[RFC][direnv-inspired] introduce export and hook commands, use in devbox shell, global and direnv

devbox.go

@@ -21,6 +21,7 @@ type Devbox interface {
 	// Adding duplicate packages is a no-op.
 	Add(ctx context.Context, pkgs ...string) error
 	Config() *devconfig.Config
+	ExportHook(shellName string) (string, error)
 	ProjectDir() string
 	// Generate creates the directory of Nix files and the Dockerfile that define
 	// the devbox environment.

internal/boxcli/export.go

@@ -0,0 +1,30 @@
+package boxcli
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// exportCmd is an alias of shellenv, but is also hidden and hence we cannot define it
+// simply using `Aliases: []string{"export"}` in the shellEnvCmd definition.
+func exportCmd() *cobra.Command {
+	flags := shellEnvCmdFlags{}
+	cmd := &cobra.Command{
+		Use:    "export [shell]",
+		Hidden: true,
+		Short:  "Print shell command to setup the shell export to ensure an up-to-date environment",
+		Args:   cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			s, err := shellEnvFunc(cmd, flags)
+			if err != nil {
+				return err
+			}
+			fmt.Fprintln(cmd.OutOrStdout(), s)
+			return nil
+		},
+	}
+
+	registerShellEnvFlags(cmd, &flags)
+	return cmd
+}

internal/boxcli/featureflag/prompt_hook.go

@@ -0,0 +1,5 @@
+package featureflag
+
+// PromptHook controls the insertion of a shell prompt hook that invokes
+// devbox shellenv, in lieu of using binary wrappers.
+var PromptHook = disabled("PROMPT_HOOK")

internal/boxcli/global.go

@@ -26,6 +26,7 @@ func globalCmd() *cobra.Command {
 	}
 
 	addCommandAndHideConfigFlag(globalCmd, addCmd())
+	addCommandAndHideConfigFlag(globalCmd, hookCmd())
 	addCommandAndHideConfigFlag(globalCmd, installCmd())
 	addCommandAndHideConfigFlag(globalCmd, pathCmd())
 	addCommandAndHideConfigFlag(globalCmd, pullCmd())
@@ -112,7 +113,10 @@ func setGlobalConfigForDelegatedCommands(
 }
 
 func ensureGlobalEnvEnabled(cmd *cobra.Command, args []string) error {
-	if cmd.Name() == "shellenv" {
+	// Skip checking this for shellenv and hook sub-commands of devbox global
+	// since these commands are what will enable the global environment when
+	// invoked from the user's shellrc
+	if cmd.Name() == "shellenv" || cmd.Name() == "hook" {
 		return nil
 	}
 	path, err := ensureGlobalConfig(cmd)

internal/boxcli/hook.go

@@ -0,0 +1,41 @@
+package boxcli
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"go.jetpack.io/devbox"
+	"go.jetpack.io/devbox/internal/impl/devopt"
+)
+
+type hookFlags struct {
+	config configFlags
+}
+
+func hookCmd() *cobra.Command {
+	flags := hookFlags{}
+	cmd := &cobra.Command{
+		Use:   "hook [shell]",
+		Short: "Print shell command to setup the shell hook to ensure an up-to-date environment",
+		Args:  cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			output, err := hookFunc(cmd, args, flags)
+			if err != nil {
+				return err
+			}
+			fmt.Fprint(cmd.OutOrStdout(), output)
+			return nil
+		},
+	}
+
+	flags.config.register(cmd)
+	return cmd
+}
+
+func hookFunc(cmd *cobra.Command, args []string, flags hookFlags) (string, error) {
+	box, err := devbox.Open(&devopt.Opts{Dir: flags.config.path, Writer: cmd.ErrOrStderr()})
+	if err != nil {
+		return "", err
+	}
+	return box.ExportHook(args[0])
+}

internal/boxcli/root.go

@@ -52,8 +52,10 @@ func RootCmd() *cobra.Command {
 		command.AddCommand(authCmd())
 	}
 	command.AddCommand(createCmd())
+	command.AddCommand(exportCmd())
 	command.AddCommand(generateCmd())
 	command.AddCommand(globalCmd())
+	command.AddCommand(hookCmd())
 	command.AddCommand(infoCmd())
 	command.AddCommand(initCmd())
 	command.AddCommand(installCmd())

internal/boxcli/shellenv.go

@@ -36,6 +36,14 @@ func shellEnvCmd() *cobra.Command {
 		},
 	}
 
+	registerShellEnvFlags(command, &flags)
+	command.AddCommand(shellEnvOnlyPathWithoutWrappersCmd())
+
+	return command
+}
+
+func registerShellEnvFlags(command *cobra.Command, flags *shellEnvCmdFlags) {
+
 	command.Flags().BoolVar(
 		&flags.runInitHook, "init-hook", false, "runs init hook after exporting shell environment")
 	command.Flags().BoolVar(
@@ -45,10 +53,6 @@ func shellEnvCmd() *cobra.Command {
 		&flags.pure, "pure", false, "If this flag is specified, devbox creates an isolated environment inheriting almost no variables from the current environment. A few variables, in particular HOME, USER and DISPLAY, are retained.")
 
 	flags.config.register(command)
-
-	command.AddCommand(shellEnvOnlyPathWithoutWrappersCmd())
-
-	return command
 }
 
 func shellEnvFunc(cmd *cobra.Command, flags shellEnvCmdFlags) (string, error) {

internal/impl/devbox.go

@@ -822,21 +822,23 @@ func (d *Devbox) computeNixEnv(ctx context.Context, usePrintDevEnvCache bool) (m
 
 	addEnvIfNotPreviouslySetByDevbox(env, pluginEnv)
 
+	envPaths := []string{}
+	if !featureflag.PromptHook.Enabled() {
+		envPaths = append(envPaths, filepath.Join(d.projectDir, plugin.WrapperBinPath))
+	}
+	// Adding profile bin path is a temporary hack. Some packages .e.g. curl
+	// don't export the correct bin in the package, instead they export
+	// as a propagated build input. This can be fixed in 2 ways:
+	// * have NixBins() recursively look for bins in propagated build inputs
+	// * Turn existing planners into flakes (i.e. php, haskell) and use the bins
+	// in the profile.
+	// Landau: I prefer option 2 because it doesn't require us to re-implement
+	// nix recursive bin lookup.
+	envPaths = append(envPaths, nix.ProfileBinPath(d.projectDir), env["PATH"])
+
 	// Prepend virtenv bin path first so user can override it if needed. Virtenv
 	// is where the bin wrappers live
-	env["PATH"] = JoinPathLists(
-		filepath.Join(d.projectDir, plugin.WrapperBinPath),
-		// Adding profile bin path is a temporary hack. Some packages .e.g. curl
-		// don't export the correct bin in the package, instead they export
-		// as a propagated build input. This can be fixed in 2 ways:
-		// * have NixBins() recursively look for bins in propagated build inputs
-		// * Turn existing planners into flakes (i.e. php, haskell) and use the bins
-		// in the profile.
-		// Landau: I prefer option 2 because it doesn't require us to re-implement
-		// nix recursive bin lookup.
-		nix.ProfileBinPath(d.projectDir),
-		env["PATH"],
-	)
+	env["PATH"] = JoinPathLists(envPaths...)
 
 	// Include env variables in devbox.json
 	configEnv := d.configEnvs(env)

internal/impl/generate/devcontainer_util.go

@@ -17,6 +17,7 @@ import (
 	"runtime/trace"
 	"strings"
 
+	"go.jetpack.io/devbox/internal/boxcli/featureflag"
 	"go.jetpack.io/devbox/internal/debug"
 )
 
@@ -159,5 +160,9 @@ func getDevcontainerContent(pkgs []string) *devcontainerObject {
 func EnvrcContent(w io.Writer) error {
 	tmplName := "envrcContent.tmpl"
 	t := template.Must(template.ParseFS(tmplFS, "tmpl/"+tmplName))
-	return t.Execute(w, nil)
+	return t.Execute(w, struct {
+		PromptHookEnabled bool
+	}{
+		PromptHookEnabled: featureflag.PromptHook.Enabled(),
+	})
 }

internal/impl/generate/tmpl/envrcContent.tmpl

@@ -1,5 +1,9 @@
 use_devbox() {
     watch_file devbox.json
+    {{ .PromptHookEnabled }}
+    eval "$(devbox export --init-hook --install)"
+    {{ else }}
     eval "$(devbox shellenv --init-hook --install)"
+    {{ end }}
 }
 use devbox

internal/impl/shell.go

@@ -16,6 +16,8 @@ import (
 
 	"github.com/alessio/shellescape"
 	"github.com/pkg/errors"
+	"go.jetpack.io/devbox/internal/boxcli/featureflag"
+	"go.jetpack.io/devbox/internal/shenv"
 
 	"go.jetpack.io/devbox/internal/debug"
 	"go.jetpack.io/devbox/internal/envir"
@@ -314,21 +316,25 @@ func (s *DevboxShell) writeDevboxShellrc() (path string, err error) {
 	}
 
 	err = tmpl.Execute(shellrcf, struct {
-		ProjectDir       string
-		OriginalInit     string
-		OriginalInitPath string
-		HooksFilePath    string
-		ShellStartTime   string
-		HistoryFile      string
-		ExportEnv        string
+		ProjectDir        string
+		OriginalInit      string
+		OriginalInitPath  string
+		HooksFilePath     string
+		ShellName         string
+		ShellStartTime    string
+		HistoryFile       string
+		ExportEnv         string
+		PromptHookEnabled bool
 	}{
-		ProjectDir:       s.projectDir,
-		OriginalInit:     string(bytes.TrimSpace(userShellrc)),
-		OriginalInitPath: s.userShellrcPath,
-		HooksFilePath:    s.hooksFilePath,
-		ShellStartTime:   s.shellStartTime,
-		HistoryFile:      strings.TrimSpace(s.historyFile),
-		ExportEnv:        exportify(s.env),
+		ProjectDir:        s.projectDir,
+		OriginalInit:      string(bytes.TrimSpace(userShellrc)),
+		OriginalInitPath:  s.userShellrcPath,
+		HooksFilePath:     s.hooksFilePath,
+		ShellName:         string(s.name),
+		ShellStartTime:    s.shellStartTime,
+		HistoryFile:       strings.TrimSpace(s.historyFile),
+		ExportEnv:         exportify(s.env),
+		PromptHookEnabled: featureflag.PromptHook.Enabled(),
 	})
 	if err != nil {
 		return "", fmt.Errorf("execute shellrc template: %v", err)
@@ -411,3 +417,23 @@ func filterPathList(pathList string, keep func(string) bool) string {
 	}
 	return strings.Join(filtered, string(filepath.ListSeparator))
 }
+
+func (d *Devbox) ExportHook(shellName string) (string, error) {
+	if !featureflag.PromptHook.Enabled() {
+		return "", nil
+	}
+
+	// TODO: use a single common "enum" for both shenv and DevboxShell
+	hookTemplate, err := shenv.DetectShell(shellName).Hook()
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	err = template.Must(template.New("hookTemplate").Parse(hookTemplate)).
+		Execute(&buf, struct{ ProjectDir string }{ProjectDir: d.projectDir})
+	if err != nil {
+		return "", errors.WithStack(err)
+	}
+	return buf.String(), nil
+}

internal/impl/shellrc.tmpl

@@ -67,3 +67,9 @@ if ! type refresh >/dev/null 2>&1; then
   alias refresh='eval $(devbox shellenv)'
   export DEVBOX_REFRESH_ALIAS="refresh"
 fi
+
+{{- if .PromptHookEnabled }}
+# Ensure devbox shellenv is evaluated
+# TODO savil: how do I wrap ProjectDir in quotes?
+eval "$(devbox hook {{ .ShellName }} -c {{ .ProjectDir }})"
+{{ end }}

internal/impl/shellrc_fish.tmpl

@@ -70,3 +70,8 @@ if not type refresh >/dev/null 2>&1
     alias refresh='eval (devbox shellenv | string collect)'
     export DEVBOX_REFRESH_ALIAS="refresh"
 end
+
+{{ if .PromptHookEnabled }}
+# Ensure devbox shellenv is evaluated
+devbox hook fish -c "{{ .ProjectDir }}" | source
+{{ end }}

internal/shenv/shell_bash.go

@@ -11,7 +11,7 @@ const bashHook = `
 _devbox_hook() {
   local previous_exit_status=$?;
   trap -- '' SIGINT;
-  eval "$(devbox shellenv --config {{ .ProjectDir }})";
+  eval "$(devbox export --config {{ .ProjectDir }})";
   trap - SIGINT;
   return $previous_exit_status;
 };

internal/shenv/shell_fish.go

@@ -12,7 +12,7 @@ var Fish Shell = fish{}
 
 const fishHook = `
 function __devbox_shellenv_eval --on-event fish_prompt;
-  devbox shellenv --config {{ .ProjectDir }} | source;
+  devbox export --config {{ .ProjectDir }} | source;
 end;
 `
 

internal/shenv/shell_ksh.go

@@ -8,7 +8,7 @@ var Ksh Shell = ksh{}
 // um, this is ChatGPT writing it. I need to verify and test
 const kshHook = `
 _devbox_hook() {
-  eval "$(devbox shellenv --config {{ .ProjectDir }})";
+  eval "$(devbox export --config {{ .ProjectDir }})";
 }
 if [[ "$(typeset -f precmd)" != *"_devbox_hook"* ]]; then
   function precmd {

internal/shenv/shell_posix.go

@@ -12,7 +12,7 @@ const posixHook = `
 _devbox_hook() {
   local previous_exit_status=$?
   trap : INT
-  eval "$(devbox shellenv --config {{ .ProjectDir }})"
+  eval "$(devbox export --config {{ .ProjectDir }})"
   trap - INT
   return $previous_exit_status
 }

internal/shenv/shell_zsh.go

@@ -9,7 +9,7 @@ var Zsh Shell = zsh{}
 const zshHook = `
 _devbox_hook() {
   trap -- '' SIGINT;
-  eval "$(devbox shellenv --config {{ .ProjectDir }})";
+  eval "$(devbox export --config {{ .ProjectDir }})";
   trap - SIGINT;
 }
 typeset -ag precmd_functions;