From 4bbe4ecb4fe61275640513a03a4a4fa4746193fe Mon Sep 17 00:00:00 2001
From: Linnnus <linnnus@users.noreply.github.com>
Date: Sat, 15 Feb 2025 10:37:08 +0100
Subject: muhammed/dev-vm: Add development VM

---
 hosts/muhammed/dev-vm/default.nix | 68 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 hosts/muhammed/dev-vm/default.nix

(limited to 'hosts/muhammed/dev-vm/default.nix')

diff --git a/hosts/muhammed/dev-vm/default.nix b/hosts/muhammed/dev-vm/default.nix
new file mode 100644
index 0000000..e7fb05b
--- /dev/null
+++ b/hosts/muhammed/dev-vm/default.nix
@@ -0,0 +1,68 @@
+# This module sets up a development VM which I use for developing Linux stuff
+# on this Darwin host.
+{
+  lib,
+  pkgs,
+  flakeInputs,
+  flakeOutputs,
+  metadata,
+  ...
+}: let
+  workingDirectory = "/var/lib/dev-vm";
+
+  # Port 22 on the guest is forwarded to this port on the host.
+  port = 31023;
+
+  guest-system = import "${pkgs.path}/nixos" {
+    configuration = {
+      imports = [
+        {
+          _module.args = {
+            hostPkgs = pkgs;
+            hostPort = port;
+            inherit workingDirectory flakeInputs flakeOutputs metadata;
+          };
+        }
+        flakeInputs.home-manager.nixosModules.home-manager
+        flakeInputs.agenix.nixosModules.default
+        ./configuration/configuration.nix
+      ];
+    };
+    system = builtins.replaceStrings ["darwin"] ["linux"] pkgs.stdenv.hostPlatform.system;
+  };
+in {
+  system.activationScripts.preActivation.text = ''
+    mkdir -p ${lib.escapeShellArg workingDirectory}
+  '';
+
+  launchd.agents.dev-vm = {
+    script = ''
+      # create-builder uses TMPDIR to share files with the builder, notably certs.
+      # macOS will clean up files in /tmp automatically that haven't been accessed in 3+ days.
+      # If we let it use /tmp, leaving the computer asleep for 3 days makes the certs vanish.
+      # So we'll use /run/org.nixos.dev-vm instead and clean it up ourselves.
+      export TMPDIR=/run/org.nixos.dev-vm
+      export USE_TMPDIR=1
+
+      rm -rf "$TMPDIR"
+      mkdir -p "$TMPDIR"
+      trap 'rm -rf "$TMPDIR"' EXIT
+
+      ${guest-system.config.system.build.macos-vm-installer}/bin/create-builder
+    '';
+
+    serviceConfig = {
+      KeepAlive = true;
+      RunAtLoad = true;
+      WorkingDirectory = workingDirectory;
+    };
+  };
+
+  environment.etc."ssh/ssh_config.d/100-dev-vm.conf".text = ''
+    Host ${guest-system.config.networking.hostName}
+      User linus # Also hardcoded in `configuration.nix`.
+      Hostname localhost
+      Port ${toString port}
+      IdentityFile ${./keys/ssh_vmhost_ed25519_key}
+  '';
+}
-- 
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