Merge pull request #161253 from flokli/kexec-boot

nixos/installer: add kexec-boot

nixos/modules/installer/kexec/kexec-boot.nix

@@ -0,0 +1,51 @@
+# This module exposes a config.system.build.kexecBoot attribute,
+# which returns a directory with kernel, initrd and a shell script
+# running the necessary kexec commands.
+
+# It's meant to be scp'ed to a machine with working ssh and kexec binary
+# installed.
+
+# This is useful for (cloud) providers where you can't boot a custom image, but
+# get some Debian or Ubuntu installation.
+
+{ pkgs
+, modulesPath
+, config
+, ...
+}:
+{
+  imports = [
+    (modulesPath + "/installer/netboot/netboot-minimal.nix")
+  ];
+
+  config = {
+    system.build.kexecBoot =
+      let
+        kexecScript = pkgs.writeScript "kexec-boot" ''
+          #!/usr/bin/env bash
+          if ! kexec -v >/dev/null 2>&1; then
+            echo "kexec not found: please install kexec-tools" 2>&1
+            exit 1
+          fi
+          SCRIPT_DIR=$( cd -- "$( dirname -- "''${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+          kexec --load ''${SCRIPT_DIR}/bzImage \
+            --initrd=''${SCRIPT_DIR}/initrd.gz \
+            --command-line "init=${config.system.build.toplevel}/init ${toString config.boot.kernelParams}"
+          kexec -e
+        ''; in
+      pkgs.linkFarm "kexec-tree" [
+        {
+          name = "initrd.gz";
+          path = "${config.system.build.netbootRamdisk}/initrd";
+        }
+        {
+          name = "bzImage";
+          path = "${config.system.build.kernel}/bzImage";
+        }
+        {
+          name = "kexec-boot";
+          path = kexecScript;
+        }
+      ];
+  };
+}

nixos/tests/kexec.nix

@@ -1,22 +1,46 @@
 # Test whether fast reboots via kexec work.
 
-import ./make-test-python.nix ({ pkgs, lib, ...} : {
+import ./make-test-python.nix ({ pkgs, lib, ... }: {
   name = "kexec";
   meta = with lib.maintainers; {
-    maintainers = [ eelco ];
+    maintainers = [ flokli lassulus ];
   };
 
-  nodes.machine = { ... }:
+  nodes = {
-    { virtualisation.vlans = [ ]; };
+    node1 = { ... }: {
+      virtualisation.vlans = [ ];
+      virtualisation.memorySize = 4 * 1024;
+      virtualisation.useBootLoader = true;
+      virtualisation.useEFIBoot = true;
+      boot.loader.systemd-boot.enable = true;
+      boot.loader.efi.canTouchEfiVariables = true;
+    };
 
-  testScript =
+    node2 = { modulesPath, ... }: {
-    ''
+      virtualisation.vlans = [ ];
-      machine.wait_for_unit("multi-user.target")
+      imports = [
-      machine.succeed('kexec --load /run/current-system/kernel --initrd /run/current-system/initrd --command-line "$(</proc/cmdline)"')
+        "${modulesPath}/installer/kexec/kexec-boot.nix"
-      machine.execute("systemctl kexec >&2 &", check_return=False)
+      ];
-      machine.connected = False
+    };
-      machine.connect()
+  };
-      machine.wait_for_unit("multi-user.target")
+
-      machine.shutdown()
+  testScript = { nodes, ... }: ''
-    '';
+    node1.wait_for_unit("multi-user.target")
+    node1.succeed('kexec --load /run/current-system/kernel --initrd /run/current-system/initrd --command-line "$(</proc/cmdline)"')
+    node1.execute("systemctl kexec >&2 &", check_return=False)
+    node1.connected = False
+    node1.connect()
+    node1.wait_for_unit("multi-user.target")
+
+    # Check the machine with kexec-boot.nix profile boots up
+    node2.wait_for_unit("multi-user.target")
+    node2.shutdown()
+
+    # Kexec node1 to the toplevel of node2 via the kexec-boot script
+    node1.succeed('touch /run/foo')
+    node1.execute('${nodes.node2.config.system.build.kexecBoot}/kexec-boot', check_return=False)
+    node1.succeed('! test -e /run/foo')
+
+    node1.shutdown()
+  '';
 })