From eca08c74169d1dd20c13bfa3500145c09c8507a8 Mon Sep 17 00:00:00 2001
From: Vladimir Timofeenko <id@vtimofeenko.com>
Date: Fri, 23 Dec 2022 18:57:34 -0800
Subject: [PATCH] nix: add development vm

This commit adds back the ability to run a development VM with docspell.
See updated documentation for examples.
---
 nix/checks/configuration-test.nix            |  7 ++-
 nix/dev-vm/default.nix                       | 28 ++++++++++++
 nix/flake.nix                                | 15 +++++++
 website/site/content/docs/dev/development.md | 46 ++++++++------------
 4 files changed, 67 insertions(+), 29 deletions(-)
 create mode 100644 nix/dev-vm/default.nix

diff --git a/nix/checks/configuration-test.nix b/nix/checks/configuration-test.nix
index c78f9b33..bdd3000a 100644
--- a/nix/checks/configuration-test.nix
+++ b/nix/checks/configuration-test.nix
@@ -15,7 +15,7 @@ in
   i18n = {
     defaultLocale = "en_US.UTF-8";
   };
-  console.keyMap = "de";
+  console.keyMap = "us";
 
   users.users.root = {
     password = "root";
@@ -88,6 +88,9 @@ in
     firewall.allowedTCPPorts = [ 7880 ];
   };
 
-  system.stateVersion = "22.05";
+  system.stateVersion = "22.11";
+
+  # This slows down the build of a vm
+  documentation.enable = false;
 
 }
diff --git a/nix/dev-vm/default.nix b/nix/dev-vm/default.nix
new file mode 100644
index 00000000..6f4e93f6
--- /dev/null
+++ b/nix/dev-vm/default.nix
@@ -0,0 +1,28 @@
+# NOTE: modulesPath and imports are taken from nixpkgs#59219
+{ modulesPath, pkgs, lib, ... }: {
+  imports = [ (modulesPath + "/virtualisation/qemu-vm.nix") ];
+  services.openssh = {
+    enable = true;
+    permitRootLogin = "yes";
+  };
+
+  services.docspell-restserver = {
+    openid = lib.mkForce [ ];
+    backend = lib.mkForce {
+      signup = {
+        mode = "open";
+      };
+    };
+  };
+
+  # Otherwise oomkiller kills docspell
+  virtualisation.memorySize = 2048;
+
+  virtualisation.forwardPorts = [
+    # SSH
+    { from = "host"; host.port = 64022; guest.port = 22; }
+    # Docspell
+    { from = "host"; host.port = 64080; guest.port = 7880; }
+  ];
+
+}
diff --git a/nix/flake.nix b/nix/flake.nix
index 633f3cd3..38a87989 100644
--- a/nix/flake.nix
+++ b/nix/flake.nix
@@ -115,5 +115,20 @@
         joex = ((import ./modules/joex.nix) self.overlays.default);
       };
 
+      nixosConfigurations =
+        let
+          lib = nixpkgs.lib;
+        in
+        {
+          dev-vm = lib.makeOverridable nixpkgs.lib.nixosSystem {
+            system = "x86_64-linux";
+            modules = [
+              self.nixosModules.default
+              ./checks
+              # nixos-shell specific module. Should be kept outside nix flake checks
+              ./dev-vm
+            ];
+          };
+        };
     };
 }
diff --git a/website/site/content/docs/dev/development.md b/website/site/content/docs/dev/development.md
index 3720403c..3cc95543 100644
--- a/website/site/content/docs/dev/development.md
+++ b/website/site/content/docs/dev/development.md
@@ -126,43 +126,35 @@ warnings should also be fixed.
 
 # Nix Expressions
 
-The directory `/nix` contains nix expressions to install docspell via
+The directory `/nix` contains Nix Flake to install docspell via
 the nix package manager and to integrate it into NixOS.
 
-## Testing NixOS Modules
+Flake implements `checks` output which can be run with `nix flake check`
+and it defines a development VM which can be used to interactively work
+with docspell.
 
-The modules can be build by building the `configuration-test.nix` file
-together with some nixpkgs version. For example:
+To run the VM, issue:
 
-``` bash
-nixos-rebuild build-vm -I nixos-config=./configuration-test.nix \
-  -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-19.09.tar.gz
+```bash
+cd $PROJECT_ROOT/nix
+nix run '.#nixosConfigurations.dev-vm.config.system.build.vm
 ```
 
-This will build all modules imported in `configuration-test.nix` and
-create a virtual machine containing the system. After that completes,
-the system configuration can be found behind the `./result/system`
-symlink. So it is possible to look at the generated systemd config for
-example:
+To open docspell, wait for docspell-restserver service to report that
+http listener is up and connect to `localhost:64080`.
 
-``` bash
-cat result/system/etc/systemd/system/docspell-joex.service
+To ssh into the machine, run:
+
+```bash
+ssh -o StrictHostKeyChecking=no \
+    -o UserKnownHostsFile=/dev/null \
+    -p 64022 root@localhost
 ```
 
-And with some more commands (there probably is an easier way…) the
-config file can be checked:
+Once connected to the machine, you can see the docspell config file via
 
-``` bash
-cat result/system/etc/systemd/system/docspell-joex.service | grep ExecStart | cut -d'=' -f2 | xargs cat | tail -n1 | awk '{print $NF}'| sed 's/.$//' | xargs cat | jq
-```
-
-To see the module in action, the vm can be started (the first line
-sets more memory for the vm):
-
-``` bash
-export QEMU_OPTS="-m 2048"
-export QEMU_NET_OPTS "hostfwd=tcp::7880-:7880"
-./result/bin/run-docspelltest-vm
+```bash
+systemd-show docspell-joex.service | grep ExecStart | cut -d'=' -f2 | xargs cat | tail -n1 | awk '{print $NF}'| sed 's/.$//' | xargs cat | jq
 ```
 
 # Release