Improve documentation and golint compliance of registry package

* Add godoc documentation where it was missing

* Change identifier names that don't match Go style, such as INDEX_NAME

* Rename RegistryInfo to PingResult, which more accurately describes
  what this structure is for. It also has the benefit of making the name
  not stutter if used outside the package.

Updates #14756

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

docs/types.go

@@ -1,38 +1,66 @@
 package registry
 
+// SearchResult describes a search result returned from a registry
 type SearchResult struct {
-	StarCount   int    `json:"star_count"`
-	IsOfficial  bool   `json:"is_official"`
-	Name        string `json:"name"`
-	IsTrusted   bool   `json:"is_trusted"`
-	IsAutomated bool   `json:"is_automated"`
+	// StarCount indicates the number of stars this repository has
+	StarCount int `json:"star_count"`
+	// IsOfficial indicates whether the result is an official repository or not
+	IsOfficial bool `json:"is_official"`
+	// Name is the name of the repository
+	Name string `json:"name"`
+	// IsOfficial indicates whether the result is trusted
+	IsTrusted bool `json:"is_trusted"`
+	// IsAutomated indicates whether the result is automated
+	IsAutomated bool `json:"is_automated"`
+	// Description is a textual description of the repository
 	Description string `json:"description"`
 }
 
+// SearchResults lists a collection search results returned from a registry
 type SearchResults struct {
-	Query      string         `json:"query"`
-	NumResults int            `json:"num_results"`
-	Results    []SearchResult `json:"results"`
+	// Query contains the query string that generated the search results
+	Query string `json:"query"`
+	// NumResults indicates the number of results the query returned
+	NumResults int `json:"num_results"`
+	// Results is a slice containing the acutal results for the search
+	Results []SearchResult `json:"results"`
 }
 
+// RepositoryData tracks the image list, list of endpoints, and list of tokens
+// for a repository
 type RepositoryData struct {
-	ImgList   map[string]*ImgData
+	// ImgList is a list of images in the repository
+	ImgList map[string]*ImgData
+	// Endpoints is a list of endpoints returned in X-Docker-Endpoints
 	Endpoints []string
-	Tokens    []string
+	// Tokens is currently unused (remove it?)
+	Tokens []string
 }
 
+// ImgData is used to transfer image checksums to and from the registry
 type ImgData struct {
+	// ID is an opaque string that identifies the image
 	ID              string `json:"id"`
 	Checksum        string `json:"checksum,omitempty"`
 	ChecksumPayload string `json:"-"`
 	Tag             string `json:",omitempty"`
 }
 
-type RegistryInfo struct {
-	Version    string `json:"version"`
-	Standalone bool   `json:"standalone"`
+// PingResult contains the information returned when pinging a registry. It
+// indicates the registry's version and whether the registry claims to be a
+// standalone registry.
+type PingResult struct {
+	// Version is the registry version supplied by the registry in a HTTP
+	// header
+	Version string `json:"version"`
+	// Standalone is set to true if the registry indicates it is a
+	// standalone registry in the X-Docker-Registry-Standalone
+	// header
+	Standalone bool `json:"standalone"`
 }
 
+// APIVersion is an integral representation of an API version (presently
+// either 1 or 2)
 type APIVersion int
 
 func (av APIVersion) String() string {
@@ -51,6 +79,8 @@ const (
 	APIVersion2
 )
 
+// IndexInfo contains information about a registry
+//
 // RepositoryInfo Examples:
 // {
 //   "Index" : {
@@ -64,7 +94,7 @@ const (
 //   "CanonicalName" : "docker.io/debian"
 //   "Official" : true,
 // }
-
+//
 // {
 //   "Index" : {
 //     "Name" : "127.0.0.1:5000",
@@ -78,16 +108,33 @@ const (
 //   "Official" : false,
 // }
 type IndexInfo struct {
-	Name     string
-	Mirrors  []string
-	Secure   bool
+	// Name is the name of the registry, such as "docker.io"
+	Name string
+	// Mirrors is a list of mirrors, expressed as URIs
+	Mirrors []string
+	// Secure is set to false if the registry is part of the list of
+	// insecure registries. Insecure registries accept HTTP and/or accept
+	// HTTPS with certificates from unknown CAs.
+	Secure bool
+	// Official indicates whether this is an official registry
 	Official bool
 }
 
+// RepositoryInfo describes a repository
 type RepositoryInfo struct {
-	Index         *IndexInfo
-	RemoteName    string
-	LocalName     string
+	// Index points to registry information
+	Index *IndexInfo
+	// RemoteName is the remote name of the repository, such as
+	// "library/ubuntu-12.04-base"
+	RemoteName string
+	// LocalName is the local name of the repository, such as
+	// "ubuntu-12.04-base"
+	LocalName string
+	// CanonicalName is the canonical name of the repository, such as
+	// "docker.io/library/ubuntu-12.04-base"
 	CanonicalName string
-	Official      bool
+	// Official indicates whether the repository is considered official.
+	// If the registry is official, and the normalized name does not
+	// contain a '/' (e.g. "foo"), then it is considered an official repo.
+	Official bool
 }