From 52bc9a1055700221aa2b29a202512e4945524b58 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sat, 30 Aug 2014 17:25:34 -0700
Subject: [PATCH] core: check sets for computed [GH-247]

---
 CHANGELOG.md                                  |  3 ++
 terraform/context.go                          | 30 ++++++++++++++-----
 terraform/context_test.go                     | 23 ++++++++++++++
 terraform/terraform_test.go                   | 16 ++++++++++
 .../test-fixtures/plan-computed-list/main.tf  |  8 +++++
 5 files changed, 72 insertions(+), 8 deletions(-)
 create mode 100644 terraform/test-fixtures/plan-computed-list/main.tf

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8096421a3..935fd2c99 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,9 @@ BUG FIXES:
 
   * core: Configuration parses when identifier and '=' have no space. [GH-243]
   * core: `depends_on` with `count` generates the proper graph. [GH-244]
+  * core: Depending on a computed variable of a list type generates a
+      plan without failure. i.e. `${type.name.foos.0.bar}` where `foos`
+      is computed. [GH-247]
 
 ## 0.2.0 (August 28, 2014)
 
diff --git a/terraform/context.go b/terraform/context.go
index 568c02875..9f462a8dc 100644
--- a/terraform/context.go
+++ b/terraform/context.go
@@ -367,16 +367,30 @@ func (c *Context) computeResourceVariable(
 	}
 
 	attr, ok := r.Attributes[v.Field]
-	if !ok {
-		return "", fmt.Errorf(
-			"Resource '%s' does not have attribute '%s' "+
-				"for variable '%s'",
-			id,
-			v.Field,
-			v.FullKey())
+	if ok {
+		return attr, nil
 	}
 
-	return attr, nil
+	// We didn't find the exact field, so lets separate the dots
+	// and see if anything along the way is a computed set. i.e. if
+	// we have "foo.0.bar" as the field, check to see if "foo" is
+	// a computed list. If so, then the whole thing is computed.
+	parts := strings.Split(v.Field, ".")
+	if len(parts) > 1 {
+		for i := 1; i < len(parts); i++ {
+			key := fmt.Sprintf("%s.#", strings.Join(parts[:i], "."))
+			if attr, ok := r.Attributes[key]; ok {
+				return attr, nil
+			}
+		}
+	}
+
+	return "", fmt.Errorf(
+		"Resource '%s' does not have attribute '%s' "+
+			"for variable '%s'",
+		id,
+		v.Field,
+		v.FullKey())
 }
 
 func (c *Context) computeResourceMultiVariable(
diff --git a/terraform/context_test.go b/terraform/context_test.go
index 2557273ed..1b83e892f 100644
--- a/terraform/context_test.go
+++ b/terraform/context_test.go
@@ -1418,6 +1418,29 @@ func TestContextPlan_computed(t *testing.T) {
 	}
 }
 
+func TestContextPlan_computedList(t *testing.T) {
+	c := testConfig(t, "plan-computed-list")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Config: c,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanComputedListStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextPlan_count(t *testing.T) {
 	c := testConfig(t, "plan-count")
 	p := testProvider("aws")
diff --git a/terraform/terraform_test.go b/terraform/terraform_test.go
index b9392c0aa..7d89c3948 100644
--- a/terraform/terraform_test.go
+++ b/terraform/terraform_test.go
@@ -302,6 +302,22 @@ STATE:
 <no state>
 `
 
+const testTerraformPlanComputedListStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "<computed>"
+  type: "" => "aws_instance"
+CREATE: aws_instance.foo
+  list.#: "" => "<computed>"
+  num:    "" => "2"
+  type:   "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
 const testTerraformPlanCountStr = `
 DIFF:
 
diff --git a/terraform/test-fixtures/plan-computed-list/main.tf b/terraform/test-fixtures/plan-computed-list/main.tf
new file mode 100644
index 000000000..dd61d43f2
--- /dev/null
+++ b/terraform/test-fixtures/plan-computed-list/main.tf
@@ -0,0 +1,8 @@
+resource "aws_instance" "foo" {
+    num = "2"
+    compute = "list.#"
+}
+
+resource "aws_instance" "bar" {
+    foo = "${aws_instance.foo.list.0.bar}"
+}