Derive nix profile from the generated flake

.github/workflows/cli-tests.yaml

@@ -129,9 +129,8 @@ jobs:
         run-project-tests: ["project-tests", "project-tests-off"]
         # Run tests on:
         # 1. the oldest supported nix version (which is 2.9.0? But determinate-systems installer has 2.12.0)
-        # 2. nix version 2.17.0 which introduces a new code path that minimizes nixpkgs downloads.
-        # 3. latest nix version
-        nix-version: ["2.12.0", "2.17.0", "2.19.2"]
+        # 2. latest nix version, must be > 2.17.0 which introduces a new code path that minimizes nixpkgs downloads.
+        nix-version: ["2.12.0", "2.19.2"]
         exclude:
           - is-main: "not-main"
             os: "${{ inputs.run-mac-tests && 'dummy' || 'macos-latest' }}"

internal/devbox/nixprofile.go

@@ -0,0 +1,74 @@
+package devbox
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/samber/lo"
+	"go.jetpack.io/devbox/internal/nix"
+	"go.jetpack.io/devbox/internal/nix/nixprofile"
+	"go.jetpack.io/devbox/internal/ux"
+)
+
+// syncNixProfile ensures the nix profile has the packages specified in wantStorePaths.
+// It also removes any packages from the nix profile that are not in wantStorePaths.
+func (d *Devbox) syncNixProfile(ctx context.Context, wantStorePaths []string) error {
+	profilePath, err := d.profilePath()
+	if err != nil {
+		return err
+	}
+
+	// Get the store-paths of the packages currently installed in the nix profile
+	items, err := nixprofile.ProfileListItems(ctx, d.stderr, profilePath)
+	if err != nil {
+		return fmt.Errorf("nix profile list: %v", err)
+	}
+	gotStorePaths := make([]string, 0, len(items))
+	for _, item := range items {
+		gotStorePaths = append(gotStorePaths, item.StorePaths()...)
+	}
+
+	// Diff the store paths and install/remove packages as needed
+	remove, add := lo.Difference(gotStorePaths, wantStorePaths)
+	if len(remove) > 0 {
+		packagesToRemove := make([]string, 0, len(remove))
+		for _, p := range remove {
+			storePath := nix.NewStorePathParts(p)
+			packagesToRemove = append(packagesToRemove, fmt.Sprintf("%s@%s", storePath.Name, storePath.Version))
+		}
+		if len(packagesToRemove) == 1 {
+			ux.Finfo(d.stderr, "Removing %s\n", strings.Join(packagesToRemove, ", "))
+		} else {
+			ux.Finfo(d.stderr, "Removing packages: %s\n", strings.Join(packagesToRemove, ", "))
+		}
+
+		if err := nix.ProfileRemove(profilePath, remove...); err != nil {
+			return err
+		}
+	}
+	if len(add) > 0 {
+		total := len(add)
+		for idx, addPath := range add {
+			stepNum := idx + 1
+			storePath := nix.NewStorePathParts(addPath)
+			nameAndVersion := fmt.Sprintf("%s@%s", storePath.Name, storePath.Version)
+			stepMsg := fmt.Sprintf("[%d/%d] %s", stepNum, total, nameAndVersion)
+
+			if err = nixprofile.ProfileInstall(ctx, &nixprofile.ProfileInstallArgs{
+				CustomStepMessage: stepMsg,
+				Installable:       addPath,
+				// Install in offline mode for speed. We know we should have all the files
+				// locally in /nix/store since we have run `nix print-dev-env` prior to this.
+				// Also avoids some "substituter not found for store-path" errors.
+				Offline:     true,
+				PackageName: storePath.Name,
+				ProfilePath: profilePath,
+				Writer:      d.stderr,
+			}); err != nil {
+				return fmt.Errorf("error installing package %s: %w", addPath, err)
+			}
+		}
+	}
+	return nil
+}