All user-modifiable configuration parameters on the SME Server are stored in the configuration database. These values are used to generate the system configuration files, such as those found in the /etc/ directory.
The configuration databases may be modified by various programs on the system, including the SME Server manager, the SME Server console, or scripts run from the command line by a system administrator.
Each entry in the database is either a simple key/value pair or a key and a collection of related property/value pairs.
Note: The section describes the general structure of the configuration database. The actual entries and properties are subject to change between releases.
Simple configuration database entries take the form of a key/value pair:
[root@gsxdev1 ~]# config show AccessType AccessType=dedicated [root@gsxdev1 ~]# config show ConsoleMode ConsoleMode=login [root@gsxdev1 ~]# config show TimeZone TimeZone=Australia/NSW
More complex entries consist of a key, a type, and a collection of property/value pairs:
[root@gsxdev1 ~]# config show atalk
atalk=service
MaxClients=20
status=enabled
[root@gsxdev1 ~]# config show dhcpd
dhcpd=service
end=192.168.1.250
start=192.168.1.65
status=disabledIn most cases, complex entries are used in preference to simple entries. The complex entries allow additional properties to be stored for an entry, which enhances the system's flexibility.
You can access configuration database entries from the command line using the config command, as shown above, or the db command. The config command provides a shorthand for accessing the configuration database. The following commands are equivalent:
[root@gsxdev1 ~]# config show LocalIP LocalIP=192.168.1.100 [root@gsxdev1 ~]# db configuration show LocalIP LocalIP=192.168.1.100
Note: The term configuration database is used both to refer to the "master" configuration database and to refer collectively to the set of configuration databases, which includes the individual accounts, networks, and configuration databases.
The db allows you to access all of the databases. For example to show the details of the admin entry from accounts
[root@gsxdev1 ~]# db accounts show admin
admin=system
EmailForward=local
FirstName=Local
ForwardAddress=
LastName=Administrator
Lockable=no
PasswordSet=yes
Removable=no
Shell=/sbin/e-smith/console
VPNClientAccess=noDocumentation for the db command is displayed if you run it without providing any arguments:
[root@gsxdev1 ~]# db
usage:
/sbin/e-smith/db dbfile keys
/sbin/e-smith/db dbfile print [key]
/sbin/e-smith/db dbfile show [key]
/sbin/e-smith/db dbfile get key
/sbin/e-smith/db dbfile set key type [prop1 val1] [prop2 val2] ...
/sbin/e-smith/db dbfile setdefault key type [prop1 val1] [prop2 val2] ...
/sbin/e-smith/db dbfile delete key
/sbin/e-smith/db dbfile printtype [key]
/sbin/e-smith/db dbfile gettype key
/sbin/e-smith/db dbfile settype key type
/sbin/e-smith/db dbfile printprop key [prop1] [prop2] [prop3] ...
/sbin/e-smith/db dbfile getprop key prop
/sbin/e-smith/db dbfile setprop key prop1 val1 [prop2 val2] [prop3 val3] ...
/sbin/e-smith/db dbfile delprop key prop1 [prop2] [prop3] ...You can also access configuration database entries programmatically using the
esmith::ConfigDB and related Perl modules, which are
abstractions for the esmith::DB module.
For example, we can retrieve and show the admin account details like this:
use esmith::AccountsDB;
my $db = esmith::AccountsDB->open or die "Couldn't open AccountsDB\n";
my $admin = $db->get("admin") or die "admin account missing from AccountsDB\n";
print $admin->show();This code fragment would display the same information as running the db accounts show admin command we saw previously.
admin
EmailForward = local
FirstName = Local
ForwardAddress =
LastName = Administrator
Lockable = no
PasswordSet = yes
Removable = no
Shell = /sbin/e-smith/console
VPNClientAccess = no
type = systemThe Perl API will be covered in more depth in the exercises later in this manual. For documentation on the API, log into the SME Server and browse the documentation using the perldoc command:
perldoc esmith::ConfigDB perldoc esmith::AccountsDB perldoc esmith::HostsDB perldoc esmith::NetworksDB perldoc esmith::DB
The configuration databases are initialized from files in the /etc/e-smith/db/ hierarchy. These files can perform one of three actions:
Create a database entry and set it to a default value, if the entry does not already exist.
Force a database entry to a specific value, regardless of its current setting.
Migrate an entry from a previous value to a new value.
This design allows each package to provide part of the system configuration, or migrate the system configuration values as required. Note that a single database property can only be "owned" by one package. Database initialization is run during system install, system upgrade and after new software has been installed.
If you examine the /etc/e-smith/db/configuration/ directory you will see three subdirectories: defaults/, force/ and migrate/ to match the three options above. A similar structure exists for each of the other databases. A new database can be created by populating a new directory tree under the /etc/e-smith/db/ directory.
[root@gsxdev1 db]# cd /etc/e-smith/db [root@gsxdev1 db]# ls accounts domains networks yum_installed backups hosts spamassassin yum_repositories configuration mailpatterns yum_available yum_updates [root@gsxdev1 db]# ls configuration/ defaults force migrate
Defaults files are simple text files. If the corresponding database key/property already exists, it is skipped. Otherwise, the key/property is created and the value loaded. For example, this file:
[root@gsxdev1 db]# cat configuration/defaults/sshd/status disabled
would create the sshd database entry if it doesn't already exist, create the status property for that entry, again if it doesn't already exist, and finally set the status property to disabled.
Force files are just like defaults files, except they overwrite the existing value. So, this file:
[root@gsxdev1 db]# cat configuration/force/sysconfig/ReleaseVersion 7.0rc2
would create the ReleaseVersion property of the sysconfig entry and unconditionally set its value to 7.0rc2
Migrate fragments are small pieces of Perl text which can be used to perform more complex migrations than is possible with defaults and force files. They would normally be used to replace database keys or properties with new names, or to adjust policy settings during an upgrade.
Each fragment is passed a reference to the current database in the
$DB variable. This variable is an instance of
the appropriate esmith::DB subclass, e.g.
esmith::AccountsDB when the accounts
database migrate fragments are being executed. This means that you
can use the methods of that subclass, for example
esmith::AccountsDB->users().
Here is an example of a migrate fragment, which replaces the outdated popd entry with the new name pop3:
{
my $popd = $DB->get("popd") or return;
my $pop3 = $DB->get("pop3") ||
$DB->new_record("pop3", { type => "service" });
$pop3->merge_props($popd->props);
$popd->delete;
}This fragment checks whether the database (the configuration database in this case) has a popd entry. If that entry does not exist, the migrate fragment returns immediately. If the popd entry exists, we need to convert it, so we retrieve the pop3 entry (or create it if it doesn't already exist). We then merge the properties from the popd entry into the pop3 entry and finally delete the popd entry.
If this migrate fragment is run again, it will return immediately as the popd entry has already been deleted.
Please be careful with migrate fragments. Although they should only modify entries within the current database, there are no restrictions placed on what they can do. The ability to open and even modify other databases may be required to perform a migration.
Migrate fragments must be safe to run multiple times. They should migrate the value when required and do nothing in other cases.
Migrate fragments should never call croak or die. This will cause the database migration to stop. If an error is detected, call carp or warn to note the error in the logs.
Migrate fragments should be owned by the package requiring the migration so that the migration only occurs when that package is installed.
Migrate fragments should be self-contained and ideally perform only one migration per fragment.
It is also possible to initialize and migrate database values in action scripts, but creation of migrate fragments is strongly preferred. Creating defaults is a simple matter of creating text files and migrate fragments require far less code than action scripts.
When a database is loaded:
migrate scripts are run first
then defaults are loaded
and finally any force files are loaded.
This order allows migration of old format entries to occur prior to loading of new default values. Remember, defaults will not change an existing database property.
The database is initialized during a number of events, including console-save, so a call to signal-event console-save will evaluate all of the database fragments.
Note: The console-save event is not a "reconfigure everything" event, and only changes items which can be configured from the text-mode console. It is convenient in this case as it performs database initialization and migration.
It is an SME Server requirement that all database entries and configuration files must be correctly configured after a "reconfiguration reboot". This is available from the console and server manager and performs the post-upgrade and reboot events. Packages should also provide links in other events (e.g. "email-update" for email related changes) to provide reconfiguration without the reboot.
The configuration databases should only be modified using the tools and APIs provided.
The order of the entries and the order of properties is undefined.
The keys and property names are currently treated in a case-sensitive manner, though this may change in the future. Do not create keys or property names which differ only by their case.
Underscores and hyphens are valid in key and property names, but should normally be avoided.
Do not "overload" an existing property with a new value. If the existing values do not meet your requirements, discuss your implementation with the developers. Values which are not known by the base may cause serious issues on upgrade. If the existing panels have three choices, do not invent new choices without enhancing the panel to support them.
The type pseudo-property is used internally and is reserved.
By convention, database keys are lower case, and property names are stored in mixed case. The type, status and access properties are exceptions to this convention.
The storage location and internals of the databases is subject to change.
The configuration databases are currently stored as pipe-delimited flat text files in the /home/e-smith/db/ directory.