nix-on-droid: passthrough --override-input arg

`pkgs.system` is now an [alias][1] to `pkgs.stdenv.hostPlatform.system`.

After this it's possible to set `config.allowAliases = false` for nixpkgs:

```
nixOnDroidConfigurations.default = nix-on-droid.lib.nixOnDroidConfiguration {
  pkgs = import nixpkgs { config.allowAliases = false; system = "aarch64-linux"; };
  modules = [ ./nix-on-droid.nix ];
};
```

[1]: 3fa87fea66/pkgs/top-level/aliases.nix (L1386)

.github/workflows/emulator.yml

@@ -14,14 +14,17 @@ jobs:
       path: ${{ steps.droidctl-build.outputs.path }}
     steps:
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-      - name: Configure Nix magic cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
+        uses: nixbuild/nix-quick-install-action@master
+      - name: Configure Nix cache
+        uses: nix-community/cache-nix-action@main
+        with:
+          primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}
 
       - name: Build droidctl
         id: droidctl-build
         run: |
-          nix build 'github:t184256/droidctl' --out-link /tmp/droidctl
+          NIXPKGS_ALLOW_UNFREE=1 nix build --impure 'github:t184256/droidctl' --out-link /tmp/droidctl
           echo "path=$(realpath /tmp/droidctl)" >> "$GITHUB_OUTPUT"
 
 
@@ -30,13 +33,16 @@ jobs:
     timeout-minutes: 10
     steps:
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
+        uses: nixbuild/nix-quick-install-action@master
       - name: Setup cachix
         uses: cachix/cachix-action@v14
         with:
           name: nix-on-droid
-      - name: Configure Nix magic cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
+      - name: Configure Nix cache
+        uses: nix-community/cache-nix-action@main
+        with:
+          primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}
 
       - name: Checkout repository
         uses: actions/checkout@v4
@@ -132,20 +138,23 @@ jobs:
         run: tar xf n-o-d.tar
 
       - name: Install Nix / enable KVM
-        uses: DeterminateSystems/nix-installer-action@main
-      - name: Configure Nix magic cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
+        uses: nixbuild/nix-quick-install-action@master
+      - name: Configure Nix cache
+        uses: nix-community/cache-nix-action@main
+        with:
+          primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
+          restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}
 
       - name: Fetch droidctl (using previous eval)
         id: droidctl-fetch
         env:
           DROIDCTL: ${{needs.prepare-droidctl.outputs.path}}
         run: nix build "$DROIDCTL" --out-link /tmp/droidctl
-        continue-on-error: true  # GitHub Actions can throttle magic-nix-cache
+        continue-on-error: true  # GitHub Actions can throttle cache-nix-action
 
       - name: Build droidctl (anew, fallback)
         if: always() && (steps.droidctl-fetch.outcome == 'failure')
-        run: nix build 'github:t184256/droidctl' --out-link /tmp/droidctl
+        run: NIXPKGS_ALLOW_UNFREE=1 nix build --impure 'github:t184256/droidctl' --out-link /tmp/droidctl
 
       - name: Restore AVD cache
         id: avd-cache

flake.nix

@@ -77,11 +77,11 @@
           # deprecated:
         , config ? null
         , extraModules ? null
-        , system ? null  # pkgs.system is used to detect user's arch
+        , system ? null  # pkgs.stdenv.hostPlatform.system is used to detect user's arch
         }:
-        if ! (builtins.elem pkgs.system [ "aarch64-linux" "x86_64-linux" ]) then
+        if ! (builtins.elem pkgs.stdenv.hostPlatform.system [ "aarch64-linux" "x86_64-linux" ]) then
           throw
-            ("${pkgs.system} is not supported; aarch64-linux / x86_64-linux " +
+            ("${pkgs.stdenv.hostPlatform.system} is not supported; aarch64-linux / x86_64-linux " +
               "are the only currently supported system types")
         else
           pkgs.lib.throwIf
@@ -95,12 +95,12 @@
 
               have been removed.
               Instead of 'extraModules' use the argument 'modules'.
-              The 'system' will be inferred by 'pkgs.system',
+              The 'system' will be inferred by 'pkgs.stdenv.hostPlatform.system',
               so pass a 'pkgs = import nixpkgs { system = "aarch64-linux"; };'
               See the 22.11 release notes for more.
             ''
             (import ./modules {
-              targetSystem = pkgs.system; # system to cross-compile to
+              targetSystem = pkgs.stdenv.hostPlatform.system; # system to cross-compile to
               inherit extraSpecialArgs home-manager-path pkgs;
               config.imports = modules;
               isFlake = true;

modules/user.nix

@@ -28,7 +28,7 @@ in
     user = {
       group = mkOption {
         type = types.str;
-        readOnly = true;
+        default = "nix-on-droid";
         description = "Group name.";
       };
 
@@ -56,7 +56,7 @@ in
 
       userName = mkOption {
         type = types.str;
-        readOnly = true;
+        default = "nix-on-droid";
         description = "User name.";
       };
 
@@ -90,9 +90,7 @@ in
     };
 
     user = {
-      group = "nix-on-droid";
       home = "/data/data/com.termux.nix/files/home";
-      userName = "nix-on-droid";
     };
 
   };

nix-on-droid/nix-on-droid.sh

@@ -68,6 +68,7 @@ function doHelp() {
     echo "  --keep-going"
     echo "  --max-jobs NUM"
     echo "  --option NAME VALUE"
+    echo "  --override-input INPUT URL"
     echo "  --show-trace"
     echo
     echo "Commands"
@@ -162,7 +163,7 @@ while [[ $# -gt 0 ]]; do
         -n|--dry-run)
             export DRY_RUN=1
             ;;
-        --option)
+        --option|--override-input)
             PASSTHROUGH_OPTS+=("$opt" "$1" "$2")
             shift 2
             ;;