feat: capture swap entries

- introduces a `--swap,s` flag which controls whether `/proc/swaps` is captured in the report, `false` by default.
- introduces a `--ephemeral,e` flag which controls whether ephemeral properties are captured in the report, `false` by default and only includes `swap` for now.
- refactors the `basic` vm test to use Disko's testLib and checks more properties of the report output.

Closes #8.

Signed-off-by: Brian McGee <brian@bmcgee.ie>

Author: brianmcgee

cmd/root.go

@@ -19,6 +19,8 @@ var (
 	cfgFile          string
 	outputPath       string
 	hardwareFeatures []string
+
+	scanner = facter.Scanner{}
 )
 
 // rootCmd represents the base command when called without any subcommands
@@ -29,16 +31,15 @@ var rootCmd = &cobra.Command{
 	// todo add Long description
 	RunE: func(cmd *cobra.Command, args []string) error {
 		// convert the hardware features into probe features
-		var hardwareProbes []hwinfo.ProbeFeature
 		for _, str := range hardwareFeatures {
 			probe, err := hwinfo.ProbeFeatureString(str)
 			if err != nil {
 				return fmt.Errorf("invalid hardware feature: %w", err)
 			}
-			hardwareProbes = append(hardwareProbes, probe)
+			scanner.Features = append(scanner.Features, probe)
 		}
 
-		report, err := facter.GenerateReport(hardwareProbes)
+		report, err := scanner.Scan()
 		if err != nil {
 			return err
 		}
@@ -81,7 +82,11 @@ func init() {
 
 	// Cobra also supports local flags, which will only run when this action is called directly.
 	f := rootCmd.Flags()
-	f.StringVarP(&outputPath, "output", "o", "", "Path to write the report")
+	f.StringVarP(&outputPath, "output", "o", "", "path to write the report")
+
+	// Options for optional ephemeral system properties.
+	f.BoolVarP(&scanner.Swap, "swap", "s", false, "capture swap entries")
+	f.BoolVarP(&scanner.Ephemeral, "ephemeral", "e", false, "capture all ephemeral properties e.g. swap, filesystems and so on")
 
 	// We currently support all probe features at a high level as they share some generic information,
 	// but we do not have mappings for all of their detail sections.
@@ -105,11 +110,11 @@ func init() {
 
 	f.StringSliceVarP(
 		&hardwareFeatures,
-		"hardware-features",
+		"hardware",
 		"f",
 		defaultFeatures,
 		fmt.Sprintf(
-			"Hardware features to probe. Possible values are %s",
+			"Hardware items to probe. Possible values are %s",
 			strings.Join(allFeatures, ","),
 		),
 	)

flake.lock

@@ -21,6 +21,7 @@
       url = "github:numtide/treefmt-nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    disko.url = "github:nix-community/disko";
   };
 
   # Keep the magic invocations to minimum.

flake.nix

@@ -7,11 +7,13 @@ require (
 	github.com/klauspost/cpuid/v2 v2.2.9-0.20240805145549-92d5326f011e
 	github.com/spf13/cobra v1.8.1
 	github.com/spf13/viper v1.19.0
+	github.com/stretchr/testify v1.9.0
 )
 
 require (
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
 	github.com/charmbracelet/lipgloss v0.10.0 // indirect
+	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-logfmt/logfmt v0.6.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
@@ -24,6 +26,7 @@ require (
 	github.com/muesli/reflow v0.3.0 // indirect
 	github.com/muesli/termenv v0.15.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect

go.mod

@@ -3,7 +3,9 @@ Copyright © 2024 NAME HERE <EMAIL ADDRESS>
 */
 package main
 
-import "github.com/numtide/nixos-facter/cmd"
+import (
+	"github.com/numtide/nixos-facter/cmd"
+)
 
 func main() {
 	cmd.Execute()

main.go

@@ -1,11 +1,16 @@
-args @ {
+{
   flake,
+  # We need the following pragma to ensure deadnix doesn't remove inputs.
+  # This package is being called with newScope/callPackage, which means it is only being passed args it defines.
+  # We do not use inputs directly in this file, but need it for passing to the tests.
+  # deadnix: skip
+  inputs,
   perSystem,
   system,
   pkgs,
   pname,
   ...
-}: let
+} @ args: let
   inherit (pkgs) go lib;
   fs = lib.fileset;
 in

nix/packages/nixos-facter/default.nix

@@ -10,6 +10,9 @@ schema = 3
   [mod."github.com/charmbracelet/log"]
     version = "v0.4.0"
     hash = "sha256-VQerB44vC646n3fe3haJ3DHa9L5+GRhCfDfm1p3QnZk="
+  [mod."github.com/davecgh/go-spew"]
+    version = "v1.1.2-0.20180830191138-d8f796af33cc"
+    hash = "sha256-fV9oI51xjHdOmEx6+dlq7Ku2Ag+m/bmbzPo6A4Y74qc="
   [mod."github.com/fsnotify/fsnotify"]
     version = "v1.7.0"
     hash = "sha256-MdT2rQyQHspPJcx6n9ozkLbsktIOJutOqDuKpNAtoZY="
@@ -49,6 +52,9 @@ schema = 3
   [mod."github.com/pelletier/go-toml/v2"]
     version = "v2.2.2"
     hash = "sha256-ukxk1Cfm6cQW18g/aa19tLcUu5BnF7VmfAvrDHAOl6A="
+  [mod."github.com/pmezard/go-difflib"]
+    version = "v1.0.1-0.20181226105442-5d4384ee4fb2"
+    hash = "sha256-XA4Oj1gdmdV/F/+8kMI+DBxKPthZ768hbKsO3d9Gx90="
   [mod."github.com/rivo/uniseg"]
     version = "v0.4.7"
     hash = "sha256-rDcdNYH6ZD8KouyyiZCUEy8JrjOQoAkxHBhugrfHjFo="
@@ -76,6 +82,9 @@ schema = 3
   [mod."github.com/spf13/viper"]
     version = "v1.19.0"
     hash = "sha256-MZ8EAvdgpGbw6kmUz8UOaAAAMdPPGd14TrCBAY+A1T4="
+  [mod."github.com/stretchr/testify"]
+    version = "v1.9.0"
+    hash = "sha256-uUp/On+1nK+lARkTVtb5RxlW15zxtw2kaAFuIASA+J0="
   [mod."github.com/subosito/gotenv"]
     version = "v1.6.0"
     hash = "sha256-LspbjTniiq2xAICSXmgqP7carwlNaLqnCTQfw2pa80A="

nix/packages/nixos-facter/gomod2nix.toml

@@ -1,21 +1,76 @@
 {
   pkgs,
-  flake,
+  inputs,
   system,
+  perSystem,
   ...
 }: let
-  inherit (flake.packages.${system}) nixos-facter;
+  # we have to import diskoLib like this because there are some impure default imports e.g. <nixpkgs>
+  diskoLib = import "${inputs.disko}/lib" {
+    inherit (pkgs) lib;
+    makeTest = import "${inputs.nixpkgs}/nixos/tests/make-test-python.nix";
+    eval-config = import "${inputs.nixpkgs}/nixos/lib/eval-config.nix";
+  };
 in
   # for now we only run the tests in x86_64-linux since we don't have access to a bare-metal ARM box or a VM that supports nested
   # virtualization which makes the test take forever and ultimately fail
   pkgs.lib.optionalAttrs pkgs.stdenv.isx86_64 {
-    basic = pkgs.nixosTest {
+    basic = diskoLib.testLib.makeDiskoTest {
+      inherit pkgs;
       name = "basic";
-      nodes.machine = {
-        environment.systemPackages = [nixos-facter];
+      disko-config = ./disko.nix;
+      extraSystemConfig = {
+        environment.systemPackages = [
+          perSystem.self.nixos-facter
+        ];
+
+        systemd.services = {
+          create-swap-files = {
+            serviceConfig.Type = "oneshot";
+            wantedBy = ["multi-user.target"];
+            path = with pkgs; [
+              coreutils
+              util-linux
+            ];
+            script = ''
+              # create some swap files
+              mkdir -p /swap
+              for (( i=1; i<=3; i++ )); do
+                out="/swap/swapfile-$i"
+                dd if=/dev/zero of="$out" bs=1MB count=10
+                chmod 600 "$out"
+                mkswap "$out"
+                swapon "$out"
+              done
+            '';
+          };
+        };
       };
-      testScript = ''
-        machine.succeed("nixos-facter generate report -o /report.json")
+
+      extraTestScript = ''
+        import json
+
+        report = json.loads(machine.succeed("nixos-facter -e"))
+
+        with subtest("Capture system"):
+            assert report['system'] == '${system}'
+
+        with subtest("Capture virtualisation"):
+            virt = report['virtualisation']
+            # kvm for systems that support it, otherwise the vm test should present itself as qemu
+            # todo double-check this is the same for intel
+            assert virt in ("kvm", "qemu"), f"expected virtualisation to be either kvm or qemu, got {virt}"
+
+        with subtest("Capture swap entries"):
+            assert 'swap' in report, "'swap' not found in the report"
+            assert report['swap'] == [
+                { 'path': '/dev/vda4', 'type': 'partition', 'size': 1048572, 'used': 0, 'priority': -2 },
+                { 'path': '/dev/dm-0', 'type': 'partition', 'size': 10236, 'used': 0, 'priority': 100 },
+                { 'path': '/swap/swapfile-1', 'type': 'file', 'size': 9760, 'used': 0, 'priority': -3 },
+                { 'path': '/swap/swapfile-2', 'type': 'file', 'size': 9760, 'used': 0, 'priority': -4 },
+                { 'path': '/swap/swapfile-3', 'type': 'file', 'size': 9760, 'used': 0, 'priority': -5 }
+            ], "swap entries did not match what we expected"
+            # todo is there a nice way of showing a diff?
       '';
     };
   }

nix/packages/nixos-facter/tests/default.nix

@@ -0,0 +1,50 @@
+{
+  disko = {
+    devices = {
+      disk = {
+        main = {
+          device = "/dev/vdb";
+          type = "disk";
+          content = {
+            type = "gpt";
+            partitions = {
+              ESP = {
+                size = "500M";
+                type = "EF00";
+                content = {
+                  type = "filesystem";
+                  format = "vfat";
+                  mountpoint = "/boot";
+                };
+              };
+              root = {
+                end = "-1G";
+                content = {
+                  type = "filesystem";
+                  format = "ext4";
+                  mountpoint = "/";
+                };
+              };
+              encryptedSwap = {
+                size = "10M";
+                content = {
+                  type = "swap";
+                  randomEncryption = true;
+                  priority = 100; # prefer to encrypt as long as we have space for it
+                };
+              };
+              plainSwap = {
+                size = "100%";
+                content = {
+                  type = "swap";
+                  discardPolicy = "both";
+                  resumeDevice = true; # resume from hiberation from this device
+                };
+              };
+            };
+          };
+        };
+      };
+    };
+  };
+}