1 files changed, 117 insertions, 0 deletions
diff --git a/nixos/lib/testing/network.nix b/nixos/lib/testing/network.nix
new file mode 100644
index 00000000000..04ea9a2bc9f
--- /dev/null
+++ b/nixos/lib/testing/network.nix
@@ -0,0 +1,117 @@
+{ lib, nodes, ... }:
+
+let
+  inherit (lib)
+    attrNames concatMap concatMapStrings flip forEach head
+    listToAttrs mkDefault mkOption nameValuePair optionalString
+    range types zipListsWith zipLists
+    mdDoc
+    ;
+
+  nodeNumbers =
+    listToAttrs
+      (zipListsWith
+        nameValuePair
+        (attrNames nodes)
+        (range 1 254)
+      );
+
+  networkModule = { config, nodes, pkgs, ... }:
+    let
+      interfacesNumbered = zipLists config.virtualisation.vlans (range 1 255);
+      interfaces = forEach interfacesNumbered ({ fst, snd }:
+        nameValuePair "eth${toString snd}" {
+          ipv4.addresses =
+            [{
+              address = "192.168.${toString fst}.${toString config.virtualisation.test.nodeNumber}";
+              prefixLength = 24;
+            }];
+        });
+
+      networkConfig =
+        {
+          networking.hostName = mkDefault config.virtualisation.test.nodeName;
+
+          networking.interfaces = listToAttrs interfaces;
+
+          networking.primaryIPAddress =
+            optionalString (interfaces != [ ]) (head (head interfaces).value.ipv4.addresses).address;
+
+          # Put the IP addresses of all VMs in this machine's
+          # /etc/hosts file.  If a machine has multiple
+          # interfaces, use the IP address corresponding to
+          # the first interface (i.e. the first network in its
+          # virtualisation.vlans option).
+          networking.extraHosts = flip concatMapStrings (attrNames nodes)
+            (m':
+              let config = nodes.${m'}; in
+              optionalString (config.networking.primaryIPAddress != "")
+                ("${config.networking.primaryIPAddress} " +
+                  optionalString (config.networking.domain != null)
+                    "${config.networking.hostName}.${config.networking.domain} " +
+                  "${config.networking.hostName}\n"));
+
+          virtualisation.qemu.options =
+            let qemu-common = import ../qemu-common.nix { inherit lib pkgs; };
+            in
+            flip concatMap interfacesNumbered
+              ({ fst, snd }: qemu-common.qemuNICFlags snd fst config.virtualisation.test.nodeNumber);
+        };
+
+    in
+    {
+      key = "ip-address";
+      config = networkConfig // {
+        # Expose the networkConfig items for tests like nixops
+        # that need to recreate the network config.
+        system.build.networkConfig = networkConfig;
+      };
+    };
+
+  nodeNumberModule = (regular@{ config, name, ... }: {
+    options = {
+      virtualisation.test.nodeName = mkOption {
+        internal = true;
+        default = name;
+        # We need to force this in specilisations, otherwise it'd be
+        # readOnly = true;
+        description = mdDoc ''
+          The `name` in `nodes.<name>`; stable across `specialisations`.
+        '';
+      };
+      virtualisation.test.nodeNumber = mkOption {
+        internal = true;
+        type = types.int;
+        readOnly = true;
+        default = nodeNumbers.${config.virtualisation.test.nodeName};
+        description = mdDoc ''
+          A unique number assigned for each node in `nodes`.
+        '';
+      };
+
+      # specialisations override the `name` module argument,
+      # so we push the real `virtualisation.test.nodeName`.
+      specialisation = mkOption {
+        type = types.attrsOf (types.submodule {
+          options.configuration = mkOption {
+            type = types.submoduleWith {
+              modules = [
+                {
+                  config.virtualisation.test.nodeName =
+                    # assert regular.config.virtualisation.test.nodeName != "configuration";
+                    regular.config.virtualisation.test.nodeName;
+                }
+              ];
+            };
+          };
+        });
+      };
+    };
+  });
+
+in
+{
+  config = {
+    extraBaseModules = { imports = [ networkModule nodeNumberModule ]; };
+  };
+}