Ubuntu Manpage: debconf.conf - debconf configuration file

NAME

       debconf.conf - debconf configuration file

DESCRIPTION

       Debconf  is a configuration system for Debian packages. /etc/debconf.conf and ~/.debconfrc
       are configuration files debconf uses to determine which databases  it  should  use.  These
       databases  are  used  for  storing  two types of information; dynamic config data the user
       enters into it, and static template data. Debconf offers a flexible,  extensible  database
       backend.  New  drivers can be created with a minimum of effort, and sets of drivers can be
       combined in various ways.

SYNOPSIS

         # This is a sample config file that is
         # sufficient to use debconf.
         Config: configdb
         Templates: templatedb

         Name: configdb
         Driver: File
         Filename: /var/cache/debconf/config.dat

         Name: templatedb
         Driver: File
         Mode: 644
         Filename: /var/cache/debconf/templates.dat

FILE FORMAT

The format of this file is a series of stanzas, each separated by at least one wholly
blank line. Comment lines beginning with a "#" character are ignored.

The first stanza of the file is special, is used to configure debconf as a whole. Two
fields are required to be in this first stanza:

Config Specifies the name of the database from which to load config data.

Templates
Specifies the name of the database to use for the template cache.

Additional fields that can be used include:

Frontend
The frontend Debconf should use, overriding any frontend set in the debconf
database.

Priority
The priority Debconf should use, overriding any priority set in the debconf
database.

Admin-Email
The email address Debconf should send mail to if it needs to make sure that
the admin has seen an important message. Defaults to "root", but can be set
to any valid email address to send the mail there. If you prefer to never
have debconf send you mail, specify a blank address. This can be overridden
on the fly with the DEBCONF_ADMIN_EMAIL environment variable.

Debug If set, this will cause debconf to output debugging information to standard
error. The value it is set to can be something like "user", "developer",
"db", or a regular expression. Typically, rather than setting it permanently
in a config file, you will only want to temporarily turn on debugging, and
the DEBCONF_DEBUG environment variable can be set instead to accomplish
that.

NoWarnings
If set, this will make debconf not display warnings about various things.
This can be overridden on the fly with the DEBCONF_NOWARNINGS environment
variable.

Log Makes debconf log debugging information as it runs, to the syslog. The value
it is set to controls that is logged. See Debug, above for an explanation of
the values that can be set to control what is logged.

Terse If set to "true", makes some debconf frontends use a special terse display
mode that outputs as little as possible. Defaults to false. Terse mode may
be temporarily set via the DEBCONF_TERSE environment variable.

For example, the first stanza of a file might look like this:
Config: configdb
Templates: templatedb

Each remaining stanza in the file sets up a database. A database stanza begins by naming
the database:
Name: configdb

Then it indicates what database driver should be used for this database. See DRIVERS,
below, for information about what drivers are available.
Driver: File

You can indicate that the database is not essential to the proper functioning of debconf
by saying it is not required. This will make debconf muddle on if the database fails for
some reason.
Required: false

You can mark any database as readonly and debconf will not write anything to it.
Readonly: true

You can also limit what types of data can go into the database with Accept- and Reject-
lines; see ACCESS CONTROLS, below.

The remainder of each database stanza is used to provide configuration specific to that
driver. For example, the Text driver needs to know a directory to put the database in, so
you might say:
Filename: /var/cache/debconf/config.dat

DRIVERS

A number of drivers are available, and more can be written with little difficulty. Drivers
come in two general types. First there are real drivers -- drivers that actually access
and store data in some kind of database, which might be on the local filesystem, or on a
remote system. Then there are meta-drivers that combine other drivers together to form
more interesting systems. Let's start with the former.

File
This database driver allows debconf to store a whole database in a single flat text
file. This makes it easy to archive, transfer between machines, and edit. It is one
of the more compact database formats in terms of disk space used. It is also one of
the slowest.

On the downside, the entire file has to be read in each time debconf starts up, and
saving it is also slow.

The following things are configurable for this driver.

Filename
The file to use as the database. This is a required field.

Mode The permissions to create the file with if it does not exist.
Defaults to 600, since the file could contain passwords in some
circumstances.

Format The format of the file. See FORMATS below. Defaults to using a
rfc-822 like format.

Backup Whether a backup should be made of the old file before changing it.
Defaults to true.

As example stanza setting up a database using this driver:

Name: mydb
Driver: File
Filename: /var/cache/debconf/mydb.dat

DirTree
This database driver allows debconf to store data in a hierarchical directory
structure. The names of the various debconf templates and questions are used as-is
to form directories with files in them. This format for the database is the easiest
to browse and fiddle with by hand. It has very good load and save speeds. It also
typically occupies the most space, since a lot of small files and subdirectories do
take up some additional room.

The following things are configurable for this driver.

Directory
The directory to put the files in. Required.

Extension
An extension to add to the names of files. Must be set to a non-empty
string; defaults to ".dat"

Format The format of the file. See FORMATS below. Defaults to using a
rfc-822 like format.

Backup Whether a backup should be made of the old file before changing it.
Defaults to true.

As example stanza setting up a database using this driver:

Name: mydb
Driver: DirTree
Directory: /var/cache/debconf/mydb
Extension: .txt

PackageDir
This database driver is a compromise between the File and DirTree databases. It
uses a directory, in which there is (approximately) one file per package that uses
debconf. This is fairly fast, while using little more room than the File database
driver.

This driver is configurable in the same ways as is the DirTree driver, plus:

Mode The permissions to create files with. Defaults to 600, since the files could
contain passwords in some circumstances.

As example stanza setting up a database using this driver:

Name: mydb
Driver: PackageDir
Directory: /var/cache/debconf/mydb

LDAP
WARNING: This database driver is currently experimental. Use with caution.

This database driver accesses a LDAP directory for debconf configuration data. Due
to the nature of the beast, LDAP directories should typically be accessed in read-
only mode. This is because multiple accesses can take place, and it's generally
better for data consistency if nobody tries to modify the data while this is
happening. Of course, write access is supported for those cases where you do want
to update the config data in the directory.

For information about setting up a LDAP server for debconf, read
/usr/share/doc/debconf-doc/README.LDAP (from the debconf-doc package).

To use this database driver, you must have the libnet-ldap-perl package installed.
Debconf suggests that package, but does not depend on it.

Please carefully consider the security implications of using a remote debconf
database. Unless you trust the source, and you trust the intervening network, it is
not a very safe thing to do.

The following things are configurable for this driver.

server The host name or IP address of an LDAP server to connect to.

port The port on which to connect to the LDAP server. If none is given,
the default port is used.

basedn The DN under which all config items will be stored. Each config item
will be assumed to live in a DN of cn=<item name>,<Base DN>. If this
structure is not followed, all bets are off.

binddn The DN to bind to the directory as. Anonymous bind will be used if
none is specified.

bindpasswd
The password to use in an authenticated bind (used with binddn,
above). If not specified, anonymous bind will be used.

This option should not be used in the general case. Anonymous binding
should be sufficient most of the time for read-only access.
Specifying a bind DN and password should be reserved for the
occasional case where you wish to update the debconf configuration
data.

keybykey
Enable access to individual LDAP entries, instead of fetching them
all at once in the beginning. This is very useful if you want to
monitor your LDAP logs for specific debconf keys requested. In this
way, you could also write custom handling code on the LDAP server
part.

Note that when this option is enabled, the connection to the LDAP
server is kept active during the whole Debconf run. This is a little
different from the all-in-one behavior where two brief connections
are made to LDAP; in the beginning to retrieve all the entries, and
in the end to save eventual changes.

An example stanza setting up a database using this driver, assuming the remote
database is on example.com and can be accessed anonymously:

Name: ldapdb
Driver: LDAP
Readonly: true
Server: example.com
BaseDN: cn=debconf,dc=example,dc=com
KeyByKey: 0

Another example, this time the LDAP database is on localhost, and can be written
to:

Name: ldapdb
Driver: LDAP
Server: localhost
BaseDN: cn=debconf,dc=domain,dc=com
BindPasswd: secret
KeyByKey: 1

Pipe
This special-purpose database driver reads and writes the database from standard
input/output. It may be useful for people with special needs.

The following things are configurable for this driver.

Format The format to read and write. See FORMATS below. Defaults to using a
rfc-822 like format.

Infd File descriptor number to read from. Defaults to reading from stdin.
If set to "none", the database will not read any data on startup.

Outfd File descriptor number to write to. Defaults to writing to stdout. If
set to "none", the database will be thrown away on shutdown.

That's all of the real drivers, now moving on to meta-drivers..

Stack
This driver stacks up a number of other databases (of any type), and allows them to
be accessed as one. When debconf asks for a value, the first database on the stack
that contains the value returns it. If debconf writes something to the database,
the write normally goes to the first driver on the stack that has the item debconf
is modifying, and if none do, the new item is added to the first writable database
on the stack.

Things become more interesting if one of the databases on the stack is readonly.
Consider a stack of the databases foo, bar, and baz, where foo and baz are both
readonly. Debconf wants to change an item, and this item is only present in baz,
which is readonly. The stack driver is smart enough to realize that won't work, and
it will copy the item from baz to bar, and the write will take place in bar. Now
the item in baz is shadowed by the item in bar, and it will not longer be visible
to debconf.

This kind of thing is particularly useful if you want to point many systems at a
central, readonly database, while still allowing things to be overridden on each
system. When access controls are added to the picture, stacks allow you to do many
other interesting things, like redirect all passwords to one database while a
database underneath it handles everything else.

Only one piece of configuration is needed to set up a stack:

Stack This is where you specify a list of other databases, by name, to tell
it what makes up the stack.

For example:

Name: megadb
Driver: stack
Stack: passworddb, configdb, companydb

WARNING: The stack driver is not very well tested yet. Use at your own risk.

Backup
This driver passes all requests on to another database driver. But it also copies
all write requests to a backup database driver.

You must specify the following fields to set up this driver:

Db The database to read from and write to.

Backupdb
The name of the database to send copies of writes to.

For example:

Name: backup
Driver: Backup
Db: mydb
Backupdb: mybackupdb

Debug
This driver passes all requests on to another database driver, outputting verbose
debugging output about the request and the result.

You must specify the following fields to set up this driver:

Db The database to read from and write to.

ACCESS CONTROLS

       When you set up a database, you can also use some fields to specify access  controls.  You
       can  specify  that a database only accepts passwords, for example, or make a database only
       accept things with "foo" in their name.

       Readonly
              As was mentioned earlier, this access control, if set to "true", makes  a  database
              readonly. Debconf will read values from it, but will never write anything to it.

       Accept-Name
              The  text  in  this  field  is a perl-compatible regular expression that is matched
              against the names of items as they are requested from  the  database.  Only  if  an
              items  name  matches  the  regular  expression,  will the database allow debconf to
              access or modify it.

       Reject-Name
              Like Accept-Name, except any item name matching this  regular  expression  will  be
              rejected.

       Accept-Type
              Another regular expression, this matches against the type of the item that is being
              accessed. Only if the type matches the regex will access be granted.

       Reject-Type
              Like Accept-Type,  except  any  type  matching  this  regular  expression  will  be
              rejected.

FORMATS

       Some  of the database drivers use format modules to control the actual format in which the
       database is stored on disk. These formats are currently supported:

       822    This is a file format loosely based upon  the  rfc-822  format  for  email  message
              headers.  Similar  formats are used throughout Debian; in the dpkg status file, and
              so on.

EXAMPLE

       Here is a more complicated example of a debconf.conf file.

         # This stanza is used for general debconf setup.
         Config: stack
         Templates: templates
         Log: developer
         Debug: developer

         # This is my own local database.
         Name: mydb
         Driver: DirTree
         Directory: /var/cache/debconf/config

         # This is another database that I use to hold
         # only X server configuration.
         Name: X
         Driver: File
         Filename: /etc/X11/debconf.dat
         Mode: 644
         # It's sorta hard to work out what questions
         # belong to X; it should be using a deeper
         # tree structure so I could just match on ^X/
         # Oh well.
         Accept-Name: xserver|xfree86|xbase

         # This is our company's global, read-only
         # (for me!) debconf database.
         Name: company
         Driver: LDAP
         Server: debconf.foo.com
         BaseDN: cn=debconf,dc=foo,dc=com
         BindDN: uid=admin,dc=foo,dc=com
         BindPasswd: secret
         Readonly: true
         # I don't want any passwords that might be
         # floating around in there.
         Reject-Type: password
         # If this db is not accessible for whatever
         # reason, carry on anyway.
         Required: false

         # I use this database to hold
         # passwords safe and secure.
         Name: passwords
         Driver: File
         Filename: /etc/debconf/passwords
         Mode: 600
         Accept-Type: password

         # Let's put them all together
         # in a database stack.
         Name: stack
         Driver: Stack
         Stack: passwords, X, mydb, company
         # So, all passwords go to the password database.
         # Most X configuration stuff goes to the X
         # database, and anything else goes to my main
         # database. Values are looked up in each of those
         # in turn, and if none has a particular value, it
         # is looked up in the company-wide LDAP database
         # (unless it's a password).

         # A database is also used to hold templates. We
         # don't need to make this as fancy.
         Name: templates
         Driver: File
         Mode: 644
         Format: 822
         Filename: /var/cache/debconf/templates

NOTES

       If you use something like ${HOME} in this file, it will be replaced with the value of  the
       named environment variable.

       Environment  variables  can  also  be  used  to  override  the  databases  on the fly, see
       debconf(7)

       The field names (the part of the line before the colon) is case-insensitive.  The  values,
       though, are case sensitive.

PLANNED ENHANCEMENTS

       More  drivers and formats. Some ideas include: A SQL driver, with the capability to access
       a remote database.  A DHCP driver, that makes available some special things like hostname,
       IP  address,  and  DNS  servers.  A driver that pulls values out of public DNS records TXT
       fields.  A format that is compatible with the output of  cdebconf.   An  override  driver,
       which can override the value field or flags of all requests that pass through it.

FILES

       /etc/debconf.conf

       ~/.debconfrc

AUTHOR

       Joey Hess <joeyh@debian.org>

                                                                                  DEBCONF.CONF(5)

NAME

DESCRIPTION

SYNOPSIS

FILE FORMAT

DRIVERS

ACCESS CONTROLS

FORMATS

EXAMPLE

NOTES

PLANNED ENHANCEMENTS

FILES

SEE ALSO

AUTHOR