Drupal Multisite presentation from Do It With Drupal seminar 2008

1. Demystifying
Multisite Architecture
John VanDyk and James Walker
Do It With Drupal, December 2008
1

2. What is Multisite?
How Multisite Works
Sharing Information Between Sites
2
three sections to this presentation, lots of time for questions

3. http://www.example.com
http://banana.example.com
http://www.example.com/apple
http://pancakeblog.net
3
You can always have multiple Drupal sites on a server, with multiple copies of Drupal

4. http://www.example.com
http://banana.example.com
http://www.example.com/apple
http://pancakeblog.net
4
We’re talking about having multiple sites on ONE copy of Drupal.

5. Why?
5

6. 6

7. • Only one copy of the codebase
6

8. • Only one copy of the codebase
• Only one codebase to upgrade
6

9. • Only one copy of the codebase
• Only one codebase to upgrade
• Only one set of files to debug
6

10. • Only one copy of the codebase
• Only one codebase to upgrade
• Only one set of files to debug
• Still have flexibility for site-specific modules
6

11. 7
Drupal has three essential components.
The filesystem contains the files that make up the Drupal codebase.

12. $db_url = 'mysqli://joe:secret@localhost/example';
8
The database contains content and most configuration settings.

13. example
$db_url = 'mysqli://joe:secret@localhost/example';
8
The database contains content and most configuration settings.

14. example
$db_url = 'mysqli://joe:secret@localhost/example';
8
The database contains content and most configuration settings.

15. 9
The files directory contains uploaded files.

16. 10
If using private files, the files directory can be outside of the web root.

17. <?php
require_once './includes/bootstrap.inc';
drupal_bootstrap(FULL);
11

18. CONFIGURATION: initialize configuration.
EARLY PAGE CACHE
DATABASE: initialize database layer.
ACCESS: identify and reject banned hosts.
SESSION: initialize session handling.
LATE PAGE CACHE
LANGUAGE: identify the language
PATH: path handling
FULL: Drupal is fully loaded
12

19. CONFIGURATION: initialize configuration.
EARLY PAGE CACHE
DATABASE: initialize database layer.
ACCESS: identify and reject banned hosts.
SESSION: initialize session handling.
LATE PAGE CACHE
LANGUAGE: identify the language
PATH: path handling
FULL: Drupal is fully loaded
13
Multisite happens here.

20. We’ve got a request for http://www.example.com/
That’s from host www.example.com, path /
Let’s look for a settings file at
14
What normally happens.

21. We’ve got a request for http://www.example.com/
That’s from host www.example.com, path /
Let’s look for a settings file at
sites/www.example.com/settings.php
14
What normally happens.

22. We’ve got a request for http://www.example.com/
That’s from host www.example.com, path /
Let’s look for a settings file at
sites/www.example.com/settings.php
sites/example.com/settings.php
14
What normally happens.

23. We’ve got a request for http://www.example.com/
That’s from host www.example.com, path /
Let’s look for a settings file at
sites/www.example.com/settings.php
sites/example.com/settings.php
sites/com/settings.php
14
What normally happens.

24. We’ve got a request for http://www.example.com/
That’s from host www.example.com, path /
Let’s look for a settings file at
sites/www.example.com/settings.php
sites/example.com/settings.php
sites/com/settings.php
sites/default/settings.php
14
What normally happens.

25. http://www.example.com
http://banana.example.com
15
We’re talking about having multiple sites on ONE copy of Drupal.

26. $db_url = 'mysqli://jdoe:secret@localhost/banana';
$db_url = 'mysqli://moe:shhhh@localhost/www';
16
Now banana.example.com will get a site using the banana database; everything else gets the
www database.

27. $db_url = 'mysqli://jdoe:secret@localhost/banana';
banana
$db_url = 'mysqli://moe:shhhh@localhost/www';
16
Now banana.example.com will get a site using the banana database; everything else gets the
www database.

28. $db_url = 'mysqli://jdoe:secret@localhost/banana';
banana
example
$db_url = 'mysqli://moe:shhhh@localhost/www';
16
Now banana.example.com will get a site using the banana database; everything else gets the
www database.

29. $db_url = 'mysqli://jdoe:secret@localhost/banana';
banana
example
$db_url = 'mysqli://moe:shhhh@localhost/www';
16
Now banana.example.com will get a site using the banana database; everything else gets the
www database.

30. $db_url = 'mysqli://jdoe:secret@localhost/banana';
banana
example
$db_url = 'mysqli://moe:shhhh@localhost/www';
16
Now banana.example.com will get a site using the banana database; everything else gets the
www database.

31. Edge case
http://www.example.com/something
17
Need a symlink

32. http://banana.example.com/fanclub
18

33. CCK and Views
available for all sites
porcupine theme
available for all sites
19

34. 20

35. fivestar module
only available
on banana.example.com
20

36. fivestar module
only available
on banana.example.com
bananator module
only available
on banana.example.com
20

37. fivestar module
only available
on banana.example.com
bananator module
only available
on banana.example.com
gobananas theme
only available
on banana.example.com
20

38. 21
Each site has its own place to put uploaded files.

39. http://www.example.com/sites/www.example.com/files/
image.jpg
22
mod_rewrite can help make your URLs more friendly

40. http://www.example.com/sites/www.example.com/files/
image.jpg
RewriteRule ^files/(.*)$ /sites/%{HTTP_HOST}/files/$1 [L]
22
mod_rewrite can help make your URLs more friendly

41. http://www.example.com/sites/www.example.com/files/
image.jpg
RewriteRule ^files/(.*)$ /sites/%{HTTP_HOST}/files/$1 [L]
http://www.example.com/files/image.jpg
22
mod_rewrite can help make your URLs more friendly

42. Summary So Far
• Single codebase
• Everything in sites/all is shared: modules,
themes
• Site-specific modules and themes go in
sites/sitename/
• Each site has its own file uploads directory
23

43. Cron!
24

44. Updating Multisite
25

45. Updating a Drupal Site
example
26
The database contains content and most configuration settings.

46. Updating a Drupal Site
example
26
The database contains content and most configuration settings.

47. Updating a Drupal Site
example
26
The database contains content and most configuration settings.

48. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

49. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

50. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

51. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

52. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

53. Updating Multisite
banana
cherry
27
Running update.php once is not enough!

54. What is Multisite?
How Multisite Works
Sharing Information Between Sites
28

55. Table Prefixing
29
Prefixing originally for multiple Drupal sites on cheap hosting

56. Table Prefixing
29
Prefixing originally for multiple Drupal sites on cheap hosting

57. Table Prefixing
$db_prefix = 'zoinks_';
29
Prefixing originally for multiple Drupal sites on cheap hosting

58. $db_prefix = array(
'default' => 'main_',
'users' => 'shared_',
'sessions' => 'shared_',
'role' => 'shared_',
'authmap' => 'shared_',
);
30
settings.php

59. $db_prefix = array(
'default' => '',
'users' => 'shared.',
'sessions' => 'shared.',
'role' => 'shared.',
'authmap' => 'shared.',
);
shared.users
databasename.tablename
31
settings.php

60. access
actions example
actions_aid
authmap
...
32
What will happen with this arrangement? Nothing different! The location of the two tables has
just changed (users and authmap tables in the example database are unused).

61. users shared
authmap
access
actions example
actions_aid
authmap
...
32
What will happen with this arrangement? Nothing different! The location of the two tables has
just changed (users and authmap tables in the example database are unused).

62. users shared
authmap
access
actions example
actions_aid
authmap
...
32
What will happen with this arrangement? Nothing different! The location of the two tables has
just changed (users and authmap tables in the example database are unused).

63. access
actions banana
actions_aid
authmap
...
access
actions example
actions_aid
authmap
...
33
Still no change in behavior!

64. users shared
authmap
access
actions banana
actions_aid
authmap
...
access
actions example
actions_aid
authmap
...
33
Still no change in behavior!

65. users shared
authmap
access
actions banana
actions_aid
authmap
...
access
actions example
actions_aid
authmap
...
33
Still no change in behavior!

66. users shared
authmap
access
actions banana
actions_aid
authmap
...
access
actions example
actions_aid
authmap
...
33
Still no change in behavior!

67. “Logged in” means
• Cookie containing session ID
• Entry in sessions table containing session
ID
• Entry in users table
34

68. users shared
authmap
$user
sessions banana
role
35

69. users shared
authmap
$user
sessions banana
role
sessions example
role
36

70. Share user, authmap
Separate login on each site
Simultaneous logins!
User record shared
Roles are not shared
Role assignments are not shared
37

71. Share user, authmap
Separate login on each site
Simultaneous logins!
User record shared
Roles are not shared
Role assignments are not shared
37

72. Shared Logins
38

73. users
authmap shared
sessions
$user
role banana
39

74. users
authmap shared
sessions
$user
$db_prefix = array( role banana
'default' => '',
'users' => 'shared.',
'authmap' => 'shared.',
'sessions' => 'shared.',
);
39

75. What happens?
40

76. What happens?
• Log into http://banana.example.com
40

77. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
40

78. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
• We’re not logged in!
40

79. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
• We’re not logged in!
• Huh?
40

80. What’s wrong with this picture?
SESS0787a3dbcceb3bde85599fd17a876fa8de:
d977085b070ee1f8def0fa7c2fb26ada
SESS2611eb8d937302f9383947cd79a86d6888:
26bd9e318d607b0581696431bcfb93b1
41

81. $cookie_domain = ‘example.com’
42

82. What happens?
43

83. What happens?
• Log into http://banana.example.com
43

84. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
43

85. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
• We’re already logged in!
43

86. What happens?
• Log into http://banana.example.com
• Go to http://www.example.com
• We’re already logged in!
• Yay!
43

87. user, authmap, sessions +
$cookie_domain
One login for all sites
User record shared
Roles are not shared
Role assignments are not shared
44

88. users
authmap shared
sessions
role
$user
banana
45

89. users
authmap shared
sessions
role
$user
$db_prefix = array( banana
'default' => '',
'users' => 'shared.',
'authmap' => 'shared.',
'sessions' => 'shared.',
'role' => 'shared.',
);
45

90. 46

91. user, authmap, sessions, role +
$cookie_domain
One login for all sites
User record shared
Role names/ids shared
Role assignments are not shared
47

92. users
authmap
sessions shared
role
users_roles
$user
banana
48

93. users
authmap
sessions shared
role
users_roles
$user
$db_prefix = array(
'default' => '', banana
'users' => 'shared.',
'authmap' => 'shared.',
'sessions' => 'shared.',
'role' => 'shared.',
'users_roles' => 'shared.',
);
48

94. user, authmap, sessions, role,
users_roles + $cookie_domain
One login for all sites
User record shared
Role names/ids shared
Role assignments shared
49

95. User Role
Login Role
record assignment
user
+ sessions *
+ role
+
users_role
50

96. Caution!
51

97. Caution!
• Table contention
51

98. Caution!
• Table contention
• Database updates
51

99. Caution!
• Table contention
• Database updates
• Don’t share role
assignments and not
role IDs!
51

100. Caution!
• Table contention
• Database updates
• Don’t share role
assignments and not
role IDs!
• Think it out using
stories!
51

101. What is Multisite?
How Multisite Works
Sharing Information Between Sites
52