fix #97: install nix config correctly for single-user- mode

enable flakes & nix-command features by default

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.4.0
     - run: yarn install --frozen-lockfile
     - run: yarn build
     - name: Install Nix
@@ -31,7 +31,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.4.0
     - run: yarn install --frozen-lockfile
     - run: yarn build
     - name: Install Nix
@@ -47,7 +47,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.4.0
     - run: yarn install --frozen-lockfile
     - run: yarn build
     - name: Install Nix
@@ -65,7 +65,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2.3.4
+    - uses: actions/checkout@v2.4.0
     - run: yarn install --frozen-lockfile
     - run: yarn build
     - name: Install Nix
@@ -74,7 +74,6 @@ jobs:
         install_url: https://nixos-nix-install-tests.cachix.org/serve/i6laym9jw3wg9mw6ncyrk6gjx4l34vvx/install
         install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'
         extra_nix_config: |
-          experimental-features = nix-command flakes
           access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
     - run: nix flake show github:NixOS/nixpkgs
 
@@ -84,7 +83,7 @@ jobs:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.4.0
     - run: yarn install --frozen-lockfile
     - run: yarn build
     - name: Install Nix
@@ -94,3 +93,19 @@ jobs:
         install_url: https://nixos-nix-install-tests.cachix.org/serve/i6laym9jw3wg9mw6ncyrk6gjx4l34vvx/install
         install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'
     - run: nix-build test.nix
+
+  oldest-supported-installer:
+    strategy:
+        matrix:
+          os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v2.3.5
+    - run: yarn install --frozen-lockfile
+    - run: yarn build
+    - name: Install Nix
+      uses: ./
+      with:
+        nix_path: nixpkgs=channel:nixos-21.05
+        install_url: https://releases.nixos.org/nix/nix-2.3.5/install
+    - run: nix-build test.nix

README.md

@@ -14,10 +14,11 @@ or [pin nixpkgs yourself](https://nix.dev/reference/pinning-nixpkgs.html)
 - Quick installation (~4s on Linux, ~20s on macOS)
 - Multi-User installation (with sandboxing enabled only on Linux)
 - [Self-hosted github runner](https://docs.github.com/en/actions/hosting-your-own-runners/about-self-hosted-runners) support
-- Allows specifying Nix installation URL via `install_url`
+- Allows specifying Nix installation URL via `install_url` (the oldest supported Nix version is 2.3.5)
 - Allows specifying extra Nix configration options via `extra_nix_config`
 - Allows specifying `$NIX_PATH` and channels via `nix_path`
 - Share `/nix/store` between builds using [cachix-action](https://github.com/cachix/cachix-action) for simple binary cache setup to speed up your builds and share binaries with your team
+- Enables `flakes` and `nix-command` experimental features by default (to disable, set ``experimental-features` via `extra_nix_config`) 
 
 ## Usage
 
@@ -33,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2.3.4
-    - uses: cachix/install-nix-action@v13
+    - uses: cachix/install-nix-action@v14.1
       with:
         nix_path: nixpkgs=channel:nixos-unstable
     - run: nix-build
@@ -52,12 +53,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2.3.4
-    - uses: cachix/install-nix-action@v13
+    - uses: cachix/install-nix-action@v14.1
       with:
-        install_url: https://nixos-nix-install-tests.cachix.org/serve/i6laym9jw3wg9mw6ncyrk6gjx4l34vvx/install
+        install_url: https://nixos-nix-install-tests.cachix.org/serve/vij683ly7sl95nnhb67bdjjfabclr85m/install
         install_options: '--tarball-url-prefix https://nixos-nix-install-tests.cachix.org/serve'
         extra_nix_config: |
-          experimental-features = nix-command flakes
           access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
     - run: nix build
     - run: nix flake check

lib/install-nix.sh

@@ -18,6 +18,9 @@ add_config "trusted-users = root $USER"
 if [[ $INPUT_EXTRA_NIX_CONFIG != "" ]]; then
   add_config "$INPUT_EXTRA_NIX_CONFIG"
 fi
+if [[ ! $INPUT_EXTRA_NIX_CONFIG =~ "experimental-features" ]]; then  
+  add_config "experimental-features = nix-command flakes"
+fi
 
 # Nix installer flags
 installer_options=(
@@ -35,8 +38,7 @@ if [[ $OSTYPE =~ darwin || -e /run/systemd/system ]]; then
 else
   # "fix" the following error when running nix*
   # error: the group 'nixbld' specified in 'build-users-group' does not exist
-  mkdir -m 0755 /etc/nix
+  add_config "build-users-group ="
-  echo "build-users-group =" > /etc/nix/nix.conf
 fi
 
 if [[ $INPUT_INSTALL_OPTIONS != "" ]]; then
@@ -48,9 +50,6 @@ echo "installer options: ${installer_options[@]}"
 sh <(curl --retry 5 --retry-connrefused -L "${INPUT_INSTALL_URL:-https://nixos.org/nix/install}") "${installer_options[@]}"
 
 if [[ $OSTYPE =~ darwin ]]; then
-  # Disable spotlight indexing of /nix to speed up performance
-  sudo mdutil -i off /nix
-
   # macOS needs certificates hints
   cert_file=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt
   echo "NIX_SSL_CERT_FILE=$cert_file" >> "$GITHUB_ENV"

yarn.lock

@@ -3307,9 +3307,9 @@ throat@^4.0.0:
   integrity sha1-iQN8vJLFarGJJua6TLsgDhVnKmo=
 
 tmpl@1.0.x:
-  version "1.0.4"
+  version "1.0.5"
-  resolved "https://registry.yarnpkg.com/tmpl/-/tmpl-1.0.4.tgz#23640dd7b42d00433911140820e5cf440e521dd1"
+  resolved "https://registry.yarnpkg.com/tmpl/-/tmpl-1.0.5.tgz#8683e0b902bb9c20c4f726e3c0b69f36518c07cc"
-  integrity sha1-I2QN17QtAEM5ERQIIOXPRA5SHdE=
+  integrity sha512-3f0uOEAQwIqGuWW2MVzYg8fV/QNnc/IpuJNG837rLuczAaLVHslWHZQj4IGiEl5Hs3kkbhwL9Ab7Hrsmuj+Smw==
 
 to-fast-properties@^2.0.0:
   version "2.0.0"