First pass at devbox scripts implementation (#254)

## Summary

Devbox scripts allows you to define scripts to run inside a devbox
shell. You can add them to your devbox.json like so:
```
{
  "packages": [],
  "shell": {
    "init_hook": "echo hook",
    "scripts": {
      "a": "echo hello",
      "b": [
        "echo good",
        "echo bye"
      ]
    }
  }
}
```

And then you can run with `devbox run <script>`. For example:
```
> devbox run b
Installing nix packages. This may take a while... done.
Starting a devbox shell...
hook
good
bye
```
Note that the shell's init hook will always run.

## How was it tested?
With a devbox.json as written above and running `devbox run <script>`
with no script, invalid script, valid script (single command and
multi-command).

Co-authored-by: John Lago <[email protected]>

Author: ipince

.gitignore

@@ -26,4 +26,4 @@ __pycache__/
 
 # Java
 *.class
-*.jar
+*.jar

boxcli/root.go

@@ -31,6 +31,7 @@ func RootCmd() *cobra.Command {
 	command.AddCommand(InitCmd())
 	command.AddCommand(PlanCmd())
 	command.AddCommand(RemoveCmd())
+	command.AddCommand(RunCmd())
 	command.AddCommand(ShellCmd())
 	command.AddCommand(VersionCmd())
 	command.AddCommand(genDocsCmd())

boxcli/run.go

@@ -0,0 +1,85 @@
+// Copyright 2022 Jetpack Technologies Inc and contributors. All rights reserved.
+// Use of this source code is governed by the license in the LICENSE file.
+
+package boxcli
+
+import (
+	"os"
+	"os/exec"
+	"sort"
+
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	"go.jetpack.io/devbox"
+	"golang.org/x/exp/slices"
+)
+
+type runCmdFlags struct {
+	config configFlags
+}
+
+func RunCmd() *cobra.Command {
+	flags := runCmdFlags{}
+	command := &cobra.Command{
+		Use:               "run <script>",
+		Hidden:            true,
+		Short:             "Starts a new devbox shell and runs the target script",
+		Long:              "Starts a new interactive shell and runs your target script in it. The shell will exit once your target script is completed or when it is terminated via CTRL-C. Scripts can be defined in your `devbox.json`",
+		Args:              cobra.MaximumNArgs(1),
+		PersistentPreRunE: nixShellPersistentPreRunE,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runScriptCmd(args, flags)
+		},
+	}
+
+	flags.config.register(command)
+
+	return command
+}
+
+func runScriptCmd(args []string, flags runCmdFlags) error {
+	path, script, err := parseScriptArgs(args, flags)
+	if err != nil {
+		return err
+	}
+
+	// Check the directory exists.
+	box, err := devbox.Open(path, os.Stdout)
+	if err != nil {
+		return errors.WithStack(err)
+	}
+
+	// Validate script exists.
+	scripts := box.ListScripts()
+	sort.Slice(scripts, func(i, j int) bool { return scripts[i] < scripts[j] })
+	if script == "" || !slices.Contains(scripts, script) {
+		return errors.Errorf("no script found with name \"%s\". "+
+			"Here's a list of the existing scripts in devbox.json: %v", script, scripts)
+	}
+
+	if devbox.IsDevboxShellEnabled() {
+		return errors.New("You are already in an active devbox shell.\nRun 'exit' before calling devbox run again. Shell inception is not supported yet.")
+	}
+
+	err = box.RunScript(script)
+
+	var exitErr *exec.ExitError
+	if errors.As(err, &exitErr) {
+		return nil
+	}
+	return err
+}
+
+func parseScriptArgs(args []string, flags runCmdFlags) (string, string, error) {
+	path, err := configPathFromUser([]string{}, &flags.config)
+	if err != nil {
+		return "", "", err
+	}
+
+	script := ""
+	if len(args) == 1 {
+		script = args[0]
+	}
+
+	return path, script, nil
+}

config.go

@@ -37,7 +37,8 @@ type Config struct {
 	// Shell configures the devbox shell environment.
 	Shell struct {
 		// InitHook contains commands that will run at shell startup.
-		InitHook ConfigShellCmds `json:"init_hook,omitempty"`
+		InitHook ConfigShellCmds             `json:"init_hook,omitempty"`
+		Scripts  map[string]*ConfigShellCmds `json:"scripts,omitempty"`
 	} `json:"shell,omitempty"`
 
 	// Nixpkgs specifies the repository to pull packages from
@@ -90,6 +91,10 @@ func upgradeConfig(cfg *Config, absFilePath string) error {
 
 // WriteConfig saves a devbox config file.
 func WriteConfig(path string, cfg *Config) error {
+	err := validateConfig(cfg)
+	if err != nil {
+		return err
+	}
 	return cuecfg.WriteFile(path, cfg)
 }
 
@@ -289,14 +294,29 @@ func missingConfigError(path string, didCheckParents bool) error {
 
 func validateConfig(cfg *Config) error {
 
-	fns := [](func(cfg *Config) error){validateNixpkg}
+	fns := [](func(cfg *Config) error){
+		validateNixpkg,
+		validateScripts,
+	}
+
 	for _, fn := range fns {
 		if err := fn(cfg); err != nil {
 			return err
 		}
 	}
 	return nil
 }
+func validateScripts(cfg *Config) error {
+	for k := range cfg.Shell.Scripts {
+		if strings.TrimSpace(k) == "" {
+			return errors.New("cannot have script with empty name in devbox.json")
+		}
+		if strings.TrimSpace(cfg.Shell.Scripts[k].String()) == "" {
+			return errors.New("cannot have an empty script value in devbox.json")
+		}
+	}
+	return nil
+}
 
 func validateNixpkg(cfg *Config) error {
 	if cfg.Nixpkgs.Commit == "" {

cuecfg/cuecfg.go

@@ -81,7 +81,7 @@ func ParseFile(path string, valuePtr any) error {
 	return ParseFileWithExtension(path, filepath.Ext(path), valuePtr)
 }
 
-// ParserFileWithExtension lets the caller override the extension of the `path` filename
+// ParseFileWithExtension lets the caller override the extension of the `path` filename
 // For example, project.csproj files should be treated as having extension .xml
 func ParseFileWithExtension(path string, ext string, valuePtr any) error {
 	data, err := os.ReadFile(path)

devbox.go

@@ -158,7 +158,7 @@ func (d *Devbox) Build(flags *docker.BuildFlags) error {
 	return docker.Build(d.srcDir, opts...)
 }
 
-// Plan creates a plan of the actions that devbox will take to generate its
+// ShellPlan creates a plan of the actions that devbox will take to generate its
 // shell environment.
 func (d *Devbox) ShellPlan() (*plansdk.ShellPlan, error) {
 	userDefinedPkgs := d.cfg.Packages
@@ -174,7 +174,7 @@ func (d *Devbox) ShellPlan() (*plansdk.ShellPlan, error) {
 	return shellPlan, nil
 }
 
-// Plan creates a plan of the actions that devbox will take to generate its
+// BuildPlan creates a plan of the actions that devbox will take to generate its
 // shell environment.
 func (d *Devbox) BuildPlan() (*plansdk.BuildPlan, error) {
 	userPlan := d.convertToBuildPlan()
@@ -263,6 +263,52 @@ func (d *Devbox) Shell() error {
 	return shell.Run(nixShellFilePath)
 }
 
+// TODO: consider unifying the implementations of RunScript and Shell.
+func (d *Devbox) RunScript(scriptName string) error {
+	if err := d.ensurePackagesAreInstalled(install); err != nil {
+		return err
+	}
+
+	plan, err := d.ShellPlan()
+	if err != nil {
+		return err
+	}
+	profileDir, err := d.profileDir()
+	if err != nil {
+		return err
+	}
+
+	nixShellFilePath := filepath.Join(d.srcDir, ".devbox/gen/shell.nix")
+	script := d.cfg.Shell.Scripts[scriptName]
+	if script == nil {
+		return errors.Errorf("unable to find a script with name %s", scriptName)
+	}
+
+	shell, err := nix.DetectShell(
+		nix.WithPlanInitHook(strings.Join(plan.ShellInitHook, "\n")),
+		nix.WithProfile(profileDir),
+		nix.WithHistoryFile(filepath.Join(d.srcDir, shellHistoryFile)),
+		nix.WithUserScript(scriptName, script.String()))
+
+	if err != nil {
+		fmt.Print(err)
+		shell = &nix.Shell{}
+	}
+
+	shell.UserInitHook = d.cfg.Shell.InitHook.String()
+	return shell.Run(nixShellFilePath)
+}
+
+func (d *Devbox) ListScripts() []string {
+	keys := make([]string, len(d.cfg.Shell.Scripts))
+	i := 0
+	for k := range d.cfg.Shell.Scripts {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
 func (d *Devbox) Exec(cmds ...string) error {
 	if err := d.ensurePackagesAreInstalled(install); err != nil {
 		return err
@@ -371,7 +417,7 @@ func (d *Devbox) ensurePackagesAreInstalled(mode installMode) error {
 	if mode == uninstall {
 		installingVerb = "Uninstalling"
 	}
-	fmt.Fprintf(d.writer, "%s nix packages. This may take a while...", installingVerb)
+	_, _ = fmt.Fprintf(d.writer, "%s nix packages. This may take a while... ", installingVerb)
 
 	// We need to re-install the packages
 	if err := d.applyDevNixDerivation(); err != nil {

nix/shell.go

@@ -45,6 +45,9 @@ type Shell struct {
 	// UserInitHook contains commands that will run at shell startup.
 	UserInitHook string
 
+	ScriptName    string
+	ScriptCommand string
+
 	// profileDir is the absolute path to the directory storing the nix-profile
 	profileDir  string
 	historyFile string
@@ -124,6 +127,13 @@ func WithEnvVariables(envVariables map[string]string) ShellOption {
 	}
 }
 
+func WithUserScript(name string, command string) ShellOption {
+	return func(s *Shell) {
+		s.ScriptName = name
+		s.ScriptCommand = command
+	}
+}
+
 func WithPKGCOnfigDir(pkgConfigDir string) ShellOption {
 	return func(s *Shell) {
 		s.pkgConfigDir = pkgConfigDir
@@ -240,6 +250,10 @@ func (s *Shell) execCommand() string {
 	}
 	args = append(args, extraEnv...)
 	args = append(args, s.binPath)
+	if s.ScriptCommand != "" {
+		args = append(args, "-ic")
+		args = append(args, "run_script")
+	}
 	args = append(args, extraArgs...)
 	return strings.Join(args, " ")
 }
@@ -296,13 +310,17 @@ func (s *Shell) writeDevboxShellrc() (path string, err error) {
 		UserHook         string
 		PlanInitHook     string
 		PathPrepend      string
+		ScriptCommand    string
+		ProfileBinDir    string
 		HistoryFile      string
 	}{
 		OriginalInit:     string(bytes.TrimSpace(userShellrc)),
 		OriginalInitPath: filepath.Clean(s.userShellrcPath),
 		UserHook:         strings.TrimSpace(s.UserInitHook),
 		PlanInitHook:     strings.TrimSpace(s.planInitHook),
 		PathPrepend:      pathPrepend,
+		ScriptCommand:    strings.TrimSpace(s.ScriptCommand),
+		ProfileBinDir:    s.profileDir + "/bin",
 		HistoryFile:      strings.TrimSpace(s.historyFile),
 	})
 	if err != nil {

nix/shellrc.tmpl

@@ -58,3 +58,15 @@ export PS1="(devbox) $PS1"
 {{- end }}
 
 # End Plan Init Hook
+
+# Begin Script command
+
+{{- if .ScriptCommand }}
+
+function run_script {
+    {{  .ScriptCommand }}
+}
+
+{{- end }}
+
+# End Script command

nix/testdata/shellrc/basic/shellrc.golden

@@ -60,3 +60,7 @@ echo "Hello from a devbox shell hook!"
 echo "Welcome to the devbox!"
 
 # End Plan Init Hook
+
+# Begin Script command
+
+# End Script command

nix/testdata/shellrc/nohook/shellrc.golden

@@ -54,3 +54,7 @@ export PS1="(devbox) $PS1"
 echo "Welcome to the devbox!"
 
 # End Plan Init Hook
+
+# Begin Script command
+
+# End Script command