Merge #12303

12303: sdk/go: Fix panic from uninitialized parent resources r=abhinav a=abhinav

# Description

The Go SDK panics if RegisterResource is called with a parent resource
that is uninitialized
(hasn't had its RegisterResource or RegisterComponentResource call yet).

The panic is during alias collapsing:
the system fails to read the unintialized parent resource's URN
from a zero-valued URNOutput.

Guard against this panic by verifying that the value passed to `Parent`
has been initialized.
We do this by checking the name of the resource--names are not allowed
to be empty when a resource is registered.

Resolves #12138

## Checklist

- [x] I have added tests that prove my fix is effective or that my feature works
- [x] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change


Co-authored-by: Abhinav Gupta <[email protected]>

changelog/pending/20230228--sdk-go--fix-panic-from-attempting-to-create-a-resource-with-an-uninitialized-parent-resource.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: sdk/go
+  description: Fix panic from attempting to create a resource with an uninitialized parent resource.

sdk/go/pulumi/context.go

@@ -803,6 +803,26 @@ func (ctx *Context) registerResource(
 	}
 
 	options := merge(opts...)
+
+	if parent := options.Parent; parent != nil && parent.URN().getState() == nil {
+		// Guard against uninitialized parent resources to prevent
+		// panics from invalid state further down the line.
+		// Uninitialized parent resources won't have a URN.
+
+		resourceType := "resource"
+		registerMethod := "RegisterResource"
+		if _, parentIsCustom := parent.(CustomResource); !parentIsCustom {
+			resourceType = "component resource"
+			registerMethod = "RegisterComponentResource"
+		}
+		err := ctx.Log.Warn(fmt.Sprintf(
+			"Ignoring %v %T (parent of %v :: %v) because it was not registered with %v",
+			resourceType, parent, name, t, registerMethod), nil /* args */)
+		contract.IgnoreError(err)
+
+		options.Parent = nil
+	}
+
 	parent := options.Parent
 	if options.Parent == nil {
 		options.Parent = ctx.stack

sdk/go/pulumi/resource_test.go

@@ -15,8 +15,10 @@
 package pulumi
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"log"
 	"reflect"
 	"sync"
 	"testing"
@@ -552,6 +554,107 @@ func TestNewResourceInput(t *testing.T) {
 	assert.Equal(t, "abracadabra", unpackedRes.foo)
 }
 
+// Verifies that a Parent resource that has not been initialized will panic,
+// and will instead report a meaningful error message.
+func TestUninitializedParentResource(t *testing.T) {
+	t.Parallel()
+
+	type myComponent struct {
+		ResourceState
+	}
+
+	type myCustomResource struct {
+		CustomResourceState
+	}
+
+	tests := []struct {
+		desc   string
+		parent Resource
+
+		// additional options to pass to RegisterResource
+		// besides the Parent.
+		// The original report of the panic was with an Alias option.
+		opts []ResourceOption
+
+		// Message that should be part of the error message.
+		wantErr string
+	}{
+		{
+			desc:   "component resource",
+			parent: &myComponent{},
+			wantErr: "WARNING: Ignoring component resource *pulumi.myComponent " +
+				"(parent of my-resource :: test:index:MyResource) " +
+				"because it was not registered with RegisterComponentResource",
+		},
+		{
+			desc:   "component resource/alias",
+			parent: &myComponent{},
+			opts: []ResourceOption{
+				Aliases([]Alias{
+					{Name: String("alias1")},
+				}),
+			},
+			wantErr: "WARNING: Ignoring component resource *pulumi.myComponent " +
+				"(parent of my-resource :: test:index:MyResource) " +
+				"because it was not registered with RegisterComponentResource",
+		},
+		{
+			desc:   "custom resource",
+			parent: &myCustomResource{},
+			wantErr: "WARNING: Ignoring resource *pulumi.myCustomResource " +
+				"(parent of my-resource :: test:index:MyResource) " +
+				"because it was not registered with RegisterResource",
+		},
+		{
+			desc:   "custom resource/alias",
+			parent: &myCustomResource{},
+			opts: []ResourceOption{
+				Aliases([]Alias{
+					{Name: String("alias1")},
+				}),
+			},
+			wantErr: "WARNING: Ignoring resource *pulumi.myCustomResource " +
+				"(parent of my-resource :: test:index:MyResource) " +
+				"because it was not registered with RegisterResource",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.desc, func(t *testing.T) {
+			t.Parallel()
+
+			require.NotEmpty(t, tt.wantErr,
+				"test case must specify an error message")
+
+			err := RunErr(func(ctx *Context) error {
+				// This is a hack.
+				// We're accesing context mock internals
+				// because the mock API does not expose a way
+				// to set the logger.
+				//
+				// If this ever becomes a problem,
+				// add a way to supply a logger to the mock
+				// and use that here.
+				var buff bytes.Buffer
+				ctx.engine.(*mockEngine).logger = log.New(&buff, "", 0)
+
+				opts := []ResourceOption{Parent(tt.parent)}
+				opts = append(opts, tt.opts...)
+
+				var res testRes
+				require.NoError(t, ctx.RegisterResource(
+					"test:index:MyResource",
+					"my-resource",
+					nil /* props */, &res, opts...))
+				assert.Contains(t, buff.String(), tt.wantErr)
+				return nil
+			}, WithMocks("project", "stack", &testMonitor{}))
+			assert.NoError(t, err)
+		})
+	}
+}
+
 func TestDependsOnInputs(t *testing.T) {
 	t.Parallel()