Performances

LemonLDAP::NG is designed for high performance, both in throughput and response time. Indeed, it can use Apache2 threads capabilities but since Apache version 2.4, mpm_worker seems to break mod_perl. So to increase performances, prefer using Nginx.

Built-in

Cache system

LLNG uses different cache systems to avoid querying to many the databases:

Lifetime in memory Lifetime in Local-Cache (file) DB
Parameter Default Parameter Default
Configuration checkTime 10 minutes Until "reload" order
Session handlerInternalCache 15 seconds default_expires_in(*) 10 minutes

(*): Manager >> General parameters >> Sessions >> Sessions storage >> Cache module options

Configuration and sessions are first looked up in-memory, then in the cache file, and then in their backing store. This means that after a configuration reload (using Manager), you have to wait for checkTime before you can see your changes.

Global performance

By default, Linux does not use DNS cache and LemonLDAP::NG portal request DNS for each connexions on LDAP or DB. Under heavy loads, that can generated hundred of DNS queries and many errors on LDAP connexions (timed out) from IO::Socket.

To bypass this, you can:

  • Use IP in configuration to avoid DNS resolution
  • Install a DNS cache like nscd, dnsmasq or unbound

Cron optimization (or systemd timers)

LLNG installs its cron files without knowing how many servers are installed. You should optimize this to launch:

  • purgeCentralCache: only 1 time every 10 minutes for the whole system (or more)
  • purgeLocalCache: ~ 1 time per hour on each server

Handler performance

For Nginx, you can use another auth server instead of llng-fastcgi-server. See: Advanced PSGI usage.

To increase handler performance, you can disable "Sessions activity timeout" to prevent it from writing to the session database.

Handlers check rights and calculate headers for each HTTP hit. So to improve performances, avoid too complex rules by using macros, groups or local macros.

Macros and groups

Macros and groups are calculated during authentication process by the portal:

  • macros are used to extend (or rewrite) exported variables. A macro is stored as attributes: it can contain boolean results or any string
  • macros can also be used to import environment variables (these variables are in CGI format). Example: $ENV{HTTP_COOKIE}
  • groups are stored as space-separated strings in the special attribute "groups": it contains the names of groups whose rules were returned true for the current user
  • You can also get groups in $hGroups which is a Hash Reference of this form:
$hGroups = {
          'group3' => {
                        'description' => [
                                           'Service 3',
                                           'Service 3 TEST'
                                         ],
                        'cn' => [
                                  'group3'
                                ],
                        'name' => 'group3'
                      },
          'admin' => {
                       'name' => 'admin'
                     }
        }

Example for macros:

# boolean macro
isAdmin -> $uid eq 'foo' or $uid eq 'bar'
# other macro 
displayName -> $givenName." ".$surName
 
# Use a boolean macro in a rule
^/admin -> $isAdmin
# Use a string macro in a HTTP header
Display-Name -> $displayName

Example for groups:

# group
admin -> $uid eq 'foo' or $uid eq 'bar'
 
# Use a group in a rule
^/admin -> $groups =~ /\badmin\b/
 
# Or with hGroups
^/admin -> defined $hGroups->{'admin'}
Groups are computed after macros, so a group rule may involve a macro value.
Macros and groups are computed in alphanumeric order, that is, in the order they are displayed in the manager. For example, macro "macro1" will be computed before macro "macro2": so, expression of macro2 may involve value of macro1. As same for groups: a group rule may involve another, previously computed group.

Local macros

Macros and groups are stored in session database. Local macros is a special feature of handler that permit one to have macros useable localy only. Those macros are calculated only at the first usage and stored in the local session cache (only for this server) and only if the user access to the related applications. This avoid to have to many datas stored.

# rule
admin -> $admin ||= ($uid eq 'foo' or $uid eq 'bar')
# header
Display-Name -> $displayName ||= $givenName." ".$surName
Note that this feature is interesting only for the Lemonldap::NG systems protecting a high number of applications

Portal performances

General performances

The portal is the biggest component of Lemonldap::NG. Since version 2.0, portal runs under FastCGI and has been rewritten using plugins, so performance is increased in comparison to earlier versions. You just have to disable unused plugins:

  • disable unused issuer modules
  • disable notifications if not used
  • ...

By default it uses local storage to store its tokens. If you have more than 1 portal and if your load-balancer doesn't keep state, you have to disable this to use the global session storage (General parameters » portal Parameters » Advanced Parameters » Forms). Note that this will decrease performances.

In production environment for network performance, prefer using minified versions of javascript and css libs: use make install PROD=yes. This is done by default in RPM/DEB packages.

Apache::Session performances

Lemonldap::NG handlers use a local cache to store sessions (for 10 minutes). So Apache::Session module is not a problem for handlers. But it can be a bottleneck for the portal:

  1. When you use the multiple sessions restriction parameters, sessions are parsed for each authentication unless you use an Apache::Session::Browseable module.
  2. Since MySQL does not have always transaction feature, Apache::Session::MySQL has been designed to use MySQL locks. Since MySQL performances are very bad using this, if you want to store sessions in a MySQL database, prefer one of the following
Since 1.9.6, LLNG portal and handler check if session is valid at each access, so purgeCentralCache cron no longer needs to be launched every 10 minutes: one or two times per day is enough.

Replace MySQL by Apache::Session::Flex

In "Apache::Session module" field, set "Apache::Session::Flex" and use the following parameters:

Store      -> MySQL
Lock       -> Null
Generate   -> MD5
Serialize  -> Storable
DataSource -> dbi:mysql:sessions;host=...
UserName   -> ...
Password   -> ...
Since version 1.90 of Apache::Session, you can use Apache::Session::MySQL::NoLock instead

Use Apache::Session::Browseable

Apache::Session::Browseable is a wrapper for other Apache::Session modules that add the capability to manage indexes. Prefer versions ≥ 1.2.5 for better performances in DB cleaning. To use it (with PostgreSQL for example), choose "Apache::Session::Browseable::Postgres" as "Apache::Session module" and use the following parameters:

DataSource -> dbi:Pg:database=sessions;host=...
UserName   -> user
Password   -> password
Index      -> ipAddr uid

Note that Apache::Session::Browseable::MySQL doesn't use MySQL locks.

Look at Browseable session backend to known which index to choose.

Some Apache::Session module are not fully usable by Lemonldap::NG such as Apache::Session::Memcached since these modules do not offer capability to browse sessions. They does not allow one to use sessions explorer neither manage one-off sessions.

Performance test

A Apache::Session::Browseable::Redis has been created, it is the fastest (except for session explorer, defeated by Apache::Session::Browseable::DBI/LDAP])

This test isn't an "only-backend" test but embedded some LLNG methods, so real differences between engines are mitigate here.

Backend Portal and handlers Session explorer and one-off sessions
Name Configuration Insert 1000 Search 1 Purge 500 Parse all Search by substring Search by UID
Apache::Session::Browseable::LDAP mdb 159.66 0.0120 49.22 0.1110 0.0076 0.0050
Apache::Session::MySQL No lock 87.20 0.0039 23.14 0.0281 0.0252 0.0235
Apache::Session::Browseable::MySQL 91.79 0.0039 0.139 (1) 0.0272 0.0036 0.0026
Apache::Session::Browseable::MySQLJSON 86.06 0.0145 0.151 (2) 0.0104 0.0137 0.0038
Apache::Session::Postgres 18.31 0.0095 13.40 0.0323 0.0277 0.0264
Apache::Session::Postgres Unlogged table 9.16 0.0095 7.91 0.0318 0.0270 0.0254
Apache::Session::Browseable::Postgres Unlogged table with indexes 9.24 0.0094 0.103 (1) 0.0301 0.0036 0.0028
Apache::Session::Browseable::PgJSON Unlogged table, json field 9.25 0.0091 0.108 (1) 0.0247 0.0035 0.0029
Apache::Session::Browseable::PgJSON Unlogged table, jsonb field 9.25 0.0091 0.105 (1) 0.0126 0.0034 0.0029
Apache::Session::Browseable::PgHstore Unlogged table, hstore field 9.62 0.0111 0.105 (1) 0.0125 0.0033 0.0029
Apache::Session::Redis 2.13 0.0033 1.158 0.0623 0.0570 0.0550
Apache::Session::Browseable::Redis 2.36 0.0033 1.154 0.0643 0.1048 0.0024
The source of this test is available in sources: e2e-tests/sbperf.pl
  • (1) : "purge" test is done with Apache::Session::Browseable-1.2.5 and LLG-2.0. Earlier results are not so good.
  • (2) : "purge" test is done with Apache::Session::Browseable-1.2.6 and LLG-2.0.

Analysis:

  • LDAP servers are "write-once-read-many", so write performances are very bad. Don't use this on heavy load if "Session activity timeout" is enabled (if set, handler "write" sessions)
  • MySQL/MariaDB is better to read than to write. Prefer PostgreSQL if you use "Session activity timeout"
  • Logged tables decrease a lot insert performances with PostgreSQL, so use unlogged tables for sessions except for persistent sessions
  • Redis is the best for main usage
  • Browseable::Postgres/PgHstore/PgJSON are the best SQL solutions on average

LDAP performances

LDAP server can slow you down when you use LDAP groups retrieval. You can avoid this by setting "memberOf" fields in your LDAP scheme:

dn: uid=foo,dmdName=people,dc=example,dc=com
...
memberOf: cn=admin,dmdName=groups,dc=example,dc=com
memberOf: cn=su,dmdName=groups,dc=example,dc=com

So instead of using LDAP groups retrieval, you just have to store "memberOf" field in your exported variables. With OpenLDAP, you can use the memberof overlay to do it automatically.

Don't forget to create an index on the field used to find users (uid by default)
To avoid having group dn stored in sessions datas, you can use a macro to rewrite memberOf:
  • Exported variables
ldapgroups -> memberOf

For now, ldapgroups contains "cn=admin,dmdName=groups,dc=example,dc=com cn=su,dmdName=groups,dc=example,dc=com"

  • A little macro:
ldapgroups -> join(" ",($ldapgroups =~ /cn=(.*?),/g))

Now ldapgroups contains "admin su"

NGINX performances

To increase launch by web browser, for example to load js, css, or fonts, Gzip compression can be activated.

Edit file /etc/nginx/mime.types Check those lines or add :

application/vnd.ms-fontobject    eot;
application/x-font-ttf           ttf;
application/font-woff            woff;
font/opentype                    ott;

Edit file /etc/nginx/nginx.conf

gzip on; # active la compression Gzip
gzip_disable "msie6"; 
 
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_min_length 128;
gzip_types text/plain text/css application/json application/javascript application/x-javascript text/xml application/xml application/rss+xml text/javascript application/vnd.ms-fontobject application/x-font-ttf font/opentype image/jpeg image/png image/svg+xml image/x-icon;

Restart NGINX and watch web-browser console.

Manager performances

Disable unused modules

In lemonldap-ng.ini, set only modules that you will use. By default, configuration, sessions explorer, notifications explorer and second factor are enabled. Example:

[manager]
enabledModules = conf, sessions

Use static HTML files

Once Manager is installed, browse enabled modules (configuration, sessions, notifications) and save the web pages respectively under manager.html, sessions.html and notifications.html in the DocumentRoot directory. Then replace this in Manager file of Apache configuration:

RewriteRule "^/$" "/psgi/manager-server.fcgi" [PT]
# DirectoryIndex manager.html
# RewriteCond "%{REQUEST_FILENAME}" "!\.html$"
RewriteCond "%{REQUEST_FILENAME}" "!^/(?:static|doc|lib).*"
RewriteRule "^/(.+)$" "/psgi/manager-server.fcgi/$1" [PT]

by:

# RewriteRule "^/$" "/psgi/manager-server.fcgi" [PT]
DirectoryIndex manager.html
RewriteCond "%{REQUEST_FILENAME}" "!\.html$"
RewriteCond "%{REQUEST_FILENAME}" "!^/(?:static|doc|lib).*"
RewriteRule "^/(.+)$" "/psgi/manager-server.fcgi/$1" [PT]

So manager HTML templates will be no more generated by Perl but directly given by the web server.