From f1a292652dd437a5bf1561324f77e0b832d973ea Mon Sep 17 00:00:00 2001
From: Alisdair McDiarmid <alisdair@users.noreply.github.com>
Date: Tue, 16 Feb 2021 15:32:36 -0500
Subject: [PATCH] terraform: Fix missing deposed key for PreApply

The PreApply hook was always being called with a nil generation
argument, instead of the deposed key of the resource (if present). This
commit passes the deposed key from the change to the PreApply hook, and
adds a context test to cover this.
---
 terraform/context_apply2_test.go             | 70 ++++++++++++++++++++
 terraform/node_resource_abstract_instance.go |  2 +-
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/terraform/context_apply2_test.go b/terraform/context_apply2_test.go
index cc3ee2f47..a9e816fc4 100644
--- a/terraform/context_apply2_test.go
+++ b/terraform/context_apply2_test.go
@@ -1 +1,71 @@
 package terraform
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform/addrs"
+	"github.com/hashicorp/terraform/providers"
+	"github.com/hashicorp/terraform/states"
+)
+
+// Test that the PreApply hook is called with the correct deposed key
+func TestContext2Apply_createBeforeDestroy_deposedKeyPreApply(t *testing.T) {
+	m := testModule(t, "apply-cbd-deposed-only")
+	p := testProvider("aws")
+	p.PlanResourceChangeFn = testDiffFn
+	p.ApplyResourceChangeFn = testApplyFn
+
+	deposedKey := states.NewDeposedKey()
+
+	state := states.NewState()
+	root := state.EnsureModule(addrs.RootModuleInstance)
+	root.SetResourceInstanceCurrent(
+		mustResourceInstanceAddr("aws_instance.bar").Resource,
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectReady,
+			AttrsJSON: []byte(`{"id":"bar"}`),
+		},
+		mustProviderConfig(`provider["registry.terraform.io/hashicorp/aws"]`),
+	)
+	root.SetResourceInstanceDeposed(
+		mustResourceInstanceAddr("aws_instance.bar").Resource,
+		deposedKey,
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectTainted,
+			AttrsJSON: []byte(`{"id":"foo"}`),
+		},
+		mustProviderConfig(`provider["registry.terraform.io/hashicorp/aws"]`),
+	)
+
+	hook := new(MockHook)
+	ctx := testContext2(t, &ContextOpts{
+		Config: m,
+		Hooks:  []Hook{hook},
+		Providers: map[addrs.Provider]providers.Factory{
+			addrs.NewDefaultProvider("aws"): testProviderFuncFixed(p),
+		},
+		State: state,
+	})
+
+	if p, diags := ctx.Plan(); diags.HasErrors() {
+		t.Fatalf("diags: %s", diags.Err())
+	} else {
+		t.Logf(legacyDiffComparisonString(p.Changes))
+	}
+
+	state, diags := ctx.Apply()
+	if diags.HasErrors() {
+		t.Fatalf("diags: %s", diags.Err())
+	}
+
+	// Verify PreApply was called correctly
+	if !hook.PreApplyCalled {
+		t.Fatalf("PreApply hook not called")
+	}
+	if addr, wantAddr := hook.PreApplyAddr, mustResourceInstanceAddr("aws_instance.bar"); !addr.Equal(wantAddr) {
+		t.Errorf("expected addr to be %s, but was %s", wantAddr, addr)
+	}
+	if gen := hook.PreApplyGen; gen != deposedKey {
+		t.Errorf("expected gen to be %q, but was %q", deposedKey, gen)
+	}
+}
diff --git a/terraform/node_resource_abstract_instance.go b/terraform/node_resource_abstract_instance.go
index 5bc1a4468..9a5892a92 100644
--- a/terraform/node_resource_abstract_instance.go
+++ b/terraform/node_resource_abstract_instance.go
@@ -221,7 +221,7 @@ func (n *NodeAbstractResourceInstance) preApplyHook(ctx EvalContext, change *pla
 		plannedNewState := change.After
 
 		diags = diags.Append(ctx.Hook(func(h Hook) (HookAction, error) {
-			return h.PreApply(n.Addr, nil, change.Action, priorState, plannedNewState)
+			return h.PreApply(n.Addr, change.DeposedKey.Generation(), change.Action, priorState, plannedNewState)
 		}))
 		if diags.HasErrors() {
 			return diags