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[3644] Review and edit of kea-admin part of the guide 

The edit also included a reorganisation of the sections.
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doc/guide/admin.xml
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<!ENTITY mdash "&#x2014;" >
]>
<chapter id="admin">
<title>Database administration</title>
<chapter id="admin">
<title>Kea Database Administration</title>
<section id="kea-database-version">
<title>Databases and Database Version Numbers</title>
<para>
Kea stores leases in one of several supported databases.
As future versions of Kea are released, the structure of those
databases will change. For example, Kea currently only stores
lease information: in the future, additional data - such as host
reservation details - will also be stored.
</para>
<para>
A given version of Kea expects a particular structure in
the database. It ensures this by checking the version of the
database it is using. Separate version numbers are maintained for
backend databases, independent of the version of Kea itself. It
is possible that the backend database version will stay the same
through several Kea revisions. Likewise, it is possible that the
version of backend database may go up several revisions during a
Kea upgrade. Versions for each database are independent, so an
increment in the MySQL database version does not imply an increment
in that of PostgreSQL.
</para>
<para>
Backend versions are specified in
a <replaceable>major.minor</replaceable> format. The minor
number is increased when there are backward compatibile changes
introduced. For example, ithe addition of a new index. It is
desirable, but not mandatory to to apply such a change; you
can run on older database version if you want to. (Although, in
the example given, running without the new index may be at the
expense of a performance penalty.) On the other hand, the major
number is increased when an incompatible change is introduced,
for example an extra column is added to a table. If you try to
run Kea software on a database that is too old (as signified by
mismatched backend major version number), Kea will refuse to run:
administrative action will be required to upgrade the database.
</para>
</section>
<section id="kea-admin">
<title>The kea-admin Tool</title>
<para>
To manage the databases, Kea provides the
<command>kea-admin</command> tool. It is able to initialize
a new database, check its version number, and perform a
database upgrade.
</para>
<para>
<command>kea-admin</command> takes two mandatory
parameters: <command>command</command> and
<command>backend</command>. Additional, non-mandatory options
may be specified. Currently supported commands are:
<itemizedlist>
<listitem>
<simpara>
<command>lease-init</command> &mdash;
Initializes a new lease database. Useful during first
Kea installation. The database is initialized to the
latest version supported by the version of the software.
</simpara>
</listitem>
<section id="kea-admin">
<title>kea-admin tool</title>
<listitem>
<simpara>
<command>lease-version</command> &mdash;
Reports the lease database version number. This is
not necessarily equal to the Kea version number as
each backend has its own versioning scheme.
</simpara>
</listitem>
<para>
Kea is able to store leases in one of several supported databases.
Additional types of data, like host reservation details, will
be supported in the near future. To manage those databases, a
tool called <command>kea-admin</command> was introduced. Currently
it is able to initialize new database, check its version
and perform database upgrade, if needed.
</para>
<listitem>
<simpara>
<command>lease-upgrade</command> &mdash;
Conducts a lease database upgrade. This is useful when
upgrading Kea.
</simpara>
</listitem>
</itemizedlist>
<para>
Kea mantains separate version numbering for its database backends. These
are independent of the Kea version. It is possible that the backend
revision will stay the same through several Kea revisions. Likewise, it
is possible that a backend may go up several times between two Kea
revisions, if there were several changes introduced that required database
schema change. Versions for each backend are independent, so a bump
in MySQL version does not imply bump in the Postgres version.
</para>
<command>backend</command> specifies the backend type. Currently
supported types are:
<para>
Backend versions are specified in major.minor format. Minor number is
increased when there are backward compatibile changes introduced. For
example, a new index is added. It is desirable, but not mandatory to
have it. You can run on older database version if you want to. On
the other hand, major number is increased when there's an incompatible
change introduced, for example an extra column is added. If you try
to run Kea software on a database that is too old (which is signified
by mismatched major backend version number), Kea will refuse to run
and an administrative action will be required to upgrade the database.
</para>
<para>
<command>kea-admin</command> takes two mandatory parameters:
<command>command</command> and <command>backend</command>. Additional,
non-mandatory options may be specified. Currently supported commands
are:
<itemizedlist>
<listitem>
<simpara>
<command>lease-init</command> &mdash;
Initializes a new lease database. Useful during first Kea
installation. The database is initialized to the latest version
supported by the version of the software.
</simpara>
</listitem>
<listitem>
<simpara>
<command>lease-version</command> &mdash;
Reports lease database version. This is not necessarily
equal to Kea version as each backend has its own versioning
scheme.
</simpara>
</listitem>
<listitem>
<simpara>
<command>lease-upgrade</command> &mdash;
Conducts lease database upgrade. This is useful when
migrating between old and new Kea versions.
</simpara>
</listitem>
</itemizedlist>
The <command>backend</command> specified backend type. Currently
allowed backends are: memfile, mysql and pgsql. There are additional
parameters that may be needed, depending on your setup and specific
operation: specify username, password and database name or the directory
where specific files are located. See appropriate manual page for
details (<command>man 8 kea-admin</command>).
</para>
<itemizedlist>
<listitem>
<simpara>
<command>memfile</command> &mdash; Lease information is
stored on disk in a text file.
</simpara>
</listitem>
</section>
<listitem>
<simpara>
<command>mysql</command> &mdash;
Lease information is stored in a MySQL relational
database.
</simpara>
</listitem>
<listitem>
<simpara>
<command>pgsql</command> &mdash;
Lease information is stored in a PostgreSQL relational
database.
</simpara>
</listitem>
</itemizedlist>
Additional parameters may be needed, depending on your setup
and specific operation: username, password and database name or
the directory where specific files are located. See appropriate
manual page for details (<command>man 8 kea-admin</command>).
</para>
</section>
<section>
<title>Supported Databases</title>
<section>
<title>memfile</title>
<para>There are no special initialization steps necessary for memfile
backend. During the first run, both <command>kea-dhcp4</command> and
<command>kea-dhcp6</command> will create an empty lease file, if it is not
present. Necessary disk write permission is required.
<para>
There are no special initialization steps necessary
for the memfile backend. During the first run, both
<command>kea-dhcp4</command> and <command>kea-dhcp6</command>
will create an empty lease file if one is not
present. Necessary disk write permission is required.
</para>
<!-- @todo: document lease file upgrades once they are implemented in kea-admin -->
</section>
<section>
<title>MySQL</title>
<para>
MySQL database must be properly set up if you want Kea to store lease
and other information in MySQL. This step can be safely skipped if you
chose to store the data in other backends, like memfile or PosgreSQL.
The MySQL database must be properly set up if you want Kea to
store information in MySQL. This section can be safely ignored
if you chose to store the data in other backends.
</para>
<section id="mysql-database-create">
<title>Initialize the MySQL Database using kea-admin</title>
<para>
There are two ways to initialize the database. The first one involves
running <command>kea-admin</command> tool, which attempts to automate
the process. It is convenient to use, but may not cover more complex
cases. The second alternative is to run all the commands
manually.
</para>
<section id="mysql-database-create">
<title>First Time Creation of Kea Database</title>
<para>
When <command>kea-admin</command> is told to initialize the database, it
assumes that the database and database user has been created. If not,
please follow the necessary instructions in <xref
linkend="mysql-database-create-manual" />.
</para>
<para>
To initialize new MySQL database using <command>kea-admin</command>, use the
following command:
<screen>$ <userinput>kea-admin lease-init mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
</screen>
<command>kea-admin</command> has rudimentary checks implemented. It will
refuse to initialize a database that has any existing tables. If you want
to start from scratch, you must remove existing data manually. This process
is left manual on purpose to avoid mistakes that could not be undone.
</para>
<para>
If you are setting the MySQL database for the first time,
you need to create the database area within MySQL and set up
the MySQL user ID under which Kea will access the database.
This needs to be done manually: <command>kea-admin</command>
is not able to do this for you.
</para>
</section>
<para>
To create the database:
<section id="mysql-upgrade">
<title>Upgrading MySQL database from earlier Kea versions</title>
<orderedlist>
<listitem>
<para>
Log into MySQL as "root":
<screen>
$ <userinput>mysql -u root -p</userinput>
Enter password:
mysql>
</screen>
</para>
</listitem>
<para>Sometime a new Kea version may use newer database schema and there may
be a need to upgrade existing database. This can be done using <command>kea-admin</command>.
It is possible to check existing database version:
<screen>$ <userinput>kea-admin lease-version mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
<listitem>
<para>
Create the MySQL database:
<screen>
mysql> <userinput>CREATE DATABASE <replaceable>database-name</replaceable>;</userinput>
</screen>
See <xref linkend="kea-admin"/> for a discussion about versioning.</para>
<para>It may be required to run database upgrade. This process is designed
to not discard any data, but depending on the nature of the changes, it
may be impossible to downgrade to earlier Kea version. Please back up your
database if you consider reverting to an earlier Kea version. To conduct
an upgrade, the following command should be used:
<screen>$ <userinput>kea-admin lease-upgrade mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
(<replaceable>database-name</replaceable> is the name
you have chosen for the database.)
</para>
</listitem>
<listitem>
<para>
Create the user under which Kea will access the database
(and give it a password), then grant it access to the
database tables:
<screen>
mysql> <userinput>CREATE USER '<replaceable>user-name</replaceable>'@'localhost' IDENTIFIED BY '<replaceable>password</replaceable>';</userinput>
mysql> <userinput>GRANT ALL ON <replaceable>database-name</replaceable>.* TO '<replaceable>user-name</replaceable>'@'localhost';</userinput>
</screen>
</para>
(<replaceable>user-name</replaceable> and
<replaceable>password</replaceable> are the user ID
and password you are using to allow Keas access to the
MySQL instance. All apostrophes in the command lines
above are required.)
</para>
</listitem>
<listitem>
<para>
At this point, you may elect to create the database
tables. (Alternatively, you can exit MySQL and create
the tables using the <command>kea-admin</command> tool,
as explained below.) To do this:
<screen>
mysql> <userinput>CONNECT <replaceable>database-name</replaceable>;</userinput>
mysql> <userinput>SOURCE <replaceable>path-to-kea</replaceable>/share/kea/dhcpdb_create.mysql</userinput>
</screen>
(<replaceable>path-to-kea</replaceable> is the
location where you installed Kea.)
</para>
</listitem>
<listitem>
<para>
Exit MySQL:
<screen>
mysql> <userinput>quit</userinput>
Bye
$
</screen>
</para>
</listitem>
</orderedlist>
</para>
</section>
<para>
If you elected not to create the tables in step 4, you can do
so now by running the <command>kea-admin</command> tool:
<screen>
$ <userinput>kea-admin lease-init mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
</screen>
(Do not do this if you did create the tables in step 4.)
<command>kea-admin</command> implements rudimentary checks:
it will refuse to initialize a database that contains any
existing tables. If you want to start from scratch, you
must remove all data manually. (This process is a manual
operation on purpose to avoid possibly irretrievable mistakes
by <command>kea-admin</command>.)
</para>
</section>
<section id="mysql-database-create-manual">
<title>Manually create the MySQL Database and the Kea User</title>
<section id="mysql-upgrade">
<title>Upgrading a MySQL Database from an Earlier Version of Kea</title>
<note>
<simpara>
This paragraph explains how to create and initialize MySQL database
manually. See <xref linkend="mysql-database-create" /> for a kea-admin,
a tool that automates most of those steps.
</simpara>
</note>
<para>
The first task is to create both the lease database and the user under
which the servers will access it. A number of steps are required:
Sometimes a new Kea version may use newer database schema, so
there will be a need to upgrade the existing database. This can
be done using the <command>kea-admin lease-upgrade</command>
command.
</para>
<para>
1. Log into MySQL as "root":
<screen>$ <userinput>mysql -u root -p</userinput>
Enter password:<userinput/>
:<userinput/>
mysql></screen>
To check the current version of the database, use the following command:
<screen>
$ <userinput>kea-admin lease-version mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
</screen>
(See <xref linkend="kea-database-version"/> for a discussion
about versioning.) If the version does not match the minimum
required for the new version of Kea (as described in the
release notes), the database needs to be upgraded.
</para>
<para>
2. Create the database:
<screen>mysql> <userinput>CREATE DATABASE <replaceable>database-name</replaceable>;</userinput></screen>
(<replaceable>database-name</replaceable> is the name you
have chosen for the database.)
</para>
<para>
3. Create the database tables by running the dhcpdb_create.mysql script supplied as part of Kea:
<screen>mysql> <userinput>CONNECT <replaceable>database-name</replaceable>;</userinput>
mysql> <userinput>SOURCE <replaceable>path-to-kea</replaceable>/share/kea/dhcpdb_create.mysql</userinput></screen>
</para>
<para>
4. Create the user under which Kea will access the database (and give it a password), then grant it access to the database tables:
<screen>mysql> <userinput>CREATE USER '<replaceable>user-name</replaceable>'@'localhost' IDENTIFIED BY '<replaceable>password</replaceable>';</userinput>
mysql> <userinput>GRANT ALL ON <replaceable>database-name</replaceable>.* TO '<replaceable>user-name</replaceable>'@'localhost';</userinput></screen>
Before upgrading, please make sure that the database is
backed up. The upgrade process does not discard any data but,
depending on the nature of the changes, it may be impossible
to subsequently downgrade to an earlier version. To perform
an upgrade, issue the following command:
<screen>
$ <userinput>kea-admin lease-upgrade mysql -u <replaceable>database-user</replaceable> -p <replaceable>database-password</replaceable> -d <replaceable>database-name</replaceable></userinput>
</screen>
</para>
<para>
5. Exit MySQL:
<screen>mysql> <userinput>quit</userinput>
Bye<userinput/>
$</screen>
</para>
</section>
</section>
</section> <!-- end of MySQL sections -->
<section>
<title>PostgreSQL</title>
<para>
PostgreSQL database must be properly set up if you want Kea to store lease
and other information in PostgreSQL. This step can be safely skipped if you
chose to store the data in other backends, like memfile or MySQL.
A PostgreSQL database must be set up if you want Kea to store
lease and other information in PostgreSQL. This step can be
safely ignored if you are using other database backends.
</para>
<section>
<title>Initialize the PostgreSQL Database using kea-admin</title>
<section id="pgsql-database-create">
<title>Manually Create the PostgreSQL Database and the Kea User</title>
<para>
Support for PostgreSQL in kea-admin is currently not implemented.
</para>
<!-- @todo: document PgSQL upgrade once they are implemented in kea-admin -->
</section>
The first task is to create both the lease database and the
user under which the servers will access it. A number of steps
are required:
<orderedlist>
<listitem>
<para>
Log into PostgreSQL as "root":
<screen>
$ <userinput>sudo -u postgres psql postgres</userinput>
Enter password:
postgres=#
</screen>
</para>
</listitem>
<section id="pgsql-database-create">
<title>Create PostgreSQL Database and Kea User</title>
<para>
The next task is to create both the lease database and the user under which the servers will
access it. A number of steps are required:
</para>
<para>
1. Log into PostgreSQL as "root":
<screen>$ <userinput>sudo -u postgres psql postgres</userinput>
Enter password:<userinput/>
:<userinput/>
postgres=#</screen>
</para>
<para>
2. Create the database:
<listitem>
<para>
Create the database:
<screen>
postgres=#<userinput> CREATE DATABASE <replaceable>database-name</replaceable>;</userinput>
CREATE DATABASE
postgres=#
</screen>
(<replaceable>database-name</replaceable> is the name you
have chosen for the database.)
</para>
<para>
3. Create the user under which Kea will access the database (and give it a password), then grant it access to the database:
<screen>postgres=#<userinput> CREATE USER <replaceable>user-name</replaceable> WITH PASSWORD '<replaceable>password</replaceable>';</userinput>
(<replaceable>database-name</replaceable> is the name
you have chosen for the database.)
</para>
</listitem>
<listitem>
<para>
Create the user under which Kea will access the database
(and give it a password), then grant it access to the
database:
<screen>
postgres=#<userinput> CREATE USER <replaceable>user-name</replaceable> WITH PASSWORD '<replaceable>password</replaceable>';</userinput>
CREATE ROLE
postgres=#
postgres=#<userinput> GRANT ALL PRIVILEGES ON DATABASE <replaceable>database-name</replaceable> TO <replaceable>user-name</replaceable>;</userinput>
GRANT
postgres=#
</screen>
</para>
<para>
4. Exit PostgreSQL:
<screen>postgres=# <userinput>\q</userinput>
Bye<userinput/>
$</screen>
</para>
<para>
5. Create the database tables using the new user's credentials and the dhcpdb_create.pgsql script supplied with Kea.
After entering the following command, you will be prompted for the new
user's password. When the command completes you will be returned to
the shell prompt. You should see output similar to following:
<screen>$ <userinput>psql -d <replaceable>database-name</replaceable> -U <replaceable>user-name</replaceable> -f <replaceable>path-to-kea</replaceable>/share/kea/dhcpdb_create.pgsql</userinput>
</para>
</listitem>
<listitem>
<para>
Exit PostgreSQL:
<screen>
postgres=# <userinput>\q</userinput>
Bye
$
</screen>
</para>
</listitem>
<listitem>
<para>
Create the database tables using the new user's
credentials and the dhcpdb_create.pgsql script supplied
with Kea. After entering the following command, you
will be prompted for the new user's password. When the
command completes you will be returned to the shell
prompt. You should see output similar to following:
<screen>
$ <userinput>psql -d <replaceable>database-name</replaceable> -U <replaceable>user-name</replaceable> -f <replaceable>path-to-kea</replaceable>/share/kea/dhcpdb_create.pgsql</userinput>
Password for user <replaceable>user-name</replaceable>:
CREATE TABLE
CREATE INDEX
......@@ -292,36 +382,56 @@ INSERT 0 1
COMMIT
$
</screen>
</para>
<para>
If instead you encounter an error like:
</para>
(<replaceable>path-to-kea</replaceable> is the location
where you installed Kea.)
</para>
<para>
If instead you encounter an error like:
<screen>
psql: FATAL: no pg_hba.conf entry for host "[local]", user "<replaceable>user-name</replaceable>", database "<replaceable>database-name</replaceable>", SSL off
</screen>
<para>
... you will need to alter the PostgreSQL configuration.
Kea uses password authentication when connecting to the database and must
have the appropriate entries added to PostgreSQL's pg_hba.conf file. This
file is normally located in the primary data directory for your PostgreSQL
server. The precise path may vary but the default location for PostgreSQL 9.3
on Centos 6.5 is:
<filename>/var/lib/pgsql/9.3/data/pg_hba.conf</filename>.
Assuming Kea is running on the same host as PostgreSQL, adding lines similar
to following should be sufficient to provide password-authenticated access to
Kea's database:
</para>
... you will need to alter the PostgreSQL configuration.
Kea uses password authentication when connecting to
the database and must have the appropriate entries
added to PostgreSQL's pg_hba.conf file. This file is
normally located in the primary data directory for your
PostgreSQL server. The precise path may vary but the
default location for PostgreSQL 9.3 on Centos 6.5 is:
<filename>/var/lib/pgsql/9.3/data/pg_hba.conf</filename>.
</para>
<para>
Assuming Kea is running on the same host as PostgreSQL,
adding lines similar to following should be sufficient to
provide password-authenticated access to Kea's database:
<screen>
local <replaceable>database-name</replaceable> <replaceable>user-name</replaceable> password
host <replaceable>database-name</replaceable> <replaceable>user-name</replaceable> 127.0.0.1/32 password
host <replaceable>database-name</replaceable> <replaceable>user-name</replaceable> ::1/128 password
</screen>
<para>
Please consult your PostgreSQL user manual before making these changes as they
may expose your other databases that you run on the same system.
</para>
</para>
<para>
Please consult your PostgreSQL user manual before making
these changes as they may expose your other databases
that you run on the same system.
</para>
</listitem>
</orderedlist>
</para>
</section>
</section> <!-- end of postgres sections -->
<section>
<title>Initialize the PostgreSQL Database Using kea-admin</title>