Add possibility to pick root for some domains

README.md

@@ -69,6 +69,7 @@ links:
 domains:
   b:
     enable_v4: false
+    root_path: /path/to/root
 ```
 
 The `links` element is mandatory, each link containing a mandatory `domains`
@@ -86,3 +87,5 @@ domain-specific options.
 The valid options for domains are:
 * `enable_v4`: boolean, specifies whether the domain has IPv4 addresses on its
   NICs.
+* `root_path`: an optional path to a directory containing the root to use for
+  this domain

lxc_net/container.py

@@ -131,7 +131,9 @@ class Container(util.LibvirtObject):
         def __str__(self):
             return "This container is already instanciated"
 
-    def __init__(self, conn, networks, name=None, mem=int(1e6), enable_v4=True):
+    def __init__(
+        self, conn, networks, name=None, mem=int(1e6), enable_v4=True, root_path=None
+    ):
         """Parameters:
         * conn: connection to libvirt,
         * networks: iterable of Network instances this container is connected to,
@@ -139,6 +141,8 @@ class Container(util.LibvirtObject):
         * mem: KiB of memory available to this container,
         * enable_v4: is IPv4 enabled for this container? Defaults to True. If False,
           this container won't be given an IPv4 address.
+        * root_path: if this is not None, the overlayfs for this container will be
+          based on this root directory.
         """
 
         super().__init__(conn)
@@ -151,6 +155,7 @@ class Container(util.LibvirtObject):
         self.mem = mem
         self.enable_v4 = enable_v4
 
+        self.root_path = root_path or settings.BASE_SYSTEM_ROOT
         self.overlay_root = None
 
         self.lxc_container = None
@@ -175,9 +180,11 @@ class Container(util.LibvirtObject):
         for net in self.networks:
             net_config = net_config_templ.inst(
                 mac=util.MACAddress(net.id, self.id),
-                ipv4=util.Addrv4(net.id, self.id)
+                ipv4=(
+                    util.Addrv4(net.id, self.id)
                     if self.enable_v4 and net.enable_v4
-                else None,
+                    else None
+                ),
                 ipv6=util.Addrv6(net.id, self.id),
             )
             net_config_path = net_conf_dir / "11-{link:02d}-{name}.network".format(
@@ -190,10 +197,15 @@ class Container(util.LibvirtObject):
         if self.lxc_container:
             raise self.AlreadyExists()
 
-        self.overlay_root = OverlayDirectory(settings.BASE_SYSTEM_ROOT, name=self.name)
+        self.overlay_root = OverlayDirectory(self.root_path, name=self.name)
 
         self._create_network_files()
 
+        with (self.overlay_root.mount_point / "etc/hostname").open("w") as h:
+            h.write(self.name)
+        with (self.overlay_root.mount_point / "etc/hosts").open("a") as h:
+            h.write(f"127.0.0.1\t{self.name}\n::1\t{self.name}\n")
+
         xml = JinjaTemplate("container.xml").inst(
             name=self.name,
             uuid=self.uuid,

lxc_net/parse_network.py

@@ -239,6 +239,7 @@ class YamlTopology(Topology):
 
             dom_conf = topology["domains"][dom_conf_name]
             dom_descr[dom_conf_name]["enable_v4"] = dom_conf.get("enable_v4", True)
+            dom_descr[dom_conf_name]["root_path"] = dom_conf.get("root_path", None)
 
         sorted_dom_names = sorted(list(dom_descr.keys()))
 
@@ -247,6 +248,7 @@ class YamlTopology(Topology):
                 self.conn,
                 dom_descr[dom]["links"],
                 enable_v4=dom_descr[dom].get("enable_v4", True),
+                root_path=dom_descr[dom].get("root_path", None),
                 name=dom,
             )
             for dom in sorted_dom_names

lxc_net/settings.py

@@ -10,7 +10,7 @@ CONTAINER_BASE_ROOT = "/var/lib/machines/lxc-base-" + PREFIX
 OVERLAYFS_BASE_DIR = "/tmp/{}-overlays/".format(PREFIX)
 
 # Base root
-BASE_SYSTEM_ROOT = "/home/tobast/Machines/lxc-network/_base"
+BASE_SYSTEM_ROOT = "/home/tbastian/Machines/lxc-network/deb12_base"
 
 # The ID of the whole generated network -- below 0xff
 NETWORK_ID = 132