From 22fb218b28c0136e1b3360ae6615f578e3c28c26 Mon Sep 17 00:00:00 2001
From: Andrea Luzzardi <aluzzardi@gmail.com>
Date: Thu, 14 Jan 2021 17:52:39 -0800
Subject: [PATCH] component: do not fail if `#dagger` marker has no compute

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>
---
 dagger/component.go | 11 ++++++++++-
 dagger/script.go    |  2 +-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/dagger/component.go b/dagger/component.go
index 6acdeb21..874d1512 100644
--- a/dagger/component.go
+++ b/dagger/component.go
@@ -2,6 +2,7 @@ package dagger
 
 import (
 	"context"
+	"os"
 )
 
 type Component struct {
@@ -37,7 +38,11 @@ func (c *Component) Validate() error {
 
 // Return this component's compute script.
 func (c *Component) ComputeScript() (*Script, error) {
-	return c.Value().Get("#dagger.compute").Script()
+	v := c.Value().Get("#dagger.compute")
+	if !v.Exists() {
+		return nil, os.ErrNotExist
+	}
+	return v.Script()
 }
 
 // Compute the configuration for this component.
@@ -62,6 +67,10 @@ func (c *Component) Compute(ctx context.Context, s Solver, out Fillable) (FS, er
 func (c *Component) Execute(ctx context.Context, fs FS, out Fillable) (FS, error) {
 	script, err := c.ComputeScript()
 	if err != nil {
+		// If the component has no script, then do not fail.
+		if os.IsNotExist(err) {
+			return fs, nil
+		}
 		return fs, err
 	}
 	return script.Execute(ctx, fs, out)
diff --git a/dagger/script.go b/dagger/script.go
index b15752f5..03b6ce11 100644
--- a/dagger/script.go
+++ b/dagger/script.go
@@ -10,7 +10,7 @@ type Script struct {
 	v *Value
 }
 
-func (s Script) Validate() error {
+func (s *Script) Validate() error {
 	// FIXME this crashes when a script is incomplete or empty
 	return s.Value().Validate("#Script")
 }