some updates

computelib/utils/__init__.py

@@ -0,0 +1 @@
+from . import mac, xml

computelib/utils/mac.py

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+import random
+
+
+def random_mac() -> str:
+    """Retrun random MAC address."""
+    mac = [0x00, 0x16, 0x3e,
+           random.randint(0x00, 0x7f),
+           random.randint(0x00, 0xff),
+           random.randint(0x00, 0xff)]
+    return ':'.join(map(lambda x: "%02x" % x, mac))

computelib/utils/xml.py

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+from lxml.etree import Element, QName, SubElement
+
+
+class Constructor:
+    """
+    The XML constructor. This class builds XML configs for libvirt.
+    """
+
+    def construct_xml(self,
+                      tag: dict,
+                      namespace: str | None = None,
+                      nsprefix: str | None = None,
+                      root: Element = None) -> Element:
+        """
+        Shortly this recursive function transforms dictonary to XML.
+        Return etree.Element built from dict with following structure::
+
+            {
+                'name': 'device',  # tag name
+                'text': '',  # optional key
+                'values': {  # optional key, must be a dict of key-value pairs
+                    'type': 'disk'
+                },
+                children: []  # optional key, must be a list of dicts
+            }
+
+        Child elements must have the same structure. Infinite `children` nesting
+        is allowed.
+        """
+        use_ns = False
+        if isinstance(namespace, str) and isinstance(nsprefix, str):
+            use_ns = True
+        # Create element
+        if root is None:
+            if use_ns:
+                element = Element(QName(namespace, tag['name']),
+                                  nsmap={nsprefix: namespace})
+            else:
+                element = Element(tag['name'])
+        else:
+            if use_ns:
+                element = SubElement(root, QName(namespace, tag['name']))
+            else:
+                element = SubElement(root, tag['name'])
+        # Fill up element with content
+        if 'text' in tag.keys():
+            element.text = tag['text']
+        if 'values' in tag.keys():
+            for key in tag['values'].keys():
+                element.set(str(key), str(tag['values'][key]))
+        if 'children' in tag.keys():
+            for child in tag['children']:
+                element.append(
+                    self.construct_xml(child,
+                                       namespace=namespace,
+                                       nsprefix=nsprefix,
+                                       root=element))
+        return element
+
+    def add_meta(self, xml: Element, data: dict,
+                 namespace: str, nsprefix: str) -> None:
+        """
+        Add metadata to domain. See:
+        https://libvirt.org/formatdomain.html#general-metadata
+        """
+        metadata = metadata_old = xml.xpath('/domain/metadata')[0]
+        metadata.append(
+            self.construct_xml(
+                data,
+                namespace=namespace,
+                nsprefix=nsprefix,
+            ))
+        xml.replace(metadata_old, metadata)