Project the core Mufile types

This change adds the core Mufile types (Cluster, Stack, and friends), including
mapping them to the relevant JSON names in the serialized form.  Notably absent
are all of the Identity-related types, which will come later on.

pkg/api/types.go

@@ -0,0 +1,74 @@
+// Copyright 2016 Marapongo, Inc. All rights reserved.
+
+// The API package contains the core Mu types.
+// TODO: several core types still need to be mapped:
+//     - Schema
+//     - Identity: User, Role, Group
+//     - Configuration
+//     - Secret
+package api
+
+// Name is an identifier.  Names may be optionally fully qualified, using the delimiter `/`, or simple.  Each element
+// conforms to the regex [A-Za-z_][A-Za-z0-9_]*.  For example, `marapongo/mu/stack`.
+type Name string
+
+// Semver represents a version using "semantic versioning" style.  This may include up to three distinct numbers
+// delimited by `.`s: a major version number, a minor version number, and a revision number.  For example, `1.0.10`.
+type Semver string
+
+// Meta contains human-readable metadata common to Mu's packaging formats (like Stacks and Clusters).
+type Meta struct {
+	Name        Name   `json:"name,omitempty"`
+	Version     Semver `json:"version,omitempty"`
+	Description string `json:"description,omitempty"`
+	Author      string `json:"author,omitempty"`
+	Website     string `json:"website,omitempty"`
+	License     string `json:"license,omitempty"`
+}
+
+// Stack represents a collection of private and public cloud resources, a method for constructing them, and optional
+// dependencies on other Stacks (by name).
+type Stack struct {
+	Meta
+	Parameters   Parameters   `json:"parameters,omitempty"`
+	Public       Services     `json:"public,omitempty"`
+	Private      Services     `json:"private,omitempty"`
+	Dependencies Dependencies `json:"dependencies,omitempty"`
+}
+
+// Parameters maps parameter names to metadata about those parameters.
+type Parameters map[string]Parameter
+
+// Parameter describes the requirements of arguments used when constructing Stacks, etc.
+type Parameter struct {
+	Description string      `json:"description,omitempty"`
+	Type        Name        `json:"type,omitempty"`
+	Default     interface{} `json:"default,omitempty"`
+	Optional    bool        `json:"optional,omitempty"`
+}
+
+// Services maps service names to metadata about those services.
+type Services map[string]Service
+
+// Service is a directive for instantiating another Stack, including its name, arguments, etc.
+// TODO: Service metadata is highly extensible.  It's not yet clear how best to represent this.
+type Service struct {
+	Type Name `json:"type,omitempty"`
+}
+
+// Dependencies maps dependency names to the semantic version the consumer depends on.
+type Dependencies map[string]Semver
+
+// Cluster describes a cluster of many Stacks, in addition to other metadata, like predefined Targets.
+type Cluster struct {
+	Meta
+	Targets map[string]Target `json:"targets,omitempty"`
+}
+
+// Target describes a predefined cloud runtime target, including its OS and Scheduler combination.
+type Target struct {
+	Description    string `json:"description,omitempty"`
+	CloudOS        string `json:"infra,omitempty"`
+	CloudScheduler string `json:"containers,omitempty"`
+	// TODO(joe): configuration.
+}