terraform: apply diff before apply

terraform/resource.go

@@ -1,5 +1,9 @@
 package terraform
 
+import (
+	"fmt"
+)
+
 // Resource encapsulates a resource, its configuration, its provider,
 // its current state, and potentially a desired diff from the state it
 // wants to reach.
@@ -10,3 +14,17 @@ type Resource struct {
 	Provider ResourceProvider
 	State    *ResourceState
 }
+
+// TODO: test
+func (r *Resource) Vars() map[string]string {
+	if r.State == nil {
+		return nil
+	}
+
+	vars := make(map[string]string)
+	for ak, av := range r.State.Attributes {
+		vars[fmt.Sprintf("%s.%s", r.Id, ak)] = av
+	}
+
+	return vars
+}

terraform/terraform.go

@@ -102,6 +102,13 @@ func (t *Terraform) Refresh(c *config.Config, s *State) (*State, error) {
 func (t *Terraform) apply(
 	g *depgraph.Graph,
 	p *Plan) (*State, error) {
+	if err := GraphAddDiff(g, p.Diff); err != nil {
+		return nil, err
+	}
+	if err := g.Validate(); err != nil {
+		return nil, err
+	}
+
 	s := new(State)
 	err := g.Walk(t.applyWalkFn(s, p))
 	return s, err
@@ -170,11 +177,9 @@ func (t *Terraform) applyWalkFn(
 	result.init()
 
 	cb := func(r *Resource) (map[string]string, error) {
-		diff, ok := p.Diff.Resources[r.Id]
-		if !ok {
-			// Skip if there is no diff for a resource
-			log.Printf("[DEBUG] No diff for %s, skipping.", r.Id)
-			return nil, nil
+		diff := r.Diff
+		if diff.Empty() {
+			return r.Vars(), nil
 		}
 
 		if !diff.Destroy {
@@ -229,23 +234,21 @@ func (t *Terraform) applyWalkFn(
 		result.Resources[r.Id] = rs
 		l.Unlock()
 
+		// Update the state for the resource itself
+		r.State = rs
+
 		for _, h := range t.hooks {
 			// TODO: return value
 			h.PostApply(r.Id, r.State)
 		}
 
 		// Determine the new state and update variables
-		vars := make(map[string]string)
-		for ak, av := range rs.Attributes {
-			vars[fmt.Sprintf("%s.%s", r.Id, ak)] = av
-		}
-
 		err = nil
 		if len(errs) > 0 {
 			err = &MultiError{Errors: errs}
 		}
 
-		return vars, err
+		return r.Vars(), err
 	}
 
 	return t.genericWalkFn(p.Vars, cb)
@@ -298,17 +301,11 @@ func (t *Terraform) planWalkFn(result *Plan, opts *PlanOpts) depgraph.WalkFunc {
 		}
 
 		// Determine the new state and update variables
-		vars := make(map[string]string)
 		if !diff.Empty() {
 			r.State = r.State.MergeDiff(diff)
 		}
-		if r.State != nil {
-			for ak, av := range r.State.Attributes {
-				vars[fmt.Sprintf("%s.%s", r.Id, ak)] = av
-			}
-		}
 
-		return vars, nil
+		return r.Vars(), nil
 	}
 
 	return t.genericWalkFn(opts.Vars, cb)

terraform/terraform_test.go

@@ -493,7 +493,7 @@ func testProviderFunc(n string, rs []string) ResourceProviderFactory {
 			}
 
 			id := "foo"
-			if idAttr, ok := d.Attributes["id"]; ok {
+			if idAttr, ok := d.Attributes["id"]; ok && !idAttr.NewComputed {
 				id = idAttr.New
 			}
 
@@ -687,12 +687,12 @@ const testTerraformApplyComputeStr = `
 aws_instance.bar:
   ID = foo
   type = aws_instance
-  foo = computed_id
+  foo = computed_dynamical
 aws_instance.foo:
   ID = foo
   type = aws_instance
   num = 2
-  id = computed_id
+  dynamical = computed_dynamical
 `
 
 const testTerraformApplyDestroyStr = `

terraform/test-fixtures/apply-compute/main.tf

@@ -1,9 +1,9 @@
 resource "aws_instance" "foo" {
     num = "2"
-    compute = "id"
+    compute = "dynamical"
     compute_value = "${var.value}"
 }
 
 resource "aws_instance" "bar" {
-    foo = "${aws_instance.foo.id}"
+    foo = "${aws_instance.foo.dynamical}"
 }