properly use modular function application to ensure parameter type-checks

Closes #103

At last, a fully fledged data model for what Fediversity really is and does. This comes with a test that exercises a very simple but functionally complete arrangement with all ingredients fo the business logic: a dummy resource (login shell), a dummy application (`hello`, which needs a shell to live in), a dummy environment (a single NixOS VM that allows for one, the operator's, login shell), and a deployment of that environment given a dummy configuration (that enables `hello`).

The next step will be to lift this purely evaluation-level test into a VM test which verifies that the resulting VM indeed has `hello` deployed to the operator's user account.

Caveats:
- The exact naming has a bit of room for improvement, and may have diverged from the design document
- The test is not as pedantically type safe as it could be, since we simply use `types.raw` for resources such as NixOS users settings which *could* be more finely delineated

Co-authored-by: Kiara Grouwstra <kiara@procolix.eu>
Co-authored-by: kiara Grouwstra <kiara@procolix.eu>
Reviewed-on: Fediversity/Fediversity#481
Reviewed-by: kiara Grouwstra <kiara@procolix.eu>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-committed-by: Valentin Gagarin <valentin.gagarin@tweag.io>

.forgejo/workflows/ci.yaml

@@ -56,3 +56,29 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - run: nix build .#checks.x86_64-linux.deployment-panel -L
+
+  ## NOTE: NixOps4 does not provide a good “dry run” mode, so we instead check
+  ## proxies for resources, namely whether their `.#vmOptions.<machine>` and
+  ## `.#nixosConfigurations.<machine>` outputs evaluate and build correctly, and
+  ## whether we can dry run `infra/proxmox-*.sh` on them. This will not catch
+  ## everything, and in particular not issues in how NixOps4 wires up the
+  ## resources, but that is still something.
+  check-resources:
+    runs-on: native
+    steps:
+      - uses: actions/checkout@v4
+      - run: |
+          set -euC
+          echo ==================== [ VM Options ] ====================
+          machines=$(nix eval --impure --raw --expr 'with builtins; toString (attrNames (getFlake (toString ./.)).vmOptions)')
+          for machine in $machines; do
+            echo ~~~~~~~~~~~~~~~~~~~~~: $machine :~~~~~~~~~~~~~~~~~~~~~
+            nix build .#checks.x86_64-linux.vmOptions-$machine
+          done
+          echo
+          echo ==================== [ NixOS Configurations ] ====================
+          machines=$(nix eval --impure --raw --expr 'with builtins; toString (attrNames (getFlake (toString ./.)).nixosConfigurations)')
+          for machine in $machines; do
+            echo ~~~~~~~~~~~~~~~~~~~~~: $machine :~~~~~~~~~~~~~~~~~~~~~
+            nix build .#checks.x86_64-linux.nixosConfigurations-$machine
+          done

deployment/check/common/nixosTest.nix

@@ -48,7 +48,8 @@ in
     extraTestScript = mkOption { };
 
     sourceFileset = mkOption {
-      ## REVIEW: Upstream to nixpkgs?
+      ## FIXME: grab `lib.types.fileset` from NixOS, once upstreaming PR
+      ## https://github.com/NixOS/nixpkgs/pull/428293 lands.
       type = types.mkOptionType {
         name = "fileset";
         description = "fileset";

infra/common/options.nix

@@ -20,16 +20,13 @@ in
       '';
     };
 
-    proxmox = mkOption {
-      type = types.nullOr (
-        types.enum [
-          "procolix"
-          "fediversity"
-        ]
-      );
+    isFediversityVm = mkOption {
+      type = types.bool;
       description = ''
-        The Proxmox instance. This is used for provisioning only and should be
-        set to `null` if the machine is not a VM.
+        Whether the machine is a Fediversity VM or not. This is used to
+        determine whether the machine should be provisioned via Proxmox or not.
+        Machines that are _not_ Fediversity VM could be physical machines, or
+        VMs that live outside Fediversity, eg. on Procolix's Proxmox.
       '';
     };
 

infra/common/proxmox-qemu-vm.nix

@@ -1,10 +1,14 @@
-{ sources, ... }:
+{ ... }:
+
 {
   _class = "nixos";
 
-  imports = [
-    "${sources.nixpkgs}/nixos/modules/profiles/qemu-guest.nix"
-  ];
+  ## FIXME: It would be nice, but the following leads to infinite recursion
+  ## in the way we currently plug `sources` in.
+  ##
+  # imports = [
+  #   "${sources.nixpkgs}/nixos/modules/profiles/qemu-guest.nix"
+  # ];
 
   boot = {
     initrd = {

infra/common/resource.nix

@@ -2,7 +2,6 @@
   inputs,
   lib,
   config,
-  sources,
   keys,
   secrets,
   ...
@@ -33,10 +32,9 @@ in
   ## should go into the `./nixos` subdirectory.
   nixos.module = {
     imports = [
-      "${sources.agenix}/modules/age.nix"
-      "${sources.disko}/module.nix"
       ./options.nix
       ./nixos
+      ./proxmox-qemu-vm.nix
     ];
 
     ## Inject the shared options from the resource's `config` into the NixOS

infra/flake-part.nix

@@ -14,49 +14,38 @@ let
     mkOption
     evalModules
     filterAttrs
+    mapAttrs'
+    deepSeq
     ;
   inherit (lib.attrsets) genAttrs;
 
-  ## Given a machine's name and whether it is a test VM, make a resource module,
-  ## except for its missing provider. (Depending on the use of that resource, we
-  ## will provide a different one.)
-  makeResourceModule =
-    { vmName, isTestVm }:
-    {
-      nixos.module.imports = [
-        ./common/proxmox-qemu-vm.nix
-      ];
-
-      nixos.specialArgs = {
+  commonResourceModule = {
+    # TODO(@fricklerhandwerk): this is terrible but IMO we should just ditch
+    # flake-parts and have our own data model for how the project is organised
+    # internally
+    _module.args = {
       inherit
-          sources
         inputs
         keys
         secrets
+        sources
         ;
     };
 
-      imports =
-        [
-          ./common/resource.nix
-        ]
-        ++ (
-          if isTestVm then
-            [
-              ../machines/operator/${vmName}
-              {
-                nixos.module.users.users.root.openssh.authorizedKeys.keys = [
-                  # allow our panel vm access to the test machines
-                  keys.panel
+    ## FIXME: It would be preferrable to have those `sources`-related imports in
+    ## the modules that use them. However, doing so triggers infinite recursions
+    ## because of the way we propagate `sources`. `sources` must be propagated by
+    ## means of `specialArgs`, but this requires a bigger change.
+    nixos.module.imports = [
+      "${sources.nixpkgs}/nixos/modules/profiles/qemu-guest.nix"
+      "${sources.agenix}/modules/age.nix"
+      "${sources.disko}/module.nix"
+      "${sources.home-manager}/nixos"
+    ];
+
+    imports = [
+      ./common/resource.nix
     ];
-              }
-            ]
-          else
-            [
-              ../machines/dev/${vmName}
-            ]
-        );
-      fediversityVm.name = vmName;
   };
 
   ## Given a list of machine names, make a deployment with those machines'
@@ -65,40 +54,16 @@ let
     vmNames:
     { providers, ... }:
     {
-      # XXX: this type merge is for adding `specialArgs` to resource modules
-      options.resources = mkOption {
-        type =
-          with lib.types;
-          lazyAttrsOf (submoduleWith {
-            class = "nixops4Resource";
-            modules = [ ];
-            # TODO(@fricklerhandwerk): we may want to pass through all of `specialArgs`
-            # once we're sure it's sane. leaving it here for better control during refactoring.
-            specialArgs = {
-              inherit
-                sources
-                inputs
-                keys
-                secrets
-
-                ;
-            };
-          });
-      };
-      config = {
       providers.local = inputs.nixops4.modules.nixops4Provider.local;
       resources = genAttrs vmNames (vmName: {
         type = providers.local.exec;
         imports = [
           inputs.nixops4-nixos.modules.nixops4Resource.nixos
-            (makeResourceModule {
-              inherit vmName;
-              isTestVm = false;
-            })
+          commonResourceModule
+          ../machines/dev/${vmName}
         ];
       });
     };
-    };
   makeDeployment' = vmName: makeDeployment [ vmName ];
 
   ## Given an attrset of test configurations (key = test machine name, value =
@@ -112,21 +77,29 @@ let
         fediversity = import ../services/fediversity;
       }
       {
-        garageConfigurationResource = makeResourceModule {
-          vmName = "test01";
-          isTestVm = true;
+        garageConfigurationResource = {
+          imports = [
+            commonResourceModule
+            ../machines/operator/test01
+          ];
         };
-        mastodonConfigurationResource = makeResourceModule {
-          vmName = "test06"; # somehow `test02` has a problem - use test06 instead
-          isTestVm = true;
+        mastodonConfigurationResource = {
+          imports = [
+            commonResourceModule
+            ../machines/operator/test06 # somehow `test02` has a problem - use test06 instead
+          ];
         };
-        peertubeConfigurationResource = makeResourceModule {
-          vmName = "test05";
-          isTestVm = true;
+        peertubeConfigurationResource = {
+          imports = [
+            commonResourceModule
+            ../machines/operator/test05
+          ];
         };
-        pixelfedConfigurationResource = makeResourceModule {
-          vmName = "test04";
-          isTestVm = true;
+        pixelfedConfigurationResource = {
+          imports = [
+            commonResourceModule
+            ../machines/operator/test04
+          ];
         };
       };
 
@@ -139,54 +112,63 @@ let
     ## this is only needed to expose NixOS configurations for provisioning
     ## purposes, and eventually all of this should be handled by NixOps4.
     options = {
-      nixos.module = mkOption { }; # NOTE: not just `nixos` otherwise merging will go wrong
+      nixos.module = mkOption { type = lib.types.deferredModule; }; # NOTE: not just `nixos` otherwise merging will go wrong
       nixpkgs = mkOption { };
       ssh = mkOption { };
     };
   };
 
   makeResourceConfig =
-    vm:
+    { vmName, isTestVm }:
     (evalModules {
       modules = [
         nixops4ResourceNixosMockOptions
-        (makeResourceModule vm)
+        commonResourceModule
+        (if isTestVm then ../machines/operator/${vmName} else ../machines/dev/${vmName})
       ];
     }).config;
 
   ## Given a VM name, make a NixOS configuration for this machine.
   makeConfiguration =
     isTestVm: vmName:
-    let
-      inherit (sources) nixpkgs;
-    in
-    import "${nixpkgs}/nixos" {
-      modules = [
-        (makeResourceConfig { inherit vmName isTestVm; }).nixos.module
-      ];
+    import "${sources.nixpkgs}/nixos" {
+      configuration = (makeResourceConfig { inherit vmName isTestVm; }).nixos.module;
+      system = "x86_64-linux";
     };
 
-  makeVmOptions = isTestVm: vmName: {
-    inherit ((makeResourceConfig { inherit vmName isTestVm; }).fediversityVm)
-      proxmox
+  makeVmOptions =
+    isTestVm: vmName:
+    let
+      config = (makeResourceConfig { inherit vmName isTestVm; }).fediversityVm;
+    in
+    if config.isFediversityVm then
+      {
+        inherit (config)
           vmId
           description
-
           sockets
           cores
           memory
           diskSize
-
           hostPublicKey
           unsafeHostPrivateKey
           ;
-  };
+      }
+    else
+      null;
 
   listSubdirectories = path: attrNames (filterAttrs (_: type: type == "directory") (readDir path));
 
   machines = listSubdirectories ../machines/dev;
   testMachines = listSubdirectories ../machines/operator;
 
+  nixosConfigurations =
+    genAttrs machines (makeConfiguration false)
+    // genAttrs testMachines (makeConfiguration true);
+  vmOptions =
+    filterAttrs (_: value: value != null) # Filter out non-Fediversity VMs
+      (genAttrs machines (makeVmOptions false) // genAttrs testMachines (makeVmOptions true));
+
 in
 {
   _class = "flake";
@@ -210,10 +192,23 @@ in
       )
     );
   };
-  flake.nixosConfigurations =
-    genAttrs machines (makeConfiguration false)
-    // genAttrs testMachines (makeConfiguration true);
-  flake.vmOptions =
-    genAttrs machines (makeVmOptions false)
-    // genAttrs testMachines (makeVmOptions true);
+  flake = { inherit nixosConfigurations vmOptions; };
+
+  perSystem =
+    { pkgs, ... }:
+    {
+      checks =
+        mapAttrs' (name: nixosConfiguration: {
+          name = "nixosConfigurations-${name}";
+          value = nixosConfiguration.config.system.build.toplevel;
+        }) nixosConfigurations
+        // mapAttrs' (name: vmOptions: {
+          name = "vmOptions-${name}";
+          ## Check that VM options builds/evaluates correctly. `deepSeq e1
+          ## e2` evaluates `e1` strictly in depth before returning `e2`. We
+          ## use this trick because checks need to be derivations, which VM
+          ## options are not.
+          value = deepSeq vmOptions pkgs.hello;
+        }) vmOptions;
+    };
 }

infra/proxmox-provision.sh

@@ -179,15 +179,9 @@ grab_vm_options () {
     --log-format raw --quiet
   )
 
-  proxmox=$(echo "$options" | jq -r .proxmox)
   vm_id=$(echo "$options" | jq -r .vmId)
   description=$(echo "$options" | jq -r .description)
 
-  if [ "$proxmox" != fediversity ]; then
-    die "I do not know how to provision things that are not Fediversity VMs,
-but I got proxmox = '%s' for VM %s." "$proxmox" "$vm_name"
-  fi
-
   sockets=$(echo "$options" | jq -r .sockets)
   cores=$(echo "$options" | jq -r .cores)
   memory=$(echo "$options" | jq -r .memory)

infra/proxmox-remove.sh

@@ -167,16 +167,10 @@ grab_vm_options () {
       --log-format raw --quiet
     )
 
-    proxmox=$(echo "$options" | jq -r .proxmox)
     vm_id=$(echo "$options" | jq -r .vmId)
 
-    if [ "$proxmox" != fediversity ]; then
-      die "I do not know how to remove things that are not Fediversity VMs,
-  but I got proxmox = '%s' for VM %s." "$proxmox" "$vm_name"
-    fi
-
-    printf 'done grabing VM options for VM %s. Found VM %d on %s Proxmox.\n' \
-      "$vm_name" "$vm_id" "$proxmox"
+    printf 'done grabing VM options for VM %s. Got id: %d.\n' \
+      "$vm_name" "$vm_id"
   fi
 }
 

machines/dev/fedi200/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "fedi200";
+    isFediversityVm = true;
     vmId = 200;
-    proxmox = "fediversity";
     description = "Testing machine for Hans";
 
     domain = "abundos.eu";
@@ -16,10 +17,4 @@
       gateway = "2a00:51c0:13:1305::1";
     };
   };
-
-  nixos.module = {
-    imports = [
-      ../../../infra/common/proxmox-qemu-vm.nix
-    ];
-  };
 }

machines/dev/fedi201/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "fedi201";
+    isFediversityVm = true;
     vmId = 201;
-    proxmox = "fediversity";
     description = "FediPanel";
 
     domain = "abundos.eu";
@@ -19,7 +20,6 @@
 
   nixos.module = {
     imports = [
-      ../../../infra/common/proxmox-qemu-vm.nix
       ./fedipanel.nix
     ];
   };

machines/dev/fedi201/fedipanel.nix

@@ -1,6 +1,5 @@
 {
   config,
-  sources,
   ...
 }:
 let
@@ -11,7 +10,6 @@ in
 
   imports = [
     (import ../../../panel { }).module
-    "${sources.home-manager}/nixos"
   ];
 
   security.acme = {

machines/dev/forgejo-ci/default.nix

@@ -20,7 +20,9 @@ in
   ssh.host = mkForce "forgejo-ci";
 
   fediversityVm = {
+    name = "forgejo-ci";
     domain = "procolix.com";
+    isFediversityVm = false;
 
     ipv4 = {
       interface = "enp1s0f0";

machines/dev/vm02116/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "vm02116";
+    isFediversityVm = false;
     vmId = 2116;
-    proxmox = "procolix";
     description = "Forgejo";
 
     ipv4.address = "185.206.232.34";
@@ -14,7 +15,6 @@
     { lib, ... }:
     {
       imports = [
-        ../../../infra/common/proxmox-qemu-vm.nix
         ./forgejo.nix
       ];
 

machines/dev/vm02187/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "vm02187";
+    isFediversityVm = false;
     vmId = 2187;
-    proxmox = "procolix";
     description = "Wiki";
 
     ipv4.address = "185.206.232.187";
@@ -14,7 +15,6 @@
     { lib, ... }:
     {
       imports = [
-        ../../../infra/common/proxmox-qemu-vm.nix
         ./wiki.nix
       ];
 

machines/operator/test01/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test01";
+    isFediversityVm = true;
     vmId = 7001;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test02/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test02";
+    isFediversityVm = true;
     vmId = 7002;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test03/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test03";
+    isFediversityVm = true;
     vmId = 7003;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test04/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test04";
+    isFediversityVm = true;
     vmId = 7004;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test05/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test05";
+    isFediversityVm = true;
     vmId = 7005;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test06/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test06";
+    isFediversityVm = true;
     vmId = 7006;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test11/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test11";
+    isFediversityVm = true;
     vmId = 7011;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test12/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test12";
+    isFediversityVm = true;
     vmId = 7012;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test13/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test13";
+    isFediversityVm = true;
     vmId = 7013;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;

machines/operator/test14/default.nix

@@ -2,8 +2,9 @@
   _class = "nixops4Resource";
 
   fediversityVm = {
+    name = "test14";
+    isFediversityVm = true;
     vmId = 7014;
-    proxmox = "fediversity";
 
     hostPublicKey = builtins.readFile ./ssh_host_ed25519_key.pub;
     unsafeHostPrivateKey = builtins.readFile ./ssh_host_ed25519_key;