Add special diff for nested blocks

When a value in a nested block is marked as sensitive,
it will result in the behavior of every member of
that block being sensitive. As such, show a
specialized diff that reduces noise of (sensitive)
for many attributes that we won't show. Also update
the warning to differentiate between showing a warning
for an attribute or warning for blocks.

command/format/diff.go

@@ -338,7 +338,7 @@ func (p *blockBodyDiffPrinter) writeAttrDiff(name string, attrS *configschema.At
 
 	p.buf.WriteString("\n")
 
-	p.writeSensitivityWarning(old, new, indent, action)
+	p.writeSensitivityWarning(old, new, indent, action, false)
 
 	p.buf.WriteString(strings.Repeat(" ", indent))
 	p.writeActionSymbol(action)
@@ -377,6 +377,49 @@ func (p *blockBodyDiffPrinter) writeNestedBlockDiffs(name string, blockS *config
 		return skippedBlocks
 	}
 
+	// If either the old or the new value is marked,
+	// Display a special diff because it is irrelevant
+	// to list all obfuscated attributes as (sensitive)
+	if old.IsMarked() || new.IsMarked() {
+		unmarkedOld, _ := old.Unmark()
+		unmarkedNew, _ := new.Unmark()
+		eqV := unmarkedNew.Equals(unmarkedOld)
+		var action plans.Action
+		switch {
+		case old.IsNull():
+			action = plans.Create
+		case new.IsNull():
+			action = plans.Delete
+		case !new.IsWhollyKnown() || !old.IsWhollyKnown():
+			// "old" should actually always be known due to our contract
+			// that old values must never be unknown, but we'll allow it
+			// anyway to be robust.
+			action = plans.Update
+		case !eqV.IsKnown() || !eqV.True():
+			action = plans.Update
+		}
+
+		if blankBefore {
+			p.buf.WriteRune('\n')
+		}
+
+		// New line before warning printing
+		p.buf.WriteRune('\n')
+		p.writeSensitivityWarning(old, new, indent, action, true)
+		p.buf.WriteString(strings.Repeat(" ", indent))
+		p.writeActionSymbol(action)
+		fmt.Fprintf(p.buf, "%s {", name)
+		p.buf.WriteRune('\n')
+		p.buf.WriteString(strings.Repeat(" ", indent+4))
+		p.buf.WriteString("# At least one attribute in this block is (or was) sensitive,\n")
+		p.buf.WriteString(strings.Repeat(" ", indent+4))
+		p.buf.WriteString("# so its contents will not be displayed.")
+		p.buf.WriteRune('\n')
+		p.buf.WriteString(strings.Repeat(" ", indent+2))
+		p.buf.WriteString("}")
+		return 0
+	}
+
 	// Where old/new are collections representing a nesting mode other than
 	// NestingSingle, we assume the collection value can never be unknown
 	// since we always produce the container for the nested objects, even if
@@ -1129,7 +1172,7 @@ func (p *blockBodyDiffPrinter) writeValueDiff(old, new cty.Value, indent int, pa
 
 				oldV := old.Index(kV)
 				newV := new.Index(kV)
-				p.writeSensitivityWarning(oldV, newV, indent+2, action)
+				p.writeSensitivityWarning(oldV, newV, indent+2, action, false)
 
 				p.buf.WriteString(strings.Repeat(" ", indent+2))
 				p.writeActionSymbol(action)
@@ -1307,15 +1350,21 @@ func (p *blockBodyDiffPrinter) writeActionSymbol(action plans.Action) {
 	}
 }
 
-func (p *blockBodyDiffPrinter) writeSensitivityWarning(old, new cty.Value, indent int, action plans.Action) {
+func (p *blockBodyDiffPrinter) writeSensitivityWarning(old, new cty.Value, indent int, action plans.Action, isBlock bool) {
 	// Dont' show this warning for create or delete
 	if action == plans.Create || action == plans.Delete {
 		return
 	}
 
+	// Customize the warning based on if it is an attribute or block
+	diffType := "attribute value"
+	if isBlock {
+		diffType = "block"
+	}
+
 	if new.IsMarked() && !old.IsMarked() {
 		p.buf.WriteString(strings.Repeat(" ", indent))
-		p.buf.WriteString(p.color.Color("# [yellow]Warning:[reset] this attribute value will be marked as sensitive and will\n"))
+		p.buf.WriteString(p.color.Color(fmt.Sprintf("# [yellow]Warning:[reset] this %s will be marked as sensitive and will\n", diffType)))
 		p.buf.WriteString(strings.Repeat(" ", indent))
 		p.buf.WriteString(p.color.Color("# not display in UI output after applying this change\n"))
 	}
@@ -1323,7 +1372,7 @@ func (p *blockBodyDiffPrinter) writeSensitivityWarning(old, new cty.Value, inden
 	// Note if changing this attribute will change its sensitivity
 	if old.IsMarked() && !new.IsMarked() {
 		p.buf.WriteString(strings.Repeat(" ", indent))
-		p.buf.WriteString(p.color.Color("# [yellow]Warning:[reset] this attribute value will no longer be marked as sensitive\n"))
+		p.buf.WriteString(p.color.Color(fmt.Sprintf("# [yellow]Warning:[reset] this %s will no longer be marked as sensitive\n", diffType)))
 		p.buf.WriteString(strings.Repeat(" ", indent))
 		p.buf.WriteString(p.color.Color("# after applying this change\n"))
 	}
@@ -1373,15 +1422,10 @@ func ctyCollectionValues(val cty.Value) []cty.Value {
 		return nil
 	}
 
-	// Sets with marks mark the whole set as marked,
-	// so when we unmark it, apply those marks to all members
-	// of the set
-	val, marks := val.Unmark()
-
 	ret := make([]cty.Value, 0, val.LengthInt())
 	for it := val.ElementIterator(); it.Next(); {
 		_, value := it.Element()
-		ret = append(ret, value.WithMarks(marks))
+		ret = append(ret, value)
 	}
 	return ret
 }

command/format/diff_test.go

@@ -3644,7 +3644,7 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					cty.StringVal("friends"),
 					cty.StringVal("!"),
 				}),
-				"nested_block": cty.ListVal([]cty.Value{
+				"nested_block_list": cty.ListVal([]cty.Value{
 					cty.ObjectVal(map[string]cty.Value{
 						"an_attr": cty.StringVal("secretval"),
 						"another": cty.StringVal("not secret"),
@@ -3670,7 +3670,7 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 				},
 				{
 					// Nested blocks/sets will mark the whole set/block as sensitive
-					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block"}},
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_list"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
 			},
@@ -3685,7 +3685,7 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"list_field": {Type: cty.List(cty.String), Optional: true},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{
-					"nested_block": {
+					"nested_block_list": {
 						Block: configschema.Block{
 							Attributes: map[string]*configschema.Attribute{
 								"an_attr": {Type: cty.String, Optional: true},
@@ -3711,9 +3711,9 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
         }
       + map_whole  = (sensitive)
 
-      + nested_block {
+      + nested_block_list {
-          + an_attr = (sensitive)
+          # At least one attribute in this block is (or was) sensitive,
-          + another = (sensitive)
+          # so its contents will not be displayed.
         }
     }
 `,
@@ -3742,7 +3742,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 				"nested_block": cty.ListVal([]cty.Value{
 					cty.ObjectVal(map[string]cty.Value{
 						"an_attr": cty.StringVal("secretval"),
-						"another": cty.StringVal("not secret"),
+					}),
+				}),
+				"nested_block_set": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"an_attr": cty.StringVal("secretval"),
 					}),
 				}),
 			}),
@@ -3767,7 +3771,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 				"nested_block": cty.ListVal([]cty.Value{
 					cty.ObjectVal(map[string]cty.Value{
 						"an_attr": cty.StringVal("changed"),
-						"another": cty.StringVal("not secret"),
+					}),
+				}),
+				"nested_block_set": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"an_attr": cty.StringVal("changed"),
 					}),
 				}),
 			}),
@@ -3800,6 +3808,10 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
+				{
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_set"}},
+					Marks: cty.NewValueMarks("sensitive"),
+				},
 			},
 			RequiredReplace: cty.NewPathSet(),
 			Tainted:         false,
@@ -3814,14 +3826,13 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"map_whole":   {Type: cty.Map(cty.String), Optional: true},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{
-					"nested_block": {
+					"nested_block_set": {
 						Block: configschema.Block{
 							Attributes: map[string]*configschema.Attribute{
 								"an_attr": {Type: cty.String, Optional: true},
-								"another": {Type: cty.String, Optional: true},
 							},
 						},
-						Nesting: configschema.NestingList,
+						Nesting: configschema.NestingSet,
 					},
 				},
 			},
@@ -3853,11 +3864,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
       # after applying this change
       ~ special     = (sensitive)
 
-      ~ nested_block {
+      # Warning: this block will no longer be marked as sensitive
-          # Warning: this attribute value will no longer be marked as sensitive
+      # after applying this change
-          # after applying this change
+      ~ nested_block_set {
-          ~ an_attr = (sensitive)
+          # At least one attribute in this block is (or was) sensitive,
-            # (1 unchanged attribute hidden)
+          # so its contents will not be displayed.
         }
     }
 `,
@@ -3879,6 +3890,9 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"breakfast": cty.StringVal("pizza"),
 					"dinner":    cty.StringVal("pizza"),
 				}),
+				"nested_block_single": cty.ObjectVal(map[string]cty.Value{
+					"an_attr": cty.StringVal("original"),
+				}),
 			}),
 			After: cty.ObjectVal(map[string]cty.Value{
 				"id": cty.StringVal("i-02ae66f368e8518a9"),
@@ -3894,6 +3908,9 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"breakfast": cty.StringVal("cereal"),
 					"dinner":    cty.StringVal("pizza"),
 				}),
+				"nested_block_single": cty.ObjectVal(map[string]cty.Value{
+					"an_attr": cty.StringVal("changed"),
+				}),
 			}),
 			AfterValMarks: []cty.PathValueMarks{
 				{
@@ -3912,6 +3929,13 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					Path:  cty.Path{cty.GetAttrStep{Name: "map_whole"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
+				{
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_single"}},
+					Marks: cty.NewValueMarks("sensitive"),
+				},
+				{
+					Marks: cty.NewValueMarks("sensitive"),
+				},
 			},
 			RequiredReplace: cty.NewPathSet(),
 			Tainted:         false,
@@ -3922,6 +3946,16 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"map_key":    {Type: cty.Map(cty.Number), Optional: true},
 					"map_whole":  {Type: cty.Map(cty.String), Optional: true},
 				},
+				BlockTypes: map[string]*configschema.NestedBlock{
+					"nested_block_single": {
+						Block: configschema.Block{
+							Attributes: map[string]*configschema.Attribute{
+								"an_attr": {Type: cty.String, Optional: true},
+							},
+						},
+						Nesting: configschema.NestingSingle,
+					},
+				},
 			},
 			ExpectedOutput: `  # test_instance.example will be updated in-place
   ~ resource "test_instance" "example" {
@@ -3940,6 +3974,13 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
       # Warning: this attribute value will be marked as sensitive and will
       # not display in UI output after applying this change
       ~ map_whole  = (sensitive)
+
+      # Warning: this block will be marked as sensitive and will
+      # not display in UI output after applying this change
+      ~ nested_block_single {
+          # At least one attribute in this block is (or was) sensitive,
+          # so its contents will not be displayed.
+        }
     }
 `,
 		},
@@ -3961,6 +4002,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"breakfast": cty.StringVal("pizza"),
 					"dinner":    cty.StringVal("pizza"),
 				}),
+				"nested_block_map": cty.MapVal(map[string]cty.Value{
+					"foo": cty.ObjectVal(map[string]cty.Value{
+						"an_attr": cty.StringVal("original"),
+					}),
+				}),
 			}),
 			After: cty.ObjectVal(map[string]cty.Value{
 				"id":  cty.StringVal("i-02ae66f368e8518a9"),
@@ -3977,6 +4023,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"breakfast": cty.StringVal("cereal"),
 					"dinner":    cty.StringVal("pizza"),
 				}),
+				"nested_block_map": cty.MapVal(map[string]cty.Value{
+					"foo": cty.ObjectVal(map[string]cty.Value{
+						"an_attr": cty.StringVal("changed"),
+					}),
+				}),
 			}),
 			BeforeValMarks: []cty.PathValueMarks{
 				{
@@ -3995,6 +4046,13 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					Path:  cty.Path{cty.GetAttrStep{Name: "map_whole"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
+				{
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_map"}},
+					Marks: cty.NewValueMarks("sensitive"),
+				},
+				{
+					Marks: cty.NewValueMarks("sensitive"),
+				},
 			},
 			AfterValMarks: []cty.PathValueMarks{
 				{
@@ -4013,6 +4071,10 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					Path:  cty.Path{cty.GetAttrStep{Name: "map_whole"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
+				{
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_map"}},
+					Marks: cty.NewValueMarks("sensitive"),
+				},
 			},
 			RequiredReplace: cty.NewPathSet(),
 			Tainted:         false,
@@ -4024,6 +4086,16 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"map_key":    {Type: cty.Map(cty.Number), Optional: true},
 					"map_whole":  {Type: cty.Map(cty.String), Optional: true},
 				},
+				BlockTypes: map[string]*configschema.NestedBlock{
+					"nested_block_map": {
+						Block: configschema.Block{
+							Attributes: map[string]*configschema.Attribute{
+								"an_attr": {Type: cty.String, Optional: true},
+							},
+						},
+						Nesting: configschema.NestingMap,
+					},
+				},
 			},
 			ExpectedOutput: `  # test_instance.example will be updated in-place
   ~ resource "test_instance" "example" {
@@ -4039,6 +4111,11 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
             # (1 unchanged element hidden)
         }
       ~ map_whole  = (sensitive)
+
+      ~ nested_block_map {
+          # At least one attribute in this block is (or was) sensitive,
+          # so its contents will not be displayed.
+        }
     }
 `,
 		},
@@ -4066,6 +4143,12 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 						"another": cty.StringVal("not secret"),
 					}),
 				}),
+				"nested_block_set": cty.ListVal([]cty.Value{
+					cty.ObjectVal(map[string]cty.Value{
+						"an_attr": cty.StringVal("secret"),
+						"another": cty.StringVal("not secret"),
+					}),
+				}),
 			}),
 			After: cty.NullVal(cty.EmptyObject),
 			BeforeValMarks: []cty.PathValueMarks{
@@ -4089,6 +4172,10 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block"}},
 					Marks: cty.NewValueMarks("sensitive"),
 				},
+				{
+					Path:  cty.Path{cty.GetAttrStep{Name: "nested_block_set"}},
+					Marks: cty.NewValueMarks("sensitive"),
+				},
 			},
 			RequiredReplace: cty.NewPathSet(),
 			Tainted:         false,
@@ -4101,14 +4188,14 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
 					"map_whole":  {Type: cty.Map(cty.String), Optional: true},
 				},
 				BlockTypes: map[string]*configschema.NestedBlock{
-					"nested_block": {
+					"nested_block_set": {
 						Block: configschema.Block{
 							Attributes: map[string]*configschema.Attribute{
 								"an_attr": {Type: cty.String, Optional: true},
 								"another": {Type: cty.String, Optional: true},
 							},
 						},
-						Nesting: configschema.NestingList,
+						Nesting: configschema.NestingSet,
 					},
 				},
 			},
@@ -4126,9 +4213,9 @@ func TestResourceChange_sensitiveVariable(t *testing.T) {
         } -> null
       - map_whole  = (sensitive) -> null
 
-      - nested_block {
+      - nested_block_set {
-          - an_attr = (sensitive) -> null
+          # At least one attribute in this block is (or was) sensitive,
-          - another = (sensitive) -> null
+          # so its contents will not be displayed.
         }
     }
 `,