env: Move each component into a separate struct

This commit cleans up the distillery code by making each component a
distinct struct. Each of these components is also returned by by a new
Component() function that replaces the Stacks() function.

env/stack.go

@@ -9,20 +9,31 @@ import (
 // TODO: Move everything into specific subpackages
 
 // Stacks returns the Stacks of this distillery
-func (dis *Distillery) Stacks() []stack.Installable {
+func (dis *Distillery) Components() []Component {
 	// TODO: Do we want to cache these stacks?
-	return []stack.Installable{
-		dis.WebStack(),
-		dis.SelfStack(),
-		dis.ResolverStack(),
-		dis.SSHStack(),
-		dis.TriplestoreStack(),
-		dis.SQLStack(),
+	return []Component{
+		dis.Web(),
+		dis.Self(),
+		dis.Resolver(),
+		dis.SSH(),
+		dis.Triplestore(),
+		dis.SQL(),
 	}
 }
 
+// Component represents a component of the distillery
+type Component interface {
+	Name() string // Name is the name of this component
+
+	Stack() stack.Installable // Stack returns the installable stack representing this component
+
+	Path() string // Path returns the path to this component
+}
+
 // asCoreStack treats the provided stack as a core component of this distillery.
-func (dis *Distillery) asCoreStack(name string, stack stack.Installable) stack.Installable {
+func (dis *Distillery) makeComponentStack(component Component, stack stack.Installable) stack.Installable {
+	name := component.Name()
+
 	stack.Dir = filepath.Join(dis.Config.DeployRoot, "core", name)
 
 	stack.ContextResource = filepath.Join("resources", "compose", name)