subflakes: make first class citizens

Subflakes should provide their wares as outputs, so wire up the pkgs
flake to reflect that.

Due to the unstable nature of flakes, updating the root flake doesn't
currently update the subflake lock file. Therefore, add additional
logic to flk update script in order to do this behind the scenes.

Nix is now pulled in from the "nix" registry flake in order for users
to take advantage of improvements to the UI since its last update in
nixpkgs.

doc/flk/update.md

@@ -1,16 +1,22 @@
 # update
 The `update` subcommand is a simple alias for:
 ```sh
-nix flake update --recreate-lock-file --commit-lock-file
+nix flake update
 ```
-As it sounds, this will update your lock file, and commit it.
+As it sounds, this will update your lock file.
 
 ## Updating Package Sources
-If you pass an input name then it will only update that input.
+If you pass directory name then it will update that input if the directory
+contains a flake.nix, with an optional arguement to update only a specific
+input in the subflake.
 
 For example, you can update any
 [package sources](../../pkgs#automatic-source-updates) you may have declared
 in _pkgs/flake.nix_:
 ```sh
-flk update srcs
+flk update pkgs
+```
+or just its _nixpkgs_:
+```sh
+flk update pkgs nixpkgs
 ```

extern/default.nix

@@ -9,11 +9,13 @@ in
   ];
 
   overlays = [
+    nix.overlay
     nur.overlay
     devshell.overlay
     (final: prev: {
       deploy-rs = deploy.packages.${prev.system}.deploy-rs;
     })
+    pkgs.overlay
   ];
 
   # passed to all nixos modules

flake.lock

@@ -152,6 +152,25 @@
         "type": "github"
       }
     },
+    "nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixos"
+        ]
+      },
+      "locked": {
+        "lastModified": 1615476733,
+        "narHash": "sha256-iae4JMAl2KAaPhUGLMf4/DEejWjs5fWfEU1ccVF8s6Q=",
+        "owner": "NixOS",
+        "repo": "nix",
+        "rev": "8127094f767b6caae145bc395a504ca62f30af3e",
+        "type": "github"
+      },
+      "original": {
+        "id": "nix",
+        "type": "indirect"
+      }
+    },
     "nixos": {
       "locked": {
         "lastModified": 1614531331,
@@ -210,6 +229,22 @@
         "type": "indirect"
       }
     },
+    "pkgs": {
+      "inputs": {
+        "nixpkgs": [
+          "nixos"
+        ]
+      },
+      "locked": {
+        "narHash": "sha256-sBVaeGxxs7sk7PodW1mqJbF0CqUqUar0GUdd+OPnZ8o=",
+        "path": "./pkgs",
+        "type": "path"
+      },
+      "original": {
+        "path": "./pkgs",
+        "type": "path"
+      }
+    },
     "pre-commit-hooks-nix": {
       "flake": false,
       "locked": {
@@ -235,25 +270,15 @@
         "flake-compat": "flake-compat",
         "home": "home",
         "naersk": "naersk",
+        "nix": "nix",
         "nixos": "nixos",
         "nixos-hardware": "nixos-hardware",
         "nur": "nur",
         "override": "override",
-        "srcs": "srcs",
+        "pkgs": "pkgs",
         "utils": "utils"
       }
     },
-    "srcs": {
-      "locked": {
-        "narHash": "sha256-Ot96/oKT5+A5kdqkfYyT45cfEiqhI5UyPdEfEZjbXaA=",
-        "path": "./pkgs",
-        "type": "path"
-      },
-      "original": {
-        "path": "./pkgs",
-        "type": "path"
-      }
-    },
     "utils": {
       "locked": {
         "lastModified": 1608663846,

flake.nix

@@ -22,12 +22,14 @@
       home.inputs.nixpkgs.follows = "nixos";
       naersk.url = "github:nmattia/naersk";
       naersk.inputs.nixpkgs.follows = "override";
+      nix.inputs.nixpkgs.follows = "nixos";
       nixos-hardware.url = "github:nixos/nixos-hardware";
       utils.url = "github:numtide/flake-utils/flatten-tree-system";
-      srcs.url = "path:./pkgs";
+      pkgs.url = "path:./pkgs";
+      pkgs.inputs.nixpkgs.follows = "nixos";
     };
 
-  outputs = inputs@{ deploy, nixos, nur, self, utils, ... }:
+  outputs = inputs@{ deploy, nixos, nur, nix, self, utils, ... }:
     let
       inherit (self) lib;
       inherit (lib) os;

lib/devos/mkPkgs.nix

@@ -14,42 +14,6 @@ in
         (overridesOverlay overridePkgs)
         self.overlay
         (final: prev: {
-          srcs =
-            let
-              mkVersion = name: input:
-                let
-                  inputs = (builtins.fromJSON
-                    (builtins.readFile ../../flake.lock)).nodes;
-
-                  ref =
-                    if lib.hasAttrByPath [ name "original" "ref" ] inputs
-                    then inputs.${name}.original.ref
-                    else "";
-
-                  version =
-                    let version' = builtins.match
-                      "[[:alpha:]]*[-._]?([0-9]+(\.[0-9]+)*)+"
-                      ref;
-                    in
-                    if lib.isList version'
-                    then lib.head version'
-                    else if input ? lastModifiedDate && input ? shortRev
-                    then "${lib.substring 0 8 input.lastModifiedDate}_${input.shortRev}"
-                    else null;
-                in
-                version;
-            in
-            lib.mapAttrs
-              (name: input:
-                let
-                  version = mkVersion name input;
-                in
-                input // lib.optionalAttrs (! isNull version)
-                  {
-                    inherit version;
-                  }
-              )
-              self.inputs.srcs.inputs;
           lib = prev.lib.extend (lfinal: lprev: {
             inherit dev;
             inherit (lib) nixosSystem;

overlays/nixFlakes.nix

@@ -1,5 +1,5 @@
 final: prev: {
-  nixFlakes = prev.nixFlakes.overrideAttrs
+  nixFlakes = final.nix.overrideAttrs
     (self:
       let
         oldPatches = self.patches or [ ];

overrides/default.nix

@@ -9,12 +9,12 @@
   # packages pulled from override
   packages = pkgs: final: prev: {
     inherit (pkgs)
+      cachix
       dhall
       discord
       element-desktop
       manix
       nixpkgs-fmt
-      nixFlakes
       qutebrowser
       signal-desktop
       starship;

pkgs/flake.lock

@@ -0,0 +1,25 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1615769536,
+        "narHash": "sha256-oah5pb8kXyFa6ZcccvfREuY9VXHkUTNaoClXW7H1XUw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "63a9f162355ec84c423690869a97848d73409fb8",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

pkgs/flake.nix

@@ -1,7 +1,52 @@
 {
-  description = "Package sources";
+  description = "Package Sources";
 
   inputs = { };
 
-  outputs = { ... }: { };
+  outputs = { self, nixpkgs, ... }: {
+    overlay = final: prev: {
+      inherit (self) srcs;
+    };
+
+    srcs =
+      let
+        inherit (nixpkgs) lib;
+
+        mkVersion = name: input:
+          let
+            inputs = (builtins.fromJSON
+              (builtins.readFile ./flake.lock)).nodes;
+
+            ref =
+              if lib.hasAttrByPath [ name "original" "ref" ] inputs
+              then inputs.${name}.original.ref
+              else "";
+
+            version =
+              let version' = builtins.match
+                "[[:alpha:]]*[-._]?([0-9]+(\.[0-9]+)*)+"
+                ref;
+              in
+              if lib.isList version'
+              then lib.head version'
+              else if input ? lastModifiedDate && input ? shortRev
+              then "${lib.substring 0 8 input.lastModifiedDate}_${input.shortRev}"
+              else null;
+          in
+          version;
+      in
+      lib.mapAttrs
+        (pname: input:
+          let
+            version = mkVersion pname input;
+          in
+          input // { inherit pname; }
+          // lib.optionalAttrs (! isNull version)
+            {
+              inherit version;
+            }
+        )
+        (lib.filterAttrs (n: _: n != "nixpkgs")
+          self.inputs);
+  };
 }

shell/default.nix

@@ -22,6 +22,7 @@ pkgs.devshell.mkShell
     nixos-install
     nixos-generate-config
     nixos-enter
+    pkgs.nixFlakes
   ];
 
   git.hooks = {

shell/devshell.toml

@@ -25,8 +25,5 @@ category = "documentation"
 package = "mdbook"
 category = "documentation"
 
-[[commands]]
-package = "nixFlakes"
-
 [git.hooks]
 enable = true

shell/flk.sh

@@ -50,9 +50,14 @@ case "$1" in
 
   "update")
     if [[ -n "$2" ]]; then
-      nix flake update --update-input "$2" --commit-lock-file "$DEVSHELL_ROOT"
+      if [[ -n "$3" ]]; then
+        (cd $2; nix flake list-inputs --update-input "$3")
       else
-      nix flake update --recreate-lock-file --commit-lock-file "$DEVSHELL_ROOT"
+        (cd $2; nix flake update)
+      fi
+      nix flake list-inputs --update-input "$2" "$DEVSHELL_ROOT"
+    else
+      nix flake update "$DEVSHELL_ROOT"
     fi
     ;;