[sdk/go] Respect default parent in go aliases. (#8288)

* Respect default parent in go aliases.

* Update changelog

* Handle empty parrents correctly

* Allow specifying no parent

* clarify variable name

* Improve `Unparent` ergonomics

* Take t0yv0's suggestion

* Adopt @t0yv0's tests and doc comments.

* Make NoParent,Parent,ParentURN mutually exclusive

CHANGELOG_PENDING.md

@@ -1,5 +1,15 @@
 ### Improvements
 
+- [cli] Reformat error message string in `sdk/go/common/diag/errors.go`
+  [#8284](https://github.com/pulumi/pulumi/pull/8284)
+
+### Bug Fixes
+
+- [sdk/go] - Respect implicit parents in alias resolution
+  [#8288](https://github.com/pulumi/pulumi/pull/8288)
+
+- [sdk/dotnet] - Fix a race condition when detecting exceptions in stack creation
+  [#8294](https://github.com/pulumi/pulumi/pull/8294)
  - Clarify error message string in `sdk/go/common/diag/errors.go`
    [#8284](https://github.com/pulumi/pulumi/pull/8284)
 
@@ -11,8 +21,6 @@
 
   [#8275](https://github.com/pulumi/pulumi/pull/8275)
 
-### Bug Fixes
-
 - [codegen/go] - Interaction between the `plain` and `default` tags of a type. 
   [#8254](https://github.com/pulumi/pulumi/pull/8254)
 

sdk/go/pulumi/alias.go

@@ -1,4 +1,4 @@
-// Copyright 2016-2020, Pulumi Corporation.
+// Copyright 2016-2021, Pulumi Corporation.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,6 +16,7 @@ package pulumi
 
 import (
 	"errors"
+	"fmt"
 	"strings"
 )
 
@@ -29,16 +30,35 @@ type Alias struct {
 	Name StringInput
 	// The previous type of the resource.  If not provided, the current type of the resource is used.
 	Type StringInput
-	// The previous parent of the resource.  If not provided, the current parent of the resource is used.
+	// The previous parent of the resource. If not provided, the current parent of the resource is used by default.
+	// This option is mutually exclusive to `ParentURN` and `NoParent`.
+	// Use `Alias { NoParent: pulumi.Bool(true) }` to avoid defaulting to the current parent.
 	Parent Resource
-	// The previous parent of the resource in URN format, mutually exclusive to 'Parent'
+	// The previous parent of the resource in URN format, mutually exclusive to `Parent` and `ParentURN`.
+	// To specify no original parent, use `Alias { NoParent: pulumi.Bool(true) }`.
 	ParentURN URNInput
+	// When true, indicates that the resource previously had no parent.
+	// This option is mutually exclusive to `Parent` and `ParentURN`.
+	NoParent BoolInput
 	// The name of the previous stack of the resource.  If not provided, defaults to `context.GetStack()
 	Stack StringInput
 	// The previous project of the resource. If not provided, defaults to `context.GetProject()`.
 	Project StringInput
 }
 
+// More then one bool is set to true.
+func multipleTrue(booleans ...bool) bool {
+	var found bool
+	for _, b := range booleans {
+		if b && found {
+			return true
+		} else if b {
+			found = true
+		}
+	}
+	return false
+}
+
 func (a Alias) collapseToURN(defaultName, defaultType string, defaultParent Resource,
 	defaultProject, defaultStack string) (URNOutput, error) {
 
@@ -55,16 +75,27 @@ func (a Alias) collapseToURN(defaultName, defaultType string, defaultParent Reso
 		t = String(defaultType)
 	}
 
-	var parent StringInput
-	if a.Parent != nil && a.ParentURN != nil {
-		return URNOutput{}, errors.New("alias can specify either Parent or ParentURN but not both")
+	var parent StringInput = String("")
+	if defaultParent != nil {
+		parent = defaultParent.URN().ToStringOutput()
+	}
+	if multipleTrue(a.Parent != nil, a.ParentURN != nil, a.NoParent != nil) {
+		return URNOutput{}, errors.New("alias can specify Parent, ParentURN or NoParent but not more then one")
 	}
 	if a.Parent != nil {
-		parent = a.Parent.URN()
+		parent = a.Parent.URN().ToStringOutput()
 	}
 	if a.ParentURN != nil {
 		parent = a.ParentURN.ToURNOutput()
 	}
+	if a.NoParent != nil {
+		parent = All(a.NoParent.ToBoolOutput(), parent).ApplyT(func(a []interface{}) string {
+			if a[0].(bool) {
+				return ""
+			}
+			return a[1].(string)
+		}).(StringOutput)
+	}
 
 	project := a.Project
 	if project == nil {
@@ -80,20 +111,27 @@ func (a Alias) collapseToURN(defaultName, defaultType string, defaultParent Reso
 
 // CreateURN computes a URN from the combination of a resource name, resource type, and optional parent,
 func CreateURN(name, t, parent, project, stack StringInput) URNOutput {
-	var parentPrefix StringInput
-	if parent != nil {
-		parentPrefix = parent.ToStringOutput().ApplyT(func(p string) string {
-			return p[0:strings.LastIndex(p, "::")] + "$"
-		}).(StringOutput)
-	} else {
-		parentPrefix = All(stack, project).ApplyT(func(a []interface{}) string {
-			return "urn:pulumi:" + a[0].(string) + "::" + a[1].(string) + "::"
-		}).(StringOutput)
-
+	if parent == nil {
+		parent = String("")
 	}
-
-	return All(parentPrefix, t, name).ApplyT(func(a []interface{}) URN {
-		return URN(a[0].(string) + a[1].(string) + "::" + a[2].(string))
+	createURN := func(parent, stack, project, t, name string) URN {
+		var parentPrefix string
+		if parent == "" {
+			parentPrefix = "urn:pulumi:" + stack + "::" + project + "::"
+		} else {
+			ix := strings.LastIndex(parent, "::")
+			if ix == -1 {
+				panic(fmt.Sprintf("Expected 'parent' string '%s' to contain '::'", parent))
+			}
+			parentPrefix = parent[0:ix] + "$"
+		}
+		return URN(parentPrefix + t + "::" + name)
+	}
+	// The explicit call to `ToStringOutput` is necessary because `URNOutput`
+	// conforms to `StringInput` so `parent.(string)` can fail without the
+	// explicit conversion.
+	return All(parent.ToStringOutput(), stack, project, t, name).ApplyT(func(a []interface{}) URN {
+		return createURN(a[0].(string), a[1].(string), a[2].(string), a[3].(string), a[4].(string))
 	}).(URNOutput)
 }
 
@@ -108,5 +146,5 @@ func inheritedChildAlias(childName, parentName, childType, project, stack string
 			return string(parentPrefix) + childName[len(parentName):]
 		}).(StringOutput)
 	}
-	return CreateURN(aliasName, String(childType), parentURN, String(project), String(stack))
+	return CreateURN(aliasName, String(childType), parentURN.ToStringOutput(), String(project), String(stack))
 }

sdk/go/pulumi/alias_test.go

@@ -0,0 +1,84 @@
+// Copyright 2016-2021, Pulumi Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package pulumi
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var aliasTestCases = []struct {
+	name        string
+	alias       func(t *testing.T) Alias
+	expectedURN string
+}{
+	{
+		"plain",
+		func(*testing.T) Alias {
+			return Alias{
+				Type: String("kubernetes:storage.k8s.io/v1beta1:CSIDriver"),
+			}
+		},
+		"AnUrn$kubernetes:storage.k8s.io/v1beta1:CSIDriver::defName",
+	},
+	{
+		"noParent",
+		func(*testing.T) Alias {
+			return Alias{
+				Type:     String("kubernetes:storage.k8s.io/v1beta1:CSIDriver"),
+				NoParent: Bool(true),
+			}
+		}, "urn:pulumi:defStack::defProject::kubernetes:storage.k8s.io/v1beta1:CSIDriver::defName",
+	},
+	{
+		"parent",
+		func(t *testing.T) Alias {
+			return Alias{
+				Type:   String("kubernetes:storage.k8s.io/v1beta1:CSIDriver"),
+				Parent: newResource(t, URN("AParent::AParent"), ID("theParent")),
+			}
+		}, "AParent$kubernetes:storage.k8s.io/v1beta1:CSIDriver::defName",
+	},
+	{
+		"parentURN",
+		func(*testing.T) Alias {
+			return Alias{
+				Type:      String("kubernetes:storage.k8s.io/v1beta1:CSIDriver"),
+				ParentURN: URN("AParent::AParent"),
+			}
+		}, "AParent$kubernetes:storage.k8s.io/v1beta1:CSIDriver::defName",
+	},
+}
+
+func TestAliasResolution(t *testing.T) {
+	for _, tt := range aliasTestCases {
+		t.Run(tt.name, func(t *testing.T) {
+			parent := newResource(t, URN("AnUrn::ASegment"), ID("hello"))
+			out, err := tt.alias(t).collapseToURN("defName", "defType", parent, "defProject", "defStack")
+			assert.NoError(t, err)
+			urn, _, _, err := out.awaitURN(context.Background())
+			assert.NoError(t, err)
+			assert.Equal(t, URN(tt.expectedURN), urn)
+		})
+	}
+}
+
+func newResource(t *testing.T, urn URN, id ID) Resource {
+	ctx, err := NewContext(context.Background(), RunInfo{})
+	assert.NoError(t, err)
+	return newSimpleCustomResource(ctx, urn, id)
+}

sdk/go/pulumi/context.go

@@ -551,6 +551,7 @@ func (ctx *Context) ReadResource(
 	}
 
 	options := merge(opts...)
+	aliasParent := options.Parent
 	if options.Parent == nil {
 		options.Parent = ctx.stack
 	}
@@ -563,7 +564,7 @@ func (ctx *Context) ReadResource(
 	}
 
 	// Collapse aliases to URNs.
-	aliasURNs, err := ctx.collapseAliases(options.Aliases, t, name, options.Parent)
+	aliasURNs, err := ctx.collapseAliases(options.Aliases, t, name, aliasParent)
 	if err != nil {
 		return err
 	}
@@ -736,6 +737,7 @@ func (ctx *Context) registerResource(
 	}
 
 	options := merge(opts...)
+	parent := options.Parent
 	if options.Parent == nil {
 		options.Parent = ctx.stack
 	}
@@ -748,7 +750,7 @@ func (ctx *Context) registerResource(
 	}
 
 	// Collapse aliases to URNs.
-	aliasURNs, err := ctx.collapseAliases(options.Aliases, t, name, options.Parent)
+	aliasURNs, err := ctx.collapseAliases(options.Aliases, t, name, parent)
 	if err != nil {
 		return err
 	}

tests/integration/aliases/go/adopt_into_component/step2/main.go

@@ -80,9 +80,13 @@ func NewFooComponent3(ctx *pulumi.Context,
 		return nil, err
 	}
 
-	alias := &pulumi.Alias{
-		Parent: childAliasParent,
+	var alias = &pulumi.Alias{}
+	if childAliasParent != nil {
+		alias.Parent = childAliasParent
+	} else {
+		alias.NoParent = pulumi.Bool(true)
 	}
+
 	aliasOpt := pulumi.Aliases([]pulumi.Alias{*alias})
 	parentOpt := pulumi.Parent(fooComp)
 	_, err = NewFooComponent2(ctx, name+"-child", aliasOpt, parentOpt)
@@ -114,7 +118,7 @@ func main() {
 			return err
 		}
 		alias := &pulumi.Alias{
-			Parent: nil,
+			NoParent: pulumi.Bool(true),
 		}
 		aliasOpt := pulumi.Aliases([]pulumi.Alias{*alias})
 		parentOpt := pulumi.Parent(comp2)