openstack/openstack-manuals
Code Issues Proposed changes
4c3b903538
openstack-manuals/doc/common/section_user-data.xml
Diane Fleming 64b6c9261e Folder rename, file rename, flattening of directories 
Current folder name	New folder name	        Book title
----------------------------------------------------------
basic-install 	        DELETE
cli-guide	        DELETE
common	                common
NEW	                admin-guide-cloud	Cloud Administrators Guide
docbkx-example	        DELETE
openstack-block-storage-admin 	DELETE
openstack-compute-admin 	DELETE
openstack-config 	config-reference	OpenStack Configuration Reference
openstack-ha 	        high-availability-guide	OpenStack High Availabilty Guide
openstack-image	        image-guide	OpenStack Virtual Machine Image Guide
openstack-install 	install-guide	OpenStack Installation Guide
openstack-network-connectivity-admin 	admin-guide-network 	OpenStack Networking Administration Guide
openstack-object-storage-admin 	DELETE
openstack-security 	security-guide	OpenStack Security Guide
openstack-training 	training-guide	OpenStack Training Guide
openstack-user 	        user-guide	OpenStack End User Guide
openstack-user-admin 	user-guide-admin	OpenStack Admin User Guide
glossary	        NEW        	OpenStack Glossary

bug: #1220407

Change-Id: Id5ffc774b966ba7b9a591743a877aa10ab3094c7
author: diane fleming
2013-09-08 15:15:50 -07:00

206 lines
12 KiB
XML
Raw Blame History

<?xml version="1.0" encoding="UTF-8"?>
<section
xmlns="http://docbook.org/ns/docbook"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xlink="http://www.w3.org/1999/xlink"
version="5.0"
xml:id="user-data">
<title>Configuring instances at boot time</title>
<simplesect>
<title>Introduction</title>
<para>Users often want to do some configuration to their instances after booting. For
example, you may want to install some packages, start services, or manage the instance
using a Puppet or Chef server. When launching instances in an OpenStack cloud, there are
two technologies that work together to support automated configuration of instances at
boot time: user data and cloud-init.</para>
</simplesect>
<simplesect>
<title>User data</title>
<para>User data is the mechanism by which a user can pass information contained in a local
file to an instance at launch time. The typical use case is to pass something like a
shell script or a configuration file as user data.</para>
<para>User data is sent using the <literal>--user-data
<replaceable>/path/to/filename</replaceable></literal> option when calling
<command>nova boot</command>. The following example creates a text file and then
send the contents of that file as user data to the instance.</para>
<para>
<screen><prompt>$</prompt> <userinput>echo "This is some text" > myfile.txt</userinput>
<prompt>$</prompt> <userinput>nova boot --user-data ./myfile.txt --image myimage myinstance</userinput></screen>
</para>
<para>The instance can retrieve user data by querying the metadata service at using either
the OpenStack metadata API or the EC2 compatibility API:</para>
<para>
<screen><prompt>$</prompt> <userinput>curl http://169.254.169.254/2009-04-04/user-data</userinput>
<computeroutput>This is some text</computeroutput>
<prompt>$</prompt> <userinput>curl http://169.254.169.254/openstack/2012-08-10/user_data</userinput>
<computeroutput>This is some text</computeroutput></screen>
</para>
<para>Note that the Compute service treats user data as a blob. While the example above used
a text file, user data can be in any format.</para>
</simplesect>
<simplesect>
<title>Cloud-init</title>
<para>To do something useful with the user data, the virtual machine image must be
configured to run a service on boot that retrieves the user data from the metadata
service and take some action based on the contents of the data. The cloud-init package
was designed to do exactly this. In particular, cloud-init is compatible with the
Compute metadata service as well as the Compute config drive.</para>
<para>Note that cloud-init is not an OpenStack technology. Rather, it is a package that is
designed to support multiple cloud providers, so that the same virtual machine image can
be used in different clouds without modification. Cloud-init is an open source project,
and the source code is available on <link xlink:href="http://launchpad.net/cloud-init"
>Launchpad</link>. It is maintained by Canonical, the company which runs the Ubuntu
project. All Ubuntu cloud images come pre-installed with cloud-init. However, cloud-init
is not designed to be Ubuntu-specific, and has been successfully ported to
Fedora.</para>
<para>We recommend installing cloud-init on images that you create to simplify the task of
configuring your instances on boot. Even if you do not wish to use user data to
configure instance behavior at boot time, cloud-init provides useful functionality such
as copying the public key to an account (the <literal>ubuntu</literal> account by
default on Ubuntu instances, the <literal>ec2-user</literal> by default in Fedora
instances).</para>
<para>If you do not have cloud-init installed, you will need to manually configure your
image to retrieve the public key from the metadata service on boot and copy it to the
appropriate account.</para>
</simplesect>
<simplesect>
<title>Cloud-init supported formats and documentation</title>
<para>We recommend taking a look at the cloud-init <link
xlink:href="http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/doc/userdata.txt"
>doc/userdata.txt</link> file the <link
xlink:href="http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/files/head:/doc/examples/"
>examples</link> directory as well as the <link
xlink:href="https://help.ubuntu.com/community/CloudInit">Ubuntu community
documentation</link> for details on how to use cloud-init. We provide some basic
examples here.</para>
<para>Cloud-init supports several different input formats for user data. We briefly discuss
two commonly used formats:<itemizedlist>
<listitem>
<para>Shell scripts (starts with <literal>#!</literal>)</para>
</listitem>
<listitem>
<para>Cloud config files (starts with <literal>#cloud-config</literal>)</para>
</listitem>
</itemizedlist></para>
</simplesect>
<simplesect>
<title>Running a shell script on boot</title>
<para>Assuming you have cloud-init installed, the simplest way to configure an instance on
boot is to pass a shell script as user data. The shell file must begin with
<literal>#!</literal> in order for cloud-init to recognize it as a shell script.
Here's an example of a script that creates an account called
<literal>clouduser</literal>.</para>
<para><programlisting language="bash">#!/bin/bash
adduser --disabled-password --gecos "" clouduser</programlisting>Sending
a shell script as user data has a similar effect to writing an
<filename>/etc/rc.local</filename> script: it will be executed very late in the boot
sequence as root.</para>
</simplesect>
<simplesect><title>Cloud-config format</title>
<para>Cloud-init supports a YAML-based config format that allows the user to configure a
large number of options on a system. User data that begins with
<literal>#cloud-config</literal> will be interpreted by cloud-init as cloud-config
format.</para>
</simplesect>
<simplesect>
<title>Example: Setting hostname</title>
<para>This cloud-init user data example sets the hostname and the FQDN, as well as updating
<filename>/etc/hosts</filename> on the instance:</para>
<para>
<programlisting>#cloud-config
hostname: mynode
fqdn: mynode.example.com
manage_etc_hosts: true</programlisting>
</para>
</simplesect>
<simplesect>
<title>Example: Configuring instances with Puppet</title>
<para>This cloud-init user data example, based on <link
xlink:href="http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/doc/examples/cloud-config-puppet.txt"
>doc/examples/cloud-config-puppet.txt</link>, would configure the instance to
contact a Puppet server at puppetmaster.example.org and verify its identity using a
certificate.
<programlisting>#cloud-config
puppet:
conf:
agent:
server: "puppetmaster.example.org"
ca_cert: |
-----BEGIN CERTIFICATE-----
MIICCTCCAXKgAwIBAgIBATANBgkqhkiG9w0BAQUFADANMQswCQYDVQQDDAJjYTAe
Fw0xMDAyMTUxNzI5MjFaFw0xNTAyMTQxNzI5MjFaMA0xCzAJBgNVBAMMAmNhMIGf
MA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCu7Q40sm47/E1Pf+r8AYb/V/FWGPgc
b014OmNoX7dgCxTDvps/h8Vw555PdAFsW5+QhsGr31IJNI3kSYprFQcYf7A8tNWu
1MASW2CfaEiOEi9F1R3R4Qlz4ix+iNoHiUDTjazw/tZwEdxaQXQVLwgTGRwVa+aA
qbutJKi93MILLwIDAQABo3kwdzA4BglghkgBhvhCAQ0EKxYpUHVwcGV0IFJ1Ynkv
T3BlblNTTCBHZW5lcmF0ZWQgQ2VydGlmaWNhdGUwDwYDVR0TAQH/BAUwAwEB/zAd
BgNVHQ4EFgQUu4+jHB+GYE5Vxo+ol1OAhevspjAwCwYDVR0PBAQDAgEGMA0GCSqG
SIb3DQEBBQUAA4GBAH/rxlUIjwNb3n7TXJcDJ6MMHUlwjr03BDJXKb34Ulndkpaf
+GAlzPXWa7bO908M9I8RnPfvtKnteLbvgTK+h+zX1XCty+S2EQWk29i2AdoqOTxb
hppiGMp0tT5Havu4aceCXiy2crVcudj3NFciy8X66SoECemW9UYDCb9T5D0d
-----END CERTIFICATE-----</programlisting></para>
</simplesect>
<simplesect>
<title>Example: Configuring instances with Chef</title>
<para>This cloud-init user data example, based on <link
xlink:href="http://bazaar.launchpad.net/~cloud-init-dev/cloud-init/trunk/view/head:/doc/examples/cloud-config-chef.txt"
>doc/examples/cloud-config/chef.txt</link>, and intended for use in an Ubuntu image,
would add the Chef apt repository, install Chef, connect to a Chef server at
https://chefserver.example.com:4000 and install
Apache.<programlisting>#cloud-config
apt_sources:
- source: "deb http://apt.opscode.com/ $RELEASE-0.10 main"
key: |
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.4.9 (GNU/Linux)
mQGiBEppC7QRBADfsOkZU6KZK+YmKw4wev5mjKJEkVGlus+NxW8wItX5sGa6kdUu
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DAAKCRApQKupg++CauISAJ9CxYPOKhOxalBnVTLeNUkAHGg2gACeIsbobtaD4ZHG
0GLl8EkfA8uhluM=
=zKAm
-----END PGP PUBLIC KEY BLOCK-----
chef:
install_type: "packages"
server_url: "https://chefserver.example.com:4000"
node_name: "your-node-name"
environment: "production"
validation_name: "yourorg-validator"
validation_key: |
-----BEGIN RSA PRIVATE KEY-----
YOUR-ORGS-VALIDATION-KEY-HERE
-----END RSA PRIVATE KEY-----
run_list:
- "recipe[apache2]"
- "role[db]"
initial_attributes:
apache:
prefork:
maxclients: 100
keepalive: "off"</programlisting></para>
</simplesect>
</section>
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