nix: Refactor gh-actions and re-enable nightly builds (#31489)

Now that the nix build is working again, re-enable nightly builds and
refactor the workflow for re-use between nightly releases and CI jobs.

Release Notes:

- N/A

---------

Co-authored-by: Rahul Butani <rrbutani@users.noreply.github.com>

.github/workflows/ci.yml

@@ -714,48 +714,12 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
   nix-build:
-    timeout-minutes: 60
-    name: Nix Build
-    continue-on-error: true
+    uses: ./.github/workflows/nix.yml
     if: github.repository_owner == 'zed-industries' && contains(github.event.pull_request.labels.*.name, 'run-nix')
-    strategy:
-      fail-fast: false
-      matrix:
-        system:
-          - os: x86 Linux
-            runner: buildjet-16vcpu-ubuntu-2204
-            install_nix: true
-          - os: arm Mac
-            runner: [macOS, ARM64, test]
-            install_nix: false
-    runs-on: ${{ matrix.system.runner }}
-    env:
-      ZED_CLIENT_CHECKSUM_SEED: ${{ secrets.ZED_CLIENT_CHECKSUM_SEED }}
-      GIT_LFS_SKIP_SMUDGE: 1 # breaks the livekit rust sdk examples which we don't actually depend on
-    steps:
-      - name: Checkout repo
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
-        with:
-          clean: false
-      - name: Set path
-        if: ${{ ! matrix.system.install_nix }}
-        run: |
-          echo "/nix/var/nix/profiles/default/bin" >> $GITHUB_PATH
-          echo "/Users/administrator/.nix-profile/bin" >> $GITHUB_PATH
-
-      - uses: cachix/install-nix-action@d1ca217b388ee87b2507a9a93bf01368bde7cec2 # v31
-        if: ${{ matrix.system.install_nix }}
-        with:
-          github_access_token: ${{ secrets.GITHUB_TOKEN }}
-
-      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
-        with:
-          name: zed-industries
-          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-          skipPush: true
-      - run: nix build .#debug
-      - name: Limit /nix/store to 50GB
-        run: "[ $(du -sm /nix/store | cut -f1) -gt 50000 ] && nix-collect-garbage -d"
+    with:
+      flake-output: debug
+      # excludes the final package to only cache dependencies
+      cachix-filter: "-zed-editor-[0-9.]*-nightly"
 
   auto-release-preview:
     name: Auto release preview

.github/workflows/nix.yml

@@ -0,0 +1,65 @@
+name: "Nix build"
+
+on:
+  workflow_call:
+    inputs:
+      flake-output:
+        type: string
+        default: "default"
+      cachix-filter:
+        type: string
+        default: ""
+
+jobs:
+  nix-build:
+    timeout-minutes: 60
+    name: (${{ matrix.system.os }}) Nix Build
+    continue-on-error: true # TODO: remove when we want this to start blocking CI
+    strategy:
+      fail-fast: false
+      matrix:
+        system:
+          - os: x86 Linux
+            runner: buildjet-16vcpu-ubuntu-2204
+            install_nix: true
+          - os: arm Mac
+            runner: [macOS, ARM64, test]
+            install_nix: false
+    if: github.repository_owner == 'zed-industries'
+    runs-on: ${{ matrix.system.runner }}
+    env:
+      ZED_CLIENT_CHECKSUM_SEED: ${{ secrets.ZED_CLIENT_CHECKSUM_SEED }}
+      ZED_CLOUD_PROVIDER_ADDITIONAL_MODELS_JSON: ${{ secrets.ZED_CLOUD_PROVIDER_ADDITIONAL_MODELS_JSON }}
+      GIT_LFS_SKIP_SMUDGE: 1 # breaks the livekit rust sdk examples which we don't actually depend on
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+        with:
+          clean: false
+
+      # on our macs we manually install nix. for some reason the cachix action is running
+      # under a non-login /bin/bash shell which doesn't source the proper script to add the
+      # nix profile to PATH, so we manually add them here
+      - name: Set path
+        if: ${{ ! matrix.system.install_nix }}
+        run: |
+          echo "/nix/var/nix/profiles/default/bin" >> $GITHUB_PATH
+          echo "/Users/administrator/.nix-profile/bin" >> $GITHUB_PATH
+
+      - uses: cachix/install-nix-action@02a151ada4993995686f9ed4f1be7cfbb229e56f # v31
+        if: ${{ matrix.system.install_nix }}
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
+        with:
+          name: zed
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          pushFilter: "${{ inputs.cachix-filter }}"
+
+      - run: nix build .#${{ inputs.flake-output }} -L --accept-flake-config
+
+      - name: Limit /nix/store to 50GB on macs
+        if: ${{ ! matrix.system.install_nix }}
+        run: |
+          [ $(du -sm /nix/store | cut -f1) -gt 50000 ] && nix-collect-garbage -d || :

.github/workflows/release_nightly.yml

@@ -167,6 +167,10 @@ jobs:
       - name: Upload Zed Nightly
         run: script/upload-nightly linux-targz
 
+  bundle-nix:
+    needs: tests
+    uses: ./.github/workflows/nix.yml
+
   update-nightly-tag:
     name: Update nightly tag
     if: github.repository_owner == 'zed-industries'