Wiki

Version 98 (Nikos Skalkotos, 03/11/2013 06:48 pm)

1 21 Constantinos Venetsanopoulos
h2. snf-image
2 21 Constantinos Venetsanopoulos
3 21 Constantinos Venetsanopoulos
!snf-image-logo.png!
4 1 Constantinos Venetsanopoulos
5 10 Vangelis Koukis
h2. Introduction - Features
6 10 Vangelis Koukis
7 54 Constantinos Venetsanopoulos
snf-image is a "Ganeti":http://code.google.com/p/ganeti/ OS Definition, primarily used by "Synnefo":https://code.grnet.gr/projects/synnefo .
8 2 Constantinos Venetsanopoulos
9 66 Constantinos Venetsanopoulos
It is rewritten from scratch and allows Ganeti to launch instances from predefined or untrusted custom Images. The whole process of deploying an Image onto the block device, as provided by Ganeti, is done in complete isolation from the physical host, enhancing robustness and security (currently supports only KVM based ganeti clusters).
10 1 Constantinos Venetsanopoulos
11 7 Vangelis Koukis
There are also additional hooks that can be enabled at image deployment. They allow for:
12 1 Constantinos Venetsanopoulos
13 7 Vangelis Koukis
 * changing the password of root or arbitrary users
14 7 Vangelis Koukis
 * injecting files at arbitrary locations inside the filesystem, e.g., SSH keys
15 7 Vangelis Koukis
 * setting a custom hostname
16 7 Vangelis Koukis
 * re-creating SSH host keys to ensure the image uses unique keys
17 1 Constantinos Venetsanopoulos
18 72 Nikos Skalkotos
snf-image has been used successfully to deploy many major Linux distributions (Debian, Ubuntu/Kubuntu, CentOS, Fedora), as well as Windows 2008 R2 & Windows Server 2012.
19 7 Vangelis Koukis
20 40 Constantinos Venetsanopoulos
The snf-image Ganeti OS Definition is released under [[Licence|GNU Generic Public Lisence version 2]].
21 35 Nikos Skalkotos
22 35 Nikos Skalkotos
h2. Ganeti OS Interface
23 35 Nikos Skalkotos
24 7 Vangelis Koukis
snf-image requires ganeti-os-interface v20 to operate.
25 7 Vangelis Koukis
It introduces the following OS parameters:
26 7 Vangelis Koukis
27 69 Nikos Skalkotos
 * @img_id@ (_required if @config_url@ is missing_): the URI used to identify the image (see [[Image IDs and Storage Back Ends|here]])
28 63 Constantinos Venetsanopoulos
 * @img_format@ (_required if @config_url@ is missing_): the image format type (see [[Image Format|here]])
29 63 Constantinos Venetsanopoulos
 * @img_passwd@ (_required if @config_url@ is missing_): the passwd to be injected inside the image
30 8 Vangelis Koukis
 * @img_properties@ (_optional_): additional image properties used to customize the image ([[Image_Format#Image-Properties|details]])
31 1 Constantinos Venetsanopoulos
 * @img_personality@ (_optional_): files to be injected into the image filesystem ([[Personality OS Parameter|details]]).
32 62 Constantinos Venetsanopoulos
 * @config_url@ (_optional_): the url to download configuration data from
33 1 Constantinos Venetsanopoulos
34 1 Constantinos Venetsanopoulos
h2. Architecture
35 8 Vangelis Koukis
36 96 Nikos Skalkotos
snf-image is split in two components: A part running on the Ganeti host, with full root privilege (@snf-image@ previously @snf-image-host@), and a part running inside an unprivileged, helper VM (@snf-image-helper@).
37 8 Vangelis Koukis
38 95 Nikos Skalkotos
h3. snf-image
39 8 Vangelis Koukis
40 8 Vangelis Koukis
This part implements the Ganeti OS interface. It extracts the Image onto the Ganeti-provided block device, using streaming block I/O (@dd@ with @oflag=direct@), then passes control to @snf-image-helper@ running inside a helper VM. The helper VM is created using KVM, runs as an unprivileged user, @nobody@ by default.
41 8 Vangelis Koukis
42 88 Nikos Skalkotos
There is no restriction on the distribution running inside the helper VM, as long as it executes the @snf-image-helper@ component automatically upon bootup. The @snf-image-update-helper@ script is provided with @snf-image-host@ to automate the creation of a helper VM image based on Debian Stable, using @multistrap@.
43 8 Vangelis Koukis
44 8 Vangelis Koukis
The @snf-image-helper@ component is spawned inside a specific hardware environment:
45 8 Vangelis Koukis
46 8 Vangelis Koukis
* The VM features a virtual floppy, containing an @ext2@ filesystem with all parameters needed for image customization.
47 8 Vangelis Koukis
* The hard disk of the VM being deployed is accessible as the first @virtio@ hard disk.
48 40 Constantinos Venetsanopoulos
* All kernel/console output is redirected to the first virtual serial console, and eventually finds its way into the OS definition log files that Ganeti maintains.
49 8 Vangelis Koukis
* The helper VM is expected to output "SUCCESS" to its second serial port if image customization was successful inside the VM.
50 8 Vangelis Koukis
  In any other case, execution of the helper VM or @snf-image-helper@ has failed.
51 8 Vangelis Koukis
* The helper VM is expected to shutdown automatically once it is done. Its execution is time-limited; if it has not terminated after a number of seconds, configurable via @/etc/default/snf-image@, it is sent a @SIGTERM@ and/or a @SIGKILL@.
52 8 Vangelis Koukis
53 8 Vangelis Koukis
KVM is currently a dependency for @snf-image@, meaning it is needed to spawn the helper VM. There is no restriction on the hypervisor used for the actual Ganeti instances. This is not a strict requirement; KVM could be replaced by @qemu@, doing full CPU virtualization without any kernel support for spawning the helper VM.
54 8 Vangelis Koukis
55 8 Vangelis Koukis
h3. snf-image-helper
56 8 Vangelis Koukis
57 43 Nikos Skalkotos
This part runs inside the helper VM and undertakes customization of the VM being deployed using a number of hooks, or _[[Configuration Tasks|tasks]]_. The tasks run in an environment, specified by rules found in a virtual floppy, placed there by the @snf-image-host@ component. @snf-image-helper@ uses @runparts@ to run tasks found under @/usr/lib/snf-image-helper/tasks@ by default.
58 3 Constantinos Venetsanopoulos
59 14 Vangelis Koukis
The architecture is presented below:
60 11 Constantinos Venetsanopoulos
61 12 Constantinos Venetsanopoulos
h3. Graphical Representation
62 11 Constantinos Venetsanopoulos
63 11 Constantinos Venetsanopoulos
!snf-image_arch.png!
64 11 Constantinos Venetsanopoulos
65 47 Nikos Skalkotos
h3. Image Names
66 47 Nikos Skalkotos
67 47 Nikos Skalkotos
snf-image assumes all image files have the following format:
68 47 Nikos Skalkotos
<pre><image_id>.<image_format></pre>
69 47 Nikos Skalkotos
70 47 Nikos Skalkotos
In order to create an instance with ganeti using an image with filename @debian_base-6.0-5-x86_64.extdump@, you need to specify the following OS parameters:
71 47 Nikos Skalkotos
<pre>img_format=extdump
72 47 Nikos Skalkotos
img_id=debian_base-6.0-5-x86_64</pre>
73 47 Nikos Skalkotos
74 1 Constantinos Venetsanopoulos
h2. Download
75 1 Constantinos Venetsanopoulos
76 79 Nikos Skalkotos
h3. Source
77 1 Constantinos Venetsanopoulos
78 97 Nikos Skalkotos
The latest source packages for snf-image (v0.8) can be found here:
79 97 Nikos Skalkotos
* "@snf-image_0.8.orig.tar.gz@":https://code.grnet.gr/attachments/download/2382/snf-image_0.8.orig.tar.gz
80 97 Nikos Skalkotos
* "@snf-image-helper_0.8.orig.tar.gz@":https://code.grnet.gr/attachments/download/2379/snf-image-helper_0.8.orig.tar.gz
81 79 Nikos Skalkotos
82 79 Nikos Skalkotos
h3. Packages (for debian squeeze)
83 79 Nikos Skalkotos
84 97 Nikos Skalkotos
The latest debian package for snf-image (v0.8) can be found here:
85 97 Nikos Skalkotos
* "@snf-image@":https://code.grnet.gr/attachments/download/2385/snf-image_0.8-1_all.deb
86 10 Vangelis Koukis
87 1 Constantinos Venetsanopoulos
Previous versions and source tarballs can be found here:
88 10 Vangelis Koukis
https://code.grnet.gr/projects/snf-image/files
89 1 Constantinos Venetsanopoulos
90 73 Nikos Skalkotos
You can also download the package from our @apt@ repo:
91 64 Constantinos Venetsanopoulos
92 83 Nikos Skalkotos
http://apt2.dev.grnet.gr
93 64 Constantinos Venetsanopoulos
94 80 Nikos Skalkotos
h3. Fixed snf-image-helper image
95 80 Nikos Skalkotos
96 82 Nikos Skalkotos
If you installed snf-image-host using the provided package, you can create the helper VM by launching `snf-image-update-helper' command. People who installed the program from source may use the fixed helper VM image provided below:
97 80 Nikos Skalkotos
98 94 Nikos Skalkotos
* "@snf_image_helper_image-0.8-1.tar.xz@":https://pithos.okeanos.grnet.gr/public/8e4ph
99 80 Nikos Skalkotos
100 41 Constantinos Venetsanopoulos
h3. Sample Images
101 41 Constantinos Venetsanopoulos
102 41 Constantinos Venetsanopoulos
While developing snf-image, we created and tested a number of images. The following images are basic installations of some popular Linux distributions, that have been tested with snf-image and provided here for testing purposes:
103 41 Constantinos Venetsanopoulos
104 89 Nikos Skalkotos
* Debian Squeeze Base System ["diskdump":https://pithos.okeanos.grnet.gr/public/rjx2r] ["md5sum":https://pithos.okeanos.grnet.gr/public/ngx96] ["metadata":https://pithos.okeanos.grnet.gr/public/b5y5b]
105 89 Nikos Skalkotos
* Debian Desktop ["diskdump":https://pithos.okeanos.grnet.gr/public/cqhm4] ["md5sum":https://pithos.okeanos.grnet.gr/public/964nw] ["metadata":https://pithos.okeanos.grnet.gr/public/ja4e2]
106 90 Nikos Skalkotos
* CentOS 6.0 ["diskdump":https://pithos.okeanos.grnet.gr/public/8rxmc] ["md5sum":https://pithos.okeanos.grnet.gr/public/2am9n] ["metadata":https://pithos.okeanos.grnet.gr/public/gt758]
107 93 Nikos Skalkotos
* Fedora Desktop 17 ["diskdump":https://pithos.okeanos.grnet.gr/public/22y35] ["md5sum":https://pithos.okeanos.grnet.gr/public/g4qft] ["metadata":https://pithos.okeanos.grnet.gr/public/vd4gs]
108 92 Nikos Skalkotos
* Ubuntu Desktop 12.04 ["diskdump":https://pithos.okeanos.grnet.gr/public/max5g] ["md5sum":https://pithos.okeanos.grnet.gr/public/8xyzd] ["metadata":https://pithos.okeanos.grnet.gr/public/cvhnz]
109 91 Nikos Skalkotos
* Kubuntu Desktop 12.04 ["diskdump":https://pithos.okeanos.grnet.gr/public/p54vr] ["md5sum":https://pithos.okeanos.grnet.gr/public/4qyej] ["metadata":https://pithos.okeanos.grnet.gr/public/5nqtp]
110 41 Constantinos Venetsanopoulos
111 41 Constantinos Venetsanopoulos
After getting familiar with snf-image you can build your own Images ([[Image Format|more...]]), or build upon the ones listed above.
112 33 Vangelis Koukis
113 1 Constantinos Venetsanopoulos
h2. Installation
114 1 Constantinos Venetsanopoulos
115 5 Constantinos Venetsanopoulos
Before installing snf-image be sure to have a working Ganeti installation in your cluster. The installation process should take place in *all* ganeti nodes. Here we will describe the installation in a single node. The process is identical for all nodes and should be repeated manually or automatically, e.g., with puppet.
116 5 Constantinos Venetsanopoulos
117 81 Nikos Skalkotos
h3. Installing snf-image using binary packages
118 81 Nikos Skalkotos
119 94 Nikos Skalkotos
# Download the snf-image debian package as described in the download section.
120 94 Nikos Skalkotos
# Install the snf-image debian package:<pre>$ dpkg -i snf-image_0.8-1_all.deb</pre>
121 81 Nikos Skalkotos
# If the dependencies are not met, install all the dependencies using @apt-get -f install@ (or install @snf-image-host@ with @apt-get@).
122 1 Constantinos Venetsanopoulos
# Create the helper VM using the following command:<pre>$ snf-image-update-helper</pre>This command will automatically download all the packages needed to create the helper VM (including snf-image-helper).
123 81 Nikos Skalkotos
124 81 Nikos Skalkotos
h3. Installing snf-image from source
125 81 Nikos Skalkotos
126 94 Nikos Skalkotos
# Download the provided source package:<pre>$ wget https://code.grnet.gr/attachments/download/2382/snf-image_0.8.orig.tar.gz</pre>
127 94 Nikos Skalkotos
# Untar, configure and compile the source:<pre>$ tar -xvf snf-image-host_0.8.orig.tar.gz
128 98 Nikos Skalkotos
$ cd snf-image-0.8
129 81 Nikos Skalkotos
$ ./autoget.sh
130 81 Nikos Skalkotos
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
131 81 Nikos Skalkotos
$ make</pre>
132 81 Nikos Skalkotos
# Install snf-image-host:<pre>$ make install
133 85 Nikos Skalkotos
$ install -Dm600 defaults /etc/default/snf-image</pre>
134 81 Nikos Skalkotos
# Download the fixed snf-image-helper image
135 81 Nikos Skalkotos
# Extract it's content under @/var/lib/snf-image/helper/@:<pre>$ mkdir -p /var/lib/snf-image/helper
136 81 Nikos Skalkotos
$ cd /var/lib/snf-image/helper
137 94 Nikos Skalkotos
$ tar -xvf /place/where/you/stored/snf_image_helper_image-0.8-1.tar.xz</pre>
138 45 Nikos Skalkotos
139 45 Nikos Skalkotos
h2. Configuration
140 1 Constantinos Venetsanopoulos
141 45 Nikos Skalkotos
In this section, we assume that the image file you want to deploy resides under a local directory.
142 73 Nikos Skalkotos
Once you have installed snf-image-host in the Ganeti node, you may need to overwrite the value of the following variables in @/etc/default/snf-image@:
143 55 Constantinos Venetsanopoulos
# *IMAGE_DIR*: This should point to the location where the image files are stored [default: @/var/lib/snf-image@].
144 31 Vangelis Koukis
145 47 Nikos Skalkotos
h2. Sample Usage
146 1 Constantinos Venetsanopoulos
147 65 Constantinos Venetsanopoulos
h3. @diskdump@ images
148 65 Constantinos Venetsanopoulos
149 65 Constantinos Venetsanopoulos
If you want to deploy an image of type @diskdump@, you need to provide the corresponding @img_properties@ as described in the [[Image_Format#OS-parameter-img_properties|Image Format]] section. If using a diskdump found in the Sample Images list, use the @img_properties@ described in the image's metadata file. For example:
150 65 Constantinos Venetsanopoulos
151 65 Constantinos Venetsanopoulos
<pre>gnt-instance add -o snf-image+default --os-parameters img_passwd=SamplePassw0rd,img_format=diskdump,img_id=debian_base-6.0-7-x86_64,img_properties='{"OSFAMILY":"linux"\,"ROOT_PARTITION":"1"}' -t plain --disk=0:size=10G --no-name-check --no-ip-check --no-nics test1</pre>
152 65 Constantinos Venetsanopoulos
153 56 Constantinos Venetsanopoulos
h3. @extdump@/@ntfsdump@ images
154 1 Constantinos Venetsanopoulos
155 56 Constantinos Venetsanopoulos
To create a ganeti instance with snf-image using @debian_base-6.0-5-x86_64.extdump@ hosted under @IMAGE_DIR@, use a command like the one below:
156 56 Constantinos Venetsanopoulos
<pre>gnt-instance add -o snf-image+default --os-parameters img_passwd=SamplePassw0rd,img_format=extdump,img_id=debian_base-6.0-5-x86_64 -t plain --disk=0:size=10G --no-name-check --no-ip-check --no-nics test1</pre>
157 1 Constantinos Venetsanopoulos
158 65 Constantinos Venetsanopoulos
h2. Advanced Usage
159 1 Constantinos Venetsanopoulos
160 65 Constantinos Venetsanopoulos
If you want to learn more and use the advanced features of snf-image please refer to following sections:
161 1 Constantinos Venetsanopoulos
162 76 Nikos Skalkotos
# [[Configuration Tasks|Image Configuration Tasks]]
163 76 Nikos Skalkotos
# [[Image Format|Supported Image formats]]
164 76 Nikos Skalkotos
# [[Image Store|Supported Image store locations]]
165 76 Nikos Skalkotos
# [[PMI|Progress Monitor Interface]]
166 22 Constantinos Venetsanopoulos
167 13 Constantinos Venetsanopoulos
h2. Developers
168 46 Nikos Skalkotos
169 45 Nikos Skalkotos
If you are a developer or want to use the latest source code you can download the latest development version by cloning the snf-image git repository:
170 18 Vangelis Koukis
<pre>$ git clone https://code.grnet.gr/git/snf-image</pre>
171 18 Vangelis Koukis
The _master_ branch contains the latest development version
172 18 Vangelis Koukis
The _debian_ branch contains the _master_ plus the debian packaging directories.
173 24 Constantinos Venetsanopoulos
174 27 Nikos Skalkotos
For more information on how to configure, install or package from source, see the [[Developer|Developer's page]].
175 19 Vangelis Koukis
176 1 Constantinos Venetsanopoulos
h2. Community & Support
177 13 Constantinos Venetsanopoulos
178 13 Constantinos Venetsanopoulos
Your help is very important. Any contributions and bug reports will be highly appreciated. You can contact the team at:
179 1 Constantinos Venetsanopoulos
180 75 Nikos Skalkotos
* Bug reports - feedback - support: synnefo@googlegroups.com