From bebc30e7fd6fc2da35bb154593a3c6758c8beb29 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Wed, 22 Nov 2023 10:43:59 +0100
Subject: [PATCH] also copy machine-id into installer

This can help with keeping the same dhcp leases when the dhcp server uses DUID rather than mac addresses
---
 nix/installer.nix                | 3 +++
 nix/kexec-installer/kexec-run.sh | 2 ++
 nix/kexec-installer/test.nix     | 6 +++++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/nix/installer.nix b/nix/installer.nix
index 306e38f..33c07ed 100644
--- a/nix/installer.nix
+++ b/nix/installer.nix
@@ -58,5 +58,8 @@
     fi
     install -m 400 ssh/ssh_host_* /mnt-root/etc/ssh
     cp *.json /mnt-root/root/network/
+    if [[ -f machine-id ]]; then
+      cp machine-id /mnt-root/etc/machine-id
+    fi
   '';
 }
diff --git a/nix/kexec-installer/kexec-run.sh b/nix/kexec-installer/kexec-run.sh
index 4e5ade6..71b944b 100644
--- a/nix/kexec-installer/kexec-run.sh
+++ b/nix/kexec-installer/kexec-run.sh
@@ -50,6 +50,8 @@ done
 "$SCRIPT_DIR/ip" -4 --json route > routes-v4.json
 "$SCRIPT_DIR/ip" -6 --json route > routes-v6.json
 
+[ -f /etc/machine-id ] && cp /etc/machine-id machine-id
+
 find . | cpio -o -H newc | gzip -9 >> "$SCRIPT_DIR/initrd"
 
 if ! "$SCRIPT_DIR/kexec" --load "$SCRIPT_DIR/bzImage" \
diff --git a/nix/kexec-installer/test.nix b/nix/kexec-installer/test.nix
index f119bbb..d7b3cf6 100644
--- a/nix/kexec-installer/test.nix
+++ b/nix/kexec-installer/test.nix
@@ -101,7 +101,7 @@ makeTest' {
     node1.succeed("ip -6 route >&2")
     node1.succeed("networkctl status eth0 >&2")
 
-    def ssh(cmd: list[str], check: bool = True, stdout: Optional[int] = None) -> subprocess.CompletedProcess:
+    def ssh(cmd: list[str], check: bool = True, stdout: Optional[int] = None) -> subprocess.CompletedProcess[str]:
         ssh_cmd = [
           "${pkgs.openssh}/bin/ssh",
           "-o", "StrictHostKeyChecking=no",
@@ -128,6 +128,7 @@ makeTest' {
 
     # Kexec node1 to the toplevel of node2 via the kexec-boot script
     node1.succeed('touch /run/foo')
+    old_machine_id = node1.succeed("cat /etc/machine-id").strip()
     node1.fail('parted --version >&2')
     node1.succeed('tar -xf ${kexecTarball}/nixos-kexec-installer-noninteractive-${pkgs.system}.tar.gz -C /root')
     node1.succeed('/root/kexec/ip -V >&2')
@@ -153,6 +154,9 @@ makeTest' {
     print(ssh(["ip", "-6", "route"]))
     print(ssh(["networkctl", "status"]))
 
+    new_machine_id = ssh(["cat", "/etc/machine-id"], stdout=subprocess.PIPE).stdout.strip()
+    assert old_machine_id == new_machine_id, f"{old_machine_id} != {new_machine_id}, machine-id changed"
+
     assert ssh(["ls", "-la", "/run/foo"], check=False).returncode != 0, "kexeced node1 still has /run/foo"
     print(ssh(["parted", "--version"]))
     host = ssh(["hostname"], stdout=subprocess.PIPE).stdout.strip()