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libvirtd: Add support for remote libvirt URIs #824

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merged 8 commits into from
Jul 17, 2019
Merged

libvirtd: Add support for remote libvirt URIs #824

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ecd5b44
Upload disk image via libvirt API
erosennin Dec 28, 2017
13f10f8
Add deployment.libvirtd.URI option
erosennin Dec 28, 2017
775323b
Determine QEMU executable via libvirt API
erosennin Dec 28, 2017
0a6100f
libvirtd: remove unused imports
flokli Feb 1, 2018
07a918f
backends.libvirtd: use machine name for temp_image_path
flokli Feb 2, 2018
4914cc6
Update documentation
erosennin Feb 26, 2018
3ac4ca3
Handle libvirt connection errors
erosennin Mar 11, 2018
a7436f0
Connect to libvirtd lazily
erosennin Dec 25, 2018
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104 changes: 95 additions & 9 deletions doc/manual/overview.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -1525,15 +1525,6 @@ add your user to libvirtd group and change firewall not to filter DHCP packets.
</programlisting>
</para>

<para>Next we have to make sure our user has access to create images by
executing:
<programlisting>
$ sudo mkdir /var/lib/libvirt/images
$ sudo chgrp libvirtd /var/lib/libvirt/images
$ sudo chmod g+w /var/lib/libvirt/images
</programlisting>
</para>

<para>We're ready to create the deployment, start by creating
<literal>example.nix</literal>:

Expand Down Expand Up @@ -1602,6 +1593,101 @@ deployment.libvirtd.extraDevicesXML = ''
</para>
</note>

<section>
<title>Remote libvirtd server</title>

<para>
By default, NixOps uses the local libvirtd daemon (<literal>qemu:///system</literal>). It is also possible to
deploy to a
<link xlink:href="https://libvirt.org/remote.html">remote libvirtd server</link>.
Remote deployment requires a couple of things:

<itemizedlist>

<listitem>Pointing <code>deployment.libvirtd.URI</code> to the
<link xlink:href="https://libvirt.org/remote.html">remote libvirtd server</link>
instead of <literal>qemu:///system</literal>.
</listitem>

<listitem>
Configuring the network to ensure the VM running on the remote server is
reachable from the local machine. This is required so that NixOps can reach the
newly created VM by SSH to finish the deployment.
</listitem>

</itemizedlist>
</para>

<para>Example: suppose the remote libvirtd server is located at 10.2.0.15.</para>

<para>
First, create a new <link
xlink:href="https://wiki.libvirt.org/page/TaskRoutedNetworkSetupVirtManager">routed
virtual network</link> on the libvirtd server. In this example we'll use the
192.168.122.0/24 network named <literal>routed</literal>.
</para>

<para>
Next, add a route to the virtual network via the remote libvirtd server. This
can be done by running this command on the local machine:

<screen>
# ip route add to 192.168.122.0/24 via 10.2.0.15
</screen>
</para>

<para>
Now, create a NixOps configuration file <literal>remote-libvirtd.nix</literal>:

<programlisting>{
example = {
deployment.targetEnv = "libvirtd";
deployment.libvirtd.URI = "qemu+ssh://10.2.0.15/system";
deployment.libvirtd.networks = [ "routed" ];
};
}
</programlisting>
</para>

<para>
Finally, deploy it with NixOps:

<screen>
$ nixops create -d remote-libvirtd ./remote-libvirtd.nix
$ nixops deploy -d remote-libvirtd
</screen>
</para>

</section>

<section>
<title>Libvirtd storage pools</title>

<para>
By default, NixOps uses the <literal>default</literal>
<link xlink:href="https://libvirt.org/storage.html">storage pool</link> which
usually corresponds to the <filename>/var/lib/libvirt/images</filename>
directory. You can choose another storage pool with the
<code>deployment.libvirtd.storagePool</code> option:

<programlisting>
{
example = {
deployment.targetEnv = "libvirtd";
deployment.libvirtd.storagePool = "mystoragepool";
};
}
</programlisting>
</para>

<warning>
<para>NixOps has only been tested with storage pools of type <code>dir</code> (filesystem directory).
Attempting to use a storage pool of any other type with NixOps may not work as expected.
</para>
</warning>

</section>

</section>

<section><title>Deploying Datadog resources</title>
Expand Down
16 changes: 12 additions & 4 deletions nix/libvirtd.nix
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Expand Up @@ -45,11 +45,19 @@ in
###### interface

options = {
deployment.libvirtd.imageDir = mkOption {
type = types.path;
default = "/var/lib/libvirt/images";
deployment.libvirtd.storagePool = mkOption {
type = types.str;
default = "default";
description = ''
The storage pool where the virtual disk is be created.
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"is be"

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is it possible to add an example ?

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Thanks, fixed. :)

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Not sure about the example here. This option is just the name of the libvirt storage pool. By default, there is a single storage pool named "default" which points to the /var/lib/libvirt/images directory. It is really hard for me to come up with a meaningful example here other than "default" here. :) But we already use "default" as the default value.

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I see. I was not familiar with the terminology so this is the name of the storage pool ty

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Edited the description, should be more clear this way.

'';
};

deployment.libvirtd.URI = mkOption {
type = types.str;
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Could this benefit from types.enum?

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This may or may not reveal how little I know about libvirt :-)

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Could this benefit from types.enum?

Probably not, this option can be an arbitrary URI string: https://libvirt.org/uri.html.

It would be nice to have types.URL and types.URI though. :)

default = "qemu:///system";
description = ''
Directory to store VM image files. Note that it should be writable both by you and by libvirtd daemon.
Connection URI.
'';
};

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