perf(generate): skip nix check and telemetry for direnv --print-envrc

internal/boxcli/generate.go

@@ -12,6 +12,7 @@ import (
 	"github.com/samber/lo"
 	"github.com/spf13/cobra"
 
+	"go.jetify.com/devbox/internal/boxcli/midcobra"
 	"go.jetify.com/devbox/internal/boxcli/usererr"
 	"go.jetify.com/devbox/internal/devbox"
 	"go.jetify.com/devbox/internal/devbox/devopt"
@@ -48,11 +49,18 @@ func generateCmd() *cobra.Command {
 	flags := &generateCmdFlags{}
 
 	command := &cobra.Command{
-		Use:               "generate",
-		Aliases:           []string{"gen"},
-		Short:             "Generate supporting files for your project",
-		Args:              cobra.MaximumNArgs(0),
-		PersistentPreRunE: ensureNixInstalled,
+		Use:     "generate",
+		Aliases: []string{"gen"},
+		Short:   "Generate supporting files for your project",
+		Args:    cobra.MaximumNArgs(0),
+		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
+			// direnv runs `generate direnv --print-envrc` on every reload. It
+			// only prints a fixed template, so it doesn't need nix.
+			if isPrintEnvrc(cmd) {
+				return nil
+			}
+			return ensureNixInstalled(cmd, args)
+		},
 	}
 	command.AddCommand(genAliasCmd())
 	command.AddCommand(devcontainerCmd())
@@ -294,6 +302,12 @@ func runGenerateCmd(cmd *cobra.Command, flags *generateCmdFlags) error {
 	return nil
 }
 
+// isPrintEnvrc reports whether cmd is `generate direnv --print-envrc`.
+func isPrintEnvrc(cmd *cobra.Command) bool {
+	printEnvrc, err := cmd.Flags().GetBool("print-envrc")
+	return err == nil && printEnvrc
+}
+
 func runGenerateDirenvCmd(cmd *cobra.Command, flags *generateCmdFlags) error {
 	// --print-envrc is used within the .envrc file and therefore doesn't make sense to also
 	// use it with --envrc-dir, which specifies a directory where the .envrc file should be generated.
@@ -305,6 +319,8 @@ func runGenerateDirenvCmd(cmd *cobra.Command, flags *generateCmdFlags) error {
 	}
 
 	if flags.printEnvrcContent {
+		// direnv runs this on every reload, so don't record it.
+		midcobra.SkipTelemetry(cmd)
 		return devbox.PrintEnvrcContent(
 			cmd.OutOrStdout(), devopt.EnvFlags(flags.envFlag), flags.config.path,
 		)

internal/boxcli/generate_test.go

@@ -3,7 +3,13 @@
 
 package boxcli
 
-import "testing"
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"go.jetify.com/devbox/internal/nix"
+)
 
 func TestGenerateSubcommandsAcceptConfigFlags(t *testing.T) {
 	for _, sub := range generateCmd().Commands() {
@@ -14,3 +20,25 @@ func TestGenerateSubcommandsAcceptConfigFlags(t *testing.T) {
 		})
 	}
 }
+
+// TestGenerateDirenvPrintEnvrcSkipsNixCheck ensures that `generate direnv
+// --print-envrc`, which direnv runs on every reload, doesn't check for nix.
+func TestGenerateDirenvPrintEnvrcSkipsNixCheck(t *testing.T) {
+	if nix.Ensured() {
+		t.Skip("an earlier test already ensured nix is installed")
+	}
+
+	root := RootCmd()
+	stdout := &bytes.Buffer{}
+	root.SetOut(stdout)
+	root.SetArgs([]string{"generate", "direnv", "--print-envrc"})
+	if err := root.Execute(); err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(stdout.String(), "devbox shellenv") {
+		t.Errorf("got output %q, want an .envrc that calls devbox shellenv", stdout)
+	}
+	if nix.Ensured() {
+		t.Error("generate direnv --print-envrc checked that nix is installed")
+	}
+}

internal/boxcli/midcobra/midcobra_test.go

@@ -42,3 +42,14 @@ func TestExecuteParsesPersistentFlagsAfterUnknownFlags(t *testing.T) {
 		t.Error("Execute() with an unknown root flag = 0, want non-zero")
 	}
 }
+
+func TestSkipTelemetry(t *testing.T) {
+	cmd := &cobra.Command{Use: "test"}
+	if telemetrySkipped(cmd) {
+		t.Error("telemetry skipped before calling SkipTelemetry")
+	}
+	SkipTelemetry(cmd)
+	if !telemetrySkipped(cmd) {
+		t.Error("telemetry not skipped after calling SkipTelemetry")
+	}
+}

internal/boxcli/midcobra/telemetry.go

@@ -32,6 +32,23 @@ type telemetryMiddleware struct{}
 // telemetryMiddleware implements interface Middleware (compile-time check)
 var _ Middleware = (*telemetryMiddleware)(nil)
 
+// skipTelemetryAnnotation is set on a command by SkipTelemetry.
+const skipTelemetryAnnotation = "devbox.skip-telemetry"
+
+// SkipTelemetry stops the telemetry middleware from recording the current run
+// of cmd. Use it for commands that run so often in the background (e.g. on
+// every direnv reload) that recording them isn't useful.
+func SkipTelemetry(cmd *cobra.Command) {
+	if cmd.Annotations == nil {
+		cmd.Annotations = map[string]string{}
+	}
+	cmd.Annotations[skipTelemetryAnnotation] = "true"
+}
+
+func telemetrySkipped(cmd *cobra.Command) bool {
+	return cmd.Annotations[skipTelemetryAnnotation] != ""
+}
+
 func (m *telemetryMiddleware) preRun(cmd *cobra.Command, args []string) {
 	telemetry.Start()
 }
@@ -51,6 +68,9 @@ func (m *telemetryMiddleware) postRun(cmd *cobra.Command, args []string, runErr
 		// Ignore invalid commands/flags.
 		return
 	}
+	if telemetrySkipped(subcmd) {
+		return
+	}
 	meta.Command = subcmd.CommandPath()
 	meta.CommandFlags = flags
 

specs/perf-improvements.md

@@ -105,7 +105,7 @@ every successful command. Fix: record the last upload time in the state dir and
 only spawn the uploader when it was more than N minutes ago, or when the
 buffered event count exceeds a threshold.
 
-### 5. Make `generate direnv --print-envrc` cheap
+### 5. Make `generate direnv --print-envrc` cheap (done in #3022)
 
 **Win:** every direnv reload.
 **Effort:** ~15–30 LOC.