introduce a justfile to handle builds

- justfile: init
 - flake: add devShell with just
 - direnv: enable devShell
 - gh-actions: move github actions command from "raw" nix commands to `just` build-*
 - gh-actions: remove all jobs that are not strictly necessary
 - gh-actions: remove all dependencies

.envrc

@@ -0,0 +1 @@
+use flake

.github/workflows/continuous-build.yaml

@@ -16,50 +16,12 @@ on:
 
 env:
   NIXPKGS_RISCV_GHC_BOOTSTRAP_ISSUE: https://github.com/nixos/nixpkgs/issues/231537
+  UPDATE_LOCKFILE: 1
   nix-build-cmd: nix build --print-build-logs --show-trace --max-jobs 1 --cores 0
 
 jobs:
-  nix-flake-update:
+  build-iso:
     runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@main
-      - uses: DeterminateSystems/nix-installer-action@main
-
-      - name: Updating the flake lockfile
-        run: |
-          nix flake update
-
-  cache-build-deps:
-    runs-on: ubuntu-latest
-    needs: nix-flake-update
-    permissions:
-      contents: read
-      id-token: write
-    strategy:
-      fail-fast: false
-      matrix:
-        build_drvs: [ fractal ]
-        linux_arches: [ aarch64, riscv64, x86_64 ]
-
-    steps:
-      - uses: actions/checkout@main
-      - uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: "extra-platforms = aarch64-linux riscv64-linux x86_64-linux"
-      - uses: DeterminateSystems/magic-nix-cache-action@main
-
-      - name: Caching build for ${{ build_drvs }}
-        run: |
-          if [[ '${{ matrix.linux_arches }}' != 'riscv64' ]]; then
-              NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 ${{ env.nix-build-cmd }} --impure nixpkgs#${{ build_drvs }}
-          else
-              echo "RISC-V job for ${{ github.job }} skipped until $NIXPKGS_RISCV_GHC_BOOTSTRAP_ISSUE is resolved."
-          fi
-
-
-  iso:
-    runs-on: ubuntu-latest
-    needs: [ nixos, hm-linux ]
     permissions:
       contents: read
       id-token: write
@@ -74,6 +36,7 @@ jobs:
         with:
           extra-conf: "extra-platforms = aarch64-linux riscv64-linux x86_64-linux"
       - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: taiki-e/install-action@just
 
       - name: Setting up QEMU
         run: |
@@ -84,14 +47,13 @@ jobs:
       - name: Building NixOS ISO for ${{ matrix.linux_arches }}
         run: |
           if [[ '${{ matrix.linux_arches }}' != 'riscv64' ]]; then
-              NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 ${{ env.nix-build-cmd }} --impure .#isos.${{ matrix.linux_arches }}
+              just actual-arch=${{ matrix.linux_arches }} build-iso
           else
               echo "RISC-V job for ${{ github.job }} skipped until $NIXPKGS_RISCV_GHC_BOOTSTRAP_ISSUE is resolved."
           fi
 
-  nixos:
+  build-nixos-system:
     runs-on: ubuntu-latest
-    needs: hm-linux
     permissions:
       contents: read
       id-token: write
@@ -106,6 +68,7 @@ jobs:
         with:
           extra-conf: "extra-platforms = aarch64-linux riscv64-linux x86_64-linux"
       - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: taiki-e/install-action@just
 
       - name: Setting up QEMU
         run: |
@@ -116,14 +79,13 @@ jobs:
       - name: Building NixOS configuration for ${{ matrix.machines }}
         run: |
           if [[ "$(nix eval --raw .#nixosConfigurations.${{ matrix.machines }}.pkgs.stdenv.system)" != 'riscv64-linux' ]]; then
-              NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 ${{ env.nix-build-cmd }} --impure .#machines.${{ matrix.machines }}
+              just actual-arch=emulated nixos-machine-hostname=${{ matrix.machines }} build-nixos-system
           else
               echo "RISC-V job for ${{ github.job }} skipped until $NIXPKGS_RISCV_GHC_BOOTSTRAP_ISSUE is resolved."
           fi
 
-  hm-linux:
+  build-home-manager-linux:
     runs-on: ubuntu-latest
-    needs: cache-build-deps
     permissions:
       contents: read
       id-token: write
@@ -139,6 +101,7 @@ jobs:
         with:
           extra-conf: "extra-platforms = aarch64-linux riscv64-linux x86_64-linux"
       - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: taiki-e/install-action@just
 
       - name: Setting up QEMU
         run: |
@@ -149,14 +112,13 @@ jobs:
       - name: Building home-manager configuration for ${{ matrix.homeOf }}
         run: |
           if [[ '${{ matrix.linux_arches }}' != 'riscv64' ]]; then
-              NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 ${{ env.nix-build-cmd }} --impure .#homeOf.${{ matrix.linux_arches }}-linux.${{ matrix.homeOf }}
+              just actual-arch=${{ matrix.linux_arches }} hm-user=${{ matrix.homeOf }} build-home-manager
           else
               echo "RISC-V job for ${{ github.job }} skipped until $NIXPKGS_RISCV_GHC_BOOTSTRAP_ISSUE is resolved."
           fi
 
-  hm-darwin:
+  build-home-manager-darwin:
     runs-on: macos-latest
-    needs: nix-flake-update
     permissions:
       contents: read
       id-token: write
@@ -169,6 +131,7 @@ jobs:
       - uses: actions/checkout@main
       - uses: DeterminateSystems/nix-installer-action@main
       - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: taiki-e/install-action@just
 
       - name: Building home-manager configuration for ${{ matrix.homeOf }}
         run: |
@@ -180,4 +143,4 @@ jobs:
               echo "well well well, look what we have... Darwin on $(uname -m)"
               exit 1
           fi
-          ${{ env.nix-build-cmd }} .#homeOf."${system_attr}".${{ matrix.homeOf }}
+          just hm-user=${{ matrix.homeOf }} build-home-manager

flake.nix

@@ -238,5 +238,17 @@
       homeOf = forEachSupportedSystem ({ pkgs, ... }: {
         pratham = buildHomeOf pkgs.system "pratham";
       });
+
+      devShells = forEachSupportedSystem ({ pkgs, ... }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [ just ];
+
+          env = {
+            UPDATE_LOCKFILE = 0;
+            USE_NOM_INSTEAD = 1;
+            DO_DRY_RUN = 1;
+          };
+        };
+      });
     };
 }

justfile

@@ -0,0 +1,42 @@
+#!/usr/bin/env just --justfile
+set shell := [ "bash", "-cu"]
+
+actual-os := if os() == "macos" { "darwin" } else { os() }
+actual-arch := env_var_or_default("EMULATED_SYSTEM", arch())
+
+hm-user := env_var_or_default("HM_USER", "pratham")
+nixos-machine-hostname := env_var_or_default("NIXOS_MACHINE_HOSTNAME", "")
+
+update-lockfile := env_var_or_default("UPDATE_LOCKFILE", "0")
+use-nom-instead := env_var_or_default("USE_NOM_INSTEAD", "0")
+do-dry-run := env_var_or_default("DO_DRY_RUN", "0")
+building-for-foreign-arch := if actual-arch == arch() { "0" } else { "1" }
+
+nix-cmd := if use-nom-instead == "1" { "nom" } else { "nix" }
+common-build-args := " --print-build-logs --show-trace --max-jobs 1 --cores 0"
+dry-run-args := if do-dry-run == "1" { " --dry-run" } else { "" }
+foreign-arch-env-var := if building-for-foreign-arch == "0" { "" } else { "NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 " }
+foreign-arch-args := if building-for-foreign-arch == "0" { "" } else { " --impure" }
+nix-build-cmd := foreign-arch-env-var + nix-cmd + " build" + common-build-args + foreign-arch-args + dry-run-args
+
+lockfile-update-cmd := if update-lockfile == "0" { "" } else { "nix flake update" }
+
+[private]
+default:
+    @just --list --unsorted
+
+[private]
+nix-flake-update:
+    {{ lockfile-update-cmd }}
+
+[unix]
+build-home-manager: nix-flake-update
+    {{ nix-build-cmd }} .#legacyPackages.{{ actual-arch }}-{{ actual-os }}.homeConfigurations.{{ hm-user }}.activationPackage
+
+[linux]
+build-nixos-system: nix-flake-update
+    {{ nix-build-cmd }} .#nixosConfigurations.{{ nixos-machine-hostname }}.config.system.build.toplevel
+
+[linux]
+build-iso: nix-flake-update
+    {{ nix-build-cmd }} .#nixosConfigurations.iso-{{ actual-arch }}.config.system.build.isoImage