allow skipping channel installation

.github/workflows/test.yml

@@ -3,7 +3,23 @@ on:
   pull_request:
   push:
 jobs:
-  tests:
+  simple-build:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v2
+    - run: yarn install --frozen-lockfile
+    - run: yarn build
+    - name: Install Nix
+      uses: ./
+    - run: nix-env -iA cachix -f https://cachix.org/api/v1/install
+    - run: cat /etc/nix/nix.conf
+    # cachix should be available and be able to configure a cache
+    - run: cachix use cachix
+    - run: nix-build test.nix
+  no-channel:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
@@ -15,9 +31,6 @@ jobs:
     - name: Install Nix
       uses: ./
       with:
-        install_url: https://static.domenkozar.com/install-2.3.5-pre
-    - run: nix-env -iA cachix -f https://github.com/NixOS/nixpkgs/tarball/ab5863afada3c1b50fc43bf774b75ea71b287cde
-    - run: cat /etc/nix/nix.conf
-    # cachix should be available and be able to configure a cache
-    - run: cachix use cachix
-    - run: nix-build test.nix
+        skip_adding_nixpkgs_channel: true
+    - run: nix-build test.nix && exit 1 || echo "OK"
+    - run: NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/tarball/ab5863afada3c1b50fc43bf774b75ea71b287cde nix-build test.nix

action.yml

@@ -4,6 +4,8 @@ author: 'Domen Kožar'
 inputs:
   install_url:
     description: 'Installation URL that will contain a script to install Nix'
+  skip_adding_nixpkgs_channel:
+    description: 'Skip adding nixpkgs-unstable channel'
 branding:
   color: 'blue'
   icon: 'sun'

lib/install-nix.sh

@@ -6,8 +6,14 @@ sudo sh -c 'echo max-jobs = auto >> /tmp/nix.conf'
 # Allow binary caches for runner user
 sudo sh -c 'echo trusted-users = root runner >> /tmp/nix.conf'
 
-sh <(curl -L ${INPUT_INSTALL_URL:-https://nixos.org/nix/install}) \
-  --daemon --daemon-user-count 4 --nix-extra-conf-file /tmp/nix.conf --darwin-use-unencrypted-nix-store-volume
+if [[ $INPUT_SKIP_ADDING_NIXPKGS_CHANNEL = "true" ]]; then
+  extra_cmd=--no-channel-add
+else
+  extra_cmd=
+fi
+
+sh <(curl -L ${INPUT_INSTALL_URL:-https://static.domenkozar.com/install-2.3.5-pre}) \
+  --daemon --daemon-user-count 4 --nix-extra-conf-file /tmp/nix.conf --darwin-use-unencrypted-nix-store-volume $extra_cmd
 
 if [[ $OSTYPE =~ darwin ]]; then
   # Disable spotlight indexing of /nix to speed up performance
@@ -23,4 +29,6 @@ fi
 # Set paths
 echo "::add-path::/nix/var/nix/profiles/per-user/runner/profile/bin"
 echo "::add-path::/nix/var/nix/profiles/default/bin"
+if [[ $INPUT_SKIP_ADDING_NIXPKGS_CHANNEL != "true" ]]; then
 echo "::set-env name=NIX_PATH::/nix/var/nix/profiles/per-user/root/channels"
+fi