terraform: outputs are computed for the state

terraform/context.go

@@ -105,6 +105,18 @@ func (c *Context) Apply() (*State, error) {
 	// Update our state, even if we have an error, for partial updates
 	c.state = s
 
+	// If we have no errors, then calculate the outputs if we have any
+	if err == nil && len(c.config.Outputs) > 0 {
+		s.Outputs = make(map[string]string)
+		for _, o := range c.config.Outputs {
+			if err = c.computeVars(s, o.RawConfig); err != nil {
+				break
+			}
+
+			s.Outputs[o.Name] = o.RawConfig.Config()["value"].(string)
+		}
+	}
+
 	return s, err
 }
 
@@ -232,6 +244,48 @@ func (c *Context) Validate() ([]string, []error) {
 	return warns, errs
 }
 
+// computeVars takes the State and given RawConfig and processes all
+// the variables. This dynamically discovers the attributes instead of
+// using a static map[string]string that the genericWalkFn uses.
+func (c *Context) computeVars(s *State, raw *config.RawConfig) error {
+	// If there are on variables, then we're done
+	if len(raw.Variables) == 0 {
+		return nil
+	}
+
+	// Go through each variable and find it
+	vs := make(map[string]string)
+	for n, rawV := range raw.Variables {
+		switch v := rawV.(type) {
+		case *config.ResourceVariable:
+			r, ok := s.Resources[v.ResourceId()]
+			if !ok {
+				return fmt.Errorf(
+					"Resource '%s' not found for variable '%s'",
+					v.ResourceId(),
+					v.FullKey())
+			}
+
+			attr, ok := r.Attributes[v.Field]
+			if !ok {
+				return fmt.Errorf(
+					"Resource '%s' does not have attribute '%s' "+
+						"for variable '%s'",
+					v.ResourceId(),
+					v.Field,
+					v.FullKey())
+			}
+
+			vs[n] = attr
+		case *config.UserVariable:
+			vs[n] = c.variables[v.Name]
+		}
+	}
+
+	// Interpolate the variables
+	return raw.Interpolate(vs)
+}
+
 func (c *Context) graph() (*depgraph.Graph, error) {
 	return Graph(&GraphOpts{
 		Config:    c.config,

terraform/context_test.go

@@ -508,6 +508,34 @@ func TestContextApply_hook(t *testing.T) {
 	}
 }
 
+func TestContextApply_output(t *testing.T) {
+	c := testConfig(t, "apply-output")
+	p := testProvider("aws")
+	p.ApplyFn = testApplyFn
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Config: c,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	if _, err := ctx.Plan(nil); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	state, err := ctx.Apply()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(state.String())
+	expected := strings.TrimSpace(testTerraformApplyOutputStr)
+	if actual != expected {
+		t.Fatalf("bad: \n%s", actual)
+	}
+}
+
 func TestContextApply_unknownAttribute(t *testing.T) {
 	c := testConfig(t, "apply-unknown")
 	p := testProvider("aws")

terraform/state.go

@@ -16,6 +16,7 @@ import (
 // can use to keep track of what real world resources it is actually
 // managing.
 type State struct {
+	Outputs   map[string]string
 	Resources map[string]*ResourceState
 
 	once sync.Once
@@ -96,6 +97,21 @@ func (s *State) String() string {
 		}
 	}
 
+	if len(s.Outputs) > 0 {
+		buf.WriteString("\nOutputs:\n\n")
+
+		ks := make([]string, 0, len(s.Outputs))
+		for k, _ := range s.Outputs {
+			ks = append(ks, k)
+		}
+		sort.Strings(ks)
+
+		for _, k := range ks {
+			v := s.Outputs[k]
+			buf.WriteString(fmt.Sprintf("%s = %s\n", k, v))
+		}
+	}
+
 	return buf.String()
 }
 

terraform/terraform_test.go

@@ -106,6 +106,21 @@ aws_instance.foo:
   num = 2
 `
 
+const testTerraformApplyOutputStr = `
+aws_instance.bar:
+  ID = foo
+  foo = bar
+  type = aws_instance
+aws_instance.foo:
+  ID = foo
+  num = 2
+  type = aws_instance
+
+Outputs:
+
+foo_num = 2
+`
+
 const testTerraformApplyUnknownAttrStr = `
 aws_instance.foo:
   ID = foo

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

@@ -0,0 +1,11 @@
+resource "aws_instance" "foo" {
+    num = "2"
+}
+
+resource "aws_instance" "bar" {
+    foo = "bar"
+}
+
+output "foo_num" {
+    value = "${aws_instance.foo.num}"
+}