terraform: calculate outputs and store it into the state

terraform/context_test.go

@@ -396,7 +396,6 @@ func TestContext2Plan_moduleProviderDefaultsVar(t *testing.T) {
 	}
 }
 
-/*
 func TestContext2Plan_moduleVar(t *testing.T) {
 	m := testModule(t, "plan-module-var")
 	p := testProvider("aws")

terraform/eval_output.go

@@ -0,0 +1,60 @@
+package terraform
+
+import (
+	"fmt"
+)
+
+// EvalWriteOutput is an EvalNode implementation that writes the output
+// for the given name to the current state.
+type EvalWriteOutput struct {
+	Name  string
+	Value EvalNode
+}
+
+func (n *EvalWriteOutput) Args() ([]EvalNode, []EvalType) {
+	return []EvalNode{n.Value}, []EvalType{EvalTypeConfig}
+}
+
+// TODO: test
+func (n *EvalWriteOutput) Eval(
+	ctx EvalContext, args []interface{}) (interface{}, error) {
+	config := args[0].(*ResourceConfig)
+
+	state, lock := ctx.State()
+	if state == nil {
+		return nil, fmt.Errorf("cannot write state to nil state")
+	}
+
+	// Get a write lock so we can access this instance
+	lock.Lock()
+	defer lock.Unlock()
+
+	// Look for the module state. If we don't have one, create it.
+	mod := state.ModuleByPath(ctx.Path())
+	if mod == nil {
+		mod = state.AddModule(ctx.Path())
+	}
+
+	// Get the value from the config
+	valueRaw, ok := config.Get("value")
+	if !ok {
+		valueRaw = ""
+	}
+
+	// If it is a list of values, get the first one
+	if list, ok := valueRaw.([]interface{}); ok {
+		valueRaw = list[0]
+	}
+	if _, ok := valueRaw.(string); !ok {
+		valueRaw = ""
+	}
+
+	// Write the output
+	mod.Outputs[n.Name] = valueRaw.(string)
+
+	return nil, nil
+}
+
+func (n *EvalWriteOutput) Type() EvalType {
+	return EvalTypeNull
+}

terraform/graph_config_node.go

@@ -122,7 +122,13 @@ func (n *GraphNodeConfigOutput) DependentOn() []string {
 
 // GraphNodeEvalable impl.
 func (n *GraphNodeConfigOutput) EvalTree() EvalNode {
-	return nil
+	return &EvalOpFilter{
+		Ops: []walkOperation{walkRefresh, walkPlan},
+		Node: &EvalWriteOutput{
+			Name:  n.Output.Name,
+			Value: &EvalInterpolate{Config: n.Output.RawConfig},
+		},
+	}
 }
 
 // GraphNodeConfigProvider represents a configured provider within the