[nix profile list] parse using --json in new nix version (#1308)

## Summary

Problem:
Latest nix version of 2.17 changes the output format of `nix profile
list` to be:
```
Index:              0
Flake attribute:    legacyPackages.aarch64-linux.curl
Original flake URL: github:NixOS/nixpkgs/3c614fbc76fc152f3e1bc4b2263da6d90adf80fb
Locked flake URL:   github:NixOS/nixpkgs/3c614fbc76fc152f3e1bc4b2263da6d90adf80fb
Store paths:        /nix/store/3qcvhxxmgcdj6izfs8d3m8csdlsj92ng-curl-8.1.1-bin /nix/store/6skgivna073ziw95xvbksvd5c8n5vi5w-curl-8.1.1-man
```
Previously, the "keys" didn't exist in the output. This broke how we
were parsing the output.

Fix in pseudo code:
```
try invoke: nix profile list --json
if error:
  do old code: nix profile list
```

the older nix versions don't support --json

## How was it tested?

in some devbox projects:
```
# clear old state
> rm -rf .devbox

> devbox shell

# run some commands specific to that project
```

Author: savil

internal/nix/nixprofile/profile.go

@@ -5,6 +5,7 @@ package nixprofile
 
 import (
 	"bufio"
+	"encoding/json"
 	"fmt"
 	"io"
 	"strconv"
@@ -14,9 +15,8 @@ import (
 	"github.com/pkg/errors"
 	"go.jetpack.io/devbox/internal/boxcli/usererr"
 	"go.jetpack.io/devbox/internal/devpkg"
-	"go.jetpack.io/devbox/internal/nix"
-
 	"go.jetpack.io/devbox/internal/lock"
+	"go.jetpack.io/devbox/internal/nix"
 	"go.jetpack.io/devbox/internal/redact"
 )
 
@@ -26,11 +26,49 @@ func ProfileListItems(
 	profileDir string,
 ) (map[string]*NixProfileListItem, error) {
 
-	lines, err := nix.ProfileList(writer, profileDir)
+	output, err := nix.ProfileList(writer, profileDir, true /*useJSON*/)
+	if err == nil {
+		type ProfileListElement struct {
+			Active      bool     `json:"active"`
+			AttrPath    string   `json:"attrPath"`
+			OriginalURL string   `json:"originalUrl"`
+			Priority    int      `json:"priority"`
+			StorePaths  []string `json:"storePaths"`
+			URL         string   `json:"url"`
+		}
+		type ProfileListOutput struct {
+			Elements []ProfileListElement `json:"elements"`
+			Version  int                  `json:"version"`
+		}
+
+		var structOutput ProfileListOutput
+		if err := json.Unmarshal([]byte(output), &structOutput); err != nil {
+			return nil, err
+		}
+
+		result := map[string]*NixProfileListItem{}
+		for index, element := range structOutput.Elements {
+			// We use the unlocked reference as the key, since that is the format
+			// used for the `nix profile list` output of older nix versions
+			// (pre 2.17), which our code is designed to support.
+			unlockedReference := element.OriginalURL + "#" + element.AttrPath
+			result[unlockedReference] = &NixProfileListItem{
+				index:             index,
+				unlockedReference: unlockedReference,
+				lockedReference:   element.URL + "#" + element.AttrPath,
+				nixStorePath:      element.StorePaths[0],
+			}
+		}
+		return result, nil
+	}
+
+	output, err = nix.ProfileList(writer, profileDir, false /*useJSON*/)
 	if err != nil {
-		return nil, err
+		return nil, errors.WithStack(err)
 	}
 
+	lines := strings.Split(output, "\n")
+
 	// The `line` output is of the form:
 	// <index> <UnlockedReference> <LockedReference> <NixStorePath>
 	//
@@ -40,6 +78,10 @@ func ProfileListItems(
 
 	items := map[string]*NixProfileListItem{}
 	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
 		item, err := parseNixProfileListItem(line)
 		if err != nil {
 			return nil, err
@@ -133,6 +175,7 @@ func parseNixProfileListItem(line string) (*NixProfileListItem, error) {
 	if !scanner.Scan() {
 		return nil, redact.Errorf("error parsing \"nix profile list\" output: line is missing index: %s", line)
 	}
+
 	index, err := strconv.Atoi(scanner.Text())
 	if err != nil {
 		return nil, redact.Errorf("error parsing \"nix profile list\" output: %w: %s", err, line)

internal/nix/profiles.go

@@ -4,7 +4,6 @@
 package nix
 
 import (
-	"bufio"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -17,36 +16,16 @@ import (
 	"go.jetpack.io/devbox/internal/redact"
 )
 
-func ProfileList(writer io.Writer, profilePath string) ([]string, error) {
-
+func ProfileList(writer io.Writer, profilePath string, useJSON bool) (string, error) {
 	cmd := command("profile", "list", "--profile", profilePath)
-	cmd.Args = append(cmd.Args, ExperimentalFlags()...)
-
-	// We set stderr to a different output than stdout
-	// to ensure error output is not mingled with the stdout output
-	// that we need to parse.
-	cmd.Stderr = writer
-
-	out, err := cmd.StdoutPipe()
-	if err != nil {
-		return nil, redact.Errorf("error creating stdout pipe: %w", redact.Safe(err))
-	}
-	if err := cmd.Start(); err != nil {
-		return nil, redact.Errorf("error starting \"nix profile list\" command: %w", err)
+	if useJSON {
+		cmd.Args = append(cmd.Args, "--json")
 	}
-
-	scanner := bufio.NewScanner(out)
-	scanner.Split(bufio.ScanLines)
-
-	lines := []string{}
-	for scanner.Scan() {
-		lines = append(lines, scanner.Text())
-	}
-
-	if err := cmd.Wait(); err != nil {
-		return nil, redact.Errorf("error running \"nix profile list\": %w", err)
+	out, err := cmd.Output()
+	if err != nil {
+		return "", redact.Errorf("error running \"nix profile list\": %w", err)
 	}
-	return lines, nil
+	return string(out), nil
 }
 
 func ProfileInstall(writer io.Writer, profilePath string, installable string) error {