terraform: depends_on can reference entire modules

terraform/context_apply_test.go

@@ -110,6 +110,142 @@ test = []`)
 	}
 }
 
+func TestContext2Apply_resourceDependsOnModule(t *testing.T) {
+	m := testModule(t, "apply-resource-depends-on-module")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+
+	{
+		// Wait for the dependency, sleep, and verify the graph never
+		// called a child.
+		var called int32
+		var checked bool
+		p.ApplyFn = func(
+			info *InstanceInfo,
+			is *InstanceState,
+			id *InstanceDiff) (*InstanceState, error) {
+			if info.HumanId() == "module.child.aws_instance.child" {
+				checked = true
+
+				// Sleep to allow parallel execution
+				time.Sleep(50 * time.Millisecond)
+
+				// Verify that called is 0 (dep not called)
+				if atomic.LoadInt32(&called) != 0 {
+					return nil, fmt.Errorf("aws_instance.a should not be called")
+				}
+			}
+
+			atomic.AddInt32(&called, 1)
+			return testApplyFn(info, is, id)
+		}
+
+		ctx := testContext2(t, &ContextOpts{
+			Module: m,
+			Providers: map[string]ResourceProviderFactory{
+				"aws": testProviderFuncFixed(p),
+			},
+		})
+
+		if _, err := ctx.Plan(); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		state, err := ctx.Apply()
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		if !checked {
+			t.Fatal("should check")
+		}
+
+		checkStateString(t, state, testTerraformApplyResourceDependsOnModuleStr)
+	}
+}
+
+func TestContext2Apply_resourceDependsOnModuleDestroy(t *testing.T) {
+	m := testModule(t, "apply-resource-depends-on-module")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+
+	var globalState *State
+	{
+		p.ApplyFn = testApplyFn
+		ctx := testContext2(t, &ContextOpts{
+			Module: m,
+			Providers: map[string]ResourceProviderFactory{
+				"aws": testProviderFuncFixed(p),
+			},
+		})
+
+		if _, err := ctx.Plan(); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		state, err := ctx.Apply()
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		globalState = state
+	}
+
+	{
+		// Wait for the dependency, sleep, and verify the graph never
+		// called a child.
+		var called int32
+		var checked bool
+		p.ApplyFn = func(
+			info *InstanceInfo,
+			is *InstanceState,
+			id *InstanceDiff) (*InstanceState, error) {
+			if info.HumanId() == "aws_instance.a" {
+				checked = true
+
+				// Sleep to allow parallel execution
+				time.Sleep(50 * time.Millisecond)
+
+				// Verify that called is 0 (dep not called)
+				if atomic.LoadInt32(&called) != 0 {
+					return nil, fmt.Errorf("module child should not be called")
+				}
+			}
+
+			atomic.AddInt32(&called, 1)
+			return testApplyFn(info, is, id)
+		}
+
+		ctx := testContext2(t, &ContextOpts{
+			Module: m,
+			Providers: map[string]ResourceProviderFactory{
+				"aws": testProviderFuncFixed(p),
+			},
+			State:   globalState,
+			Destroy: true,
+		})
+
+		if _, err := ctx.Plan(); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		state, err := ctx.Apply()
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		if !checked {
+			t.Fatal("should check")
+		}
+
+		checkStateString(t, state, `
+<no state>
+module.child:
+  <no state>
+		`)
+	}
+}
+
 func TestContext2Apply_mapVarBetweenModules(t *testing.T) {
 	m := testModule(t, "apply-map-var-through-module")
 	p := testProvider("null")

terraform/terraform_test.go

@@ -653,6 +653,18 @@ aws_instance.foo:
   num = 2
 `
 
+const testTerraformApplyResourceDependsOnModuleStr = `
+aws_instance.a:
+  ID = foo
+
+  Dependencies:
+    module.child
+
+module.child:
+  aws_instance.child:
+    ID = foo
+`
+
 const testTerraformApplyTaintStr = `
 aws_instance.bar:
   ID = foo

terraform/test-fixtures/apply-resource-depends-on-module/child/main.tf

@@ -0,0 +1 @@
+resource "aws_instance" "child" {}

terraform/test-fixtures/apply-resource-depends-on-module/main.tf

@@ -0,0 +1,7 @@
+module "child" {
+    source = "./child"
+}
+
+resource "aws_instance" "a" {
+    depends_on = ["module.child"]
+}

terraform/transform_reference.go

@@ -200,6 +200,15 @@ func NewReferenceMap(vs []dag.Vertex) *ReferenceMap {
 			n = prefix + n
 			refMap[n] = append(refMap[n], v)
 		}
+
+		// If there is a path, it is always referenceable by that. For
+		// example, if this is a referenceable thing at path []string{"foo"},
+		// then it can be referenced at "module.foo"
+		if pn, ok := v.(GraphNodeSubPath); ok {
+			if p := ReferenceModulePath(pn.Path()); p != "" {
+				refMap[p] = append(refMap[p], v)
+			}
+		}
 	}
 
 	// Build the lookup table for referenced by
@@ -224,6 +233,18 @@ func NewReferenceMap(vs []dag.Vertex) *ReferenceMap {
 	return &m
 }
 
+// Returns the reference name for a module path. The path "foo" would return
+// "module.foo"
+func ReferenceModulePath(p []string) string {
+	p = normalizeModulePath(p)
+	if len(p) == 1 {
+		// Root, no name
+		return ""
+	}
+
+	return fmt.Sprintf("module.%s", strings.Join(p[1:], "."))
+}
+
 // ReferencesFromConfig returns the references that a configuration has
 // based on the interpolated variables in a configuration.
 func ReferencesFromConfig(c *config.RawConfig) []string {