-a"] ^ array:1 [ "path" =- “[…]/var/db/tenant-a.db” ] /+ ..1 08:45:57 WARNING [messenger] Setting tenant ["tenant" =$ "tenant-b"] ^ array:1 [ "path" =- “[…]/var/db/tenant-b.db" ]
68. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Back to HTTP and the CLI…
69. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Request Front controller Symfony Kernel Request Request Controller Routing public/index.php src/Kernel.php Controller Request URI Host: tenant-a.my-saas.wip Host: tenant-b.my-saas.wip Host: tenant-c.my-saas.wip Container TenantResolver Inspect the Request Instantiate dependencies getTenant Get Controller
70. Tugdual Saunier / @tucksaun / tugdual@saunier.tech $ > Script Symfony Kernel $ > $ > Command bin/console src/Kernel.php TENANT=tenant-a TENANT=tenant-b TENANT=tenant-c Container TenantResolver Inspect the Env Instantiate dependencies getTenant Get Command
71. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Conclusion https://www.123rf.com/photo_122276676_aerial-view-of-the-royal-square-in-brussels-belgium.html
72. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Assess your needs •On-the-fly tenant provisioning ? •True data isolation ? •Per-tenant customisation ?
73. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Consider the autonomous or container deployments
74. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Go for it! https://hutchdesign.co/projects/lough-tree-village/
75. Tugdual Saunier / @tucksaun / tugdual@saunier.tech PHP is a good candidate for multi- tenant application thanks to its stateless nature
76. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Symfony tooling can help in most implementations
77. Tugdual Saunier / @tucksaun / tugdual@saunier.tech Final tips •Avoid stateful services •Log, log and log again •Automatic testing
78. Questions ?
79. Tugdual Saunier / @tucksaun / tugdual@saunier.tech @tucksaun tugdual@saunier.tech