Cloning a Debian server - Revision history

Christensen: /* Cloning the configuration */

2006-02-21T14:46:31Z

Cloning the configuration

Christensen: /* Cloning the configuration */

2006-02-20T18:55:04Z

Cloning the configuration

Christensen: /* Installing packages */

2006-02-20T18:34:03Z

Installing packages

Christensen at 17:39, 20 February 2006

2006-02-20T17:39:29Z

Christensen at 17:19, 20 February 2006

2006-02-20T17:19:39Z

Christensen at 14:40, 23 January 2006

2006-01-23T14:40:35Z

Christensen at 14:32, 23 January 2006

2006-01-23T14:32:50Z

New page

Cloning a server an be necessary for various reasons, e.g. due to hardware failures and upgrades as well as after hacker attacks. Notice that in order to clone a server using the method described below, you need access to the server that you want to clone. Hence, it is a good idea to take the steps described below BEFORE a machine crashes or is compromised.

== Installing packages ==
On the server that you wish to clone, you have get a list of installed packages:

<pre>
$ dpkg --get-selections > packages_selected.txt
</pre>

The machine on which you want to install the server clone has to be up and ready to receive a Debian fresh installation. Find a [http://www.debian.org]] Debian installation image and install a ''minimal system''. Copy the file containing the package selections (packages_selected.txt) to the newly installed system and:

<pre>
$ cat packages_selected.txt | dpkg --set-selections
</pre>

This will selected the packages that were selected on the server you want to clone. In order to actually install the packages run:

<pre>
$ dselect
</pre>

And choose "Install". Don't worry too much about the various configuration options as you are likely going to overwrite during the configuation cloning.

== Cloning the configuration ==

@@ Line 56: / Line 56: @@
 </pre>
-For more on how to use cfengine's ''editfiles'' features, see:
+For more on how to use cfengine's ''editfiles'' features, see: [http://linux-green.lanl.gov/gnu/Manuals/cfengine-1.6.3/html_node/cfengine-Reference_65.html Cfengine Manual]
 == User files ==

← Older revision		Revision as of 18:55, 20 February 2006
Line 47:		Line 47:

	== Cloning the configuration ==		== Cloning the configuration ==
		+	cfengine is used to maintain the configuration files for the servers. The reason behind this is that cfengine allows for configuration file changes to be idempotent, flexible and all changes, including removal/out commeting of lines, additions etc. can be done neatly from within a single, high-level script. Thus, all changes done to a configuration file is done through a cfengine script.
		+
		+	Cfengine does in fact do a lot of other things too, but all we use are the "file edit" features.
		+
		+	If the cfengine package is not installed, then:
		+	<pre>
		+	$ apt-get install cfengine
		+	</pre>
		+
		+	For more on how to use cfengine's ''editfiles'' features, see:
		+
		+	[http://linux-green.lanl.gov/gnu/Manuals/cfengine-1.6.3/html_node/cfengine-Reference_65.html Cfengine Manual]
		+
		+	And for a couple of small useful examples, see:
		+
		+	[http://cfwiki.org/cfwiki/index.php/Editfiles_Examples Cfwiki]

	== User files ==		== User files ==

@@ Line 44: / Line 44: @@
 </pre>
-And choose "Install". Before confirming the install, check that you do not remove any ''critical'' packages (hence, scroll up and read the "To be REMOVED section). Don't worry too much about the various configuration options as you are likely going to overwrite during the configuation cloning.
+And choose "Install". Before confirming the install, check that you do not remove any ''critical'' packages (hence, scroll up and read the "To be REMOVED" section). Don't worry too much about the various configuration options as you are likely going to overwrite during the configuation cloning.
 == Cloning the configuration ==

@@ Line 22: / Line 22: @@
 Now, change all occurances of "install" to "deinstall" on packages_minimal.txt, except hardware specific packages (e.g. for usb keyboards, network devices etc.).
 Copy the file containing the package selections for the server (packages_server.txt) to the newly installed system and:
@@ Line 35: / Line 44: @@
 </pre>
-And choose "Install". Don't worry too much about the various configuration options as you are likely going to overwrite during the configuation cloning.
+And choose "Install". Before confirming the install, check that you do not remove any ''critical'' packages (hence, scroll up and read the "To be REMOVED section). Don't worry too much about the various configuration options as you are likely going to overwrite during the configuation cloning.
 == Cloning the configuration ==

@@ Line 12: / Line 12: @@
 <pre>
-$ dpkg --get-selections > packages_selected.txt
+$ dpkg --get-selections > packages_server.txt
 </pre>
-The machine on which you want to install the server clone has to be up and ready to receive a Debian fresh installation. Find a [http://www.debian.org]] Debian installation image and install a ''minimal system''. Copy the file containing the package selections (packages_selected.txt) to the newly installed system and:
+The machine on which you want to install the server clone has to be up and ready to receive a Debian fresh installation. Find a [http://www.debian.org  Debian installation image] and install a ''minimal system''. Get a list of all the packages installed on the new minimal system:
 <pre>
-$ cat packages_selected.txt | dpkg --set-selections
+$ dpkg --get-selections > packages_minimal.txt
 </pre>
 <pre>

@@ Line 1: / Line 1: @@
 Cloning a server an be necessary for various reasons, e.g. due to hardware failures and upgrades as well as after hacker attacks. Notice that in order to clone a server using the method described below, you need access to the server that you want to clone. Hence, it is a good idea to take the steps described below BEFORE a machine crashes or is compromised.
 == Installing packages ==
@@ Line 23: / Line 30: @@
 == Cloning the configuration ==