terraform: some files laying out an API

terraform/diff.go

@@ -0,0 +1,16 @@
+package terraform
+
+// Diff tracks the differences between resources to apply.
+type Diff struct {
+	resources map[string]map[string]*resourceDiff
+}
+
+// resourceDiff is the diff of a single attribute of a resource.
+//
+// This tracks the old value, the new value, and whether the change of this
+// value actually requires an entirely new resource.
+type resourceDiff struct {
+	Old         string
+	New         string
+	RequiresNew bool
+}

terraform/resource_provider.go

@@ -19,3 +19,7 @@ type ResourceProvider interface {
 type ResourceType struct {
 	Name string
 }
+
+// ResourceProviderFactory is a function type that creates a new instance
+// of a resource provider.
+type ResourceProviderFactory func() (ResourceProvider, error)

terraform/state.go

@@ -0,0 +1,20 @@
+package terraform
+
+// State keeps track of a snapshot state-of-the-world that Terraform
+// can use to keep track of what real world resources it is actually
+// managing.
+type State struct {
+	resources map[string]resourceState
+}
+
+// resourceState is the state of a single resource.
+//
+// The ID is required and is some opaque string used to recognize
+// the realized resource.
+//
+// Extra is arbitrary extra metadata that the resource provider returns
+// that is sent back into the resource provider when it is needed.
+type resourceState struct {
+	ID    string
+	Extra map[string]interface{}
+}

terraform/terraform.go

@@ -0,0 +1,43 @@
+package terraform
+
+import (
+	"github.com/hashicorp/terraform/config"
+)
+
+// Terraform is the primary structure that is used to interact with
+// Terraform from code, and can perform operations such as returning
+// all resources, a resource tree, a specific resource, etc.
+type Terraform struct {
+	config    *config.Config
+	providers []ResourceProvider
+}
+
+// Config is the configuration that must be given to instantiate
+// a Terraform structure.
+type Config struct {
+	Config    *config.Config
+	Providers map[string]ResourceProviderFactory
+	Variables map[string]string
+}
+
+// New creates a new Terraform structure, initializes resource providers
+// for the given configuration, etc.
+//
+// Semantic checks of the entire configuration structure are done at this
+// time, as well as richer checks such as verifying that the resource providers
+// can be properly initialized, can be configured, etc.
+func New(c *Config) (*Terraform, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Apply(*State, *Diff) (*State, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Diff(*State) (*Diff, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Refresh(*State) (*State, error) {
+	return nil, nil
+}