Comment more packages to pass go lint

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

plugin/context.go

@@ -9,7 +9,8 @@ import (
 	"github.com/containerd/containerd/log"
 )
 
-func NewContext(ctx context.Context, plugins map[PluginType]map[string]interface{}, root, state, id string) *InitContext {
+// NewContext returns a new plugin InitContext
+func NewContext(ctx context.Context, plugins map[Type]map[string]interface{}, root, state, id string) *InitContext {
 	return &InitContext{
 		plugins: plugins,
 		Root:    filepath.Join(root, id),
@@ -18,6 +19,7 @@ func NewContext(ctx context.Context, plugins map[PluginType]map[string]interface
 	}
 }
 
+// InitContext is used for plugin inititalization
 type InitContext struct {
 	Root    string
 	State   string
@@ -26,17 +28,19 @@ type InitContext struct {
 	Config  interface{}
 	Events  *events.Exchange
 
-	plugins map[PluginType]map[string]interface{}
+	plugins map[Type]map[string]interface{}
 }
 
-func (i *InitContext) Get(t PluginType) (interface{}, error) {
+// Get returns the first plugin by its type
+func (i *InitContext) Get(t Type) (interface{}, error) {
 	for _, v := range i.plugins[t] {
 		return v, nil
 	}
 	return nil, fmt.Errorf("no plugins registered for %s", t)
 }
 
-func (i *InitContext) GetAll(t PluginType) (map[string]interface{}, error) {
+// GetAll returns all plugins with the specific type
+func (i *InitContext) GetAll(t Type) (map[string]interface{}, error) {
 	p, ok := i.plugins[t]
 	if !ok {
 		return nil, fmt.Errorf("no plugins registered for %s", t)

plugin/differ.go

@@ -6,6 +6,7 @@ import (
 	"golang.org/x/net/context"
 )
 
+// Differ allows the apply and creation of filesystem diffs between mounts
 type Differ interface {
 	Apply(ctx context.Context, desc ocispec.Descriptor, mount []mount.Mount) (ocispec.Descriptor, error)
 	DiffMounts(ctx context.Context, lower, upper []mount.Mount, media, ref string) (ocispec.Descriptor, error)

plugin/plugin.go

@@ -9,49 +9,62 @@ import (
 )
 
 var (
-	ErrNoPluginType = errors.New("plugin: no type")
-	ErrNoPluginID   = errors.New("plugin: no id")
+	// ErrNoType is returned when no type is specified
+	ErrNoType = errors.New("plugin: no type")
+	// ErrNoPluginID is returned when no id is specified
+	ErrNoPluginID = errors.New("plugin: no id")
 
-	// SkipPlugin is used when a plugin is not initialized and should not be loaded,
+	// ErrSkipPlugin is used when a plugin is not initialized and should not be loaded,
 	// this allows the plugin loader differentiate between a plugin which is configured
 	// not to load and one that fails to load.
-	SkipPlugin = errors.New("skip plugin")
+	ErrSkipPlugin = errors.New("skip plugin")
 )
 
 // IsSkipPlugin returns true if the error is skipping the plugin
 func IsSkipPlugin(err error) bool {
-	if errors.Cause(err) == SkipPlugin {
+	if errors.Cause(err) == ErrSkipPlugin {
 		return true
 	}
 	return false
 }
 
-type PluginType string
+// Type is the type of the plugin
+type Type string
 
 const (
-	RuntimePlugin     PluginType = "io.containerd.runtime.v1"
-	GRPCPlugin        PluginType = "io.containerd.grpc.v1"
-	SnapshotPlugin    PluginType = "io.containerd.snapshotter.v1"
-	TaskMonitorPlugin PluginType = "io.containerd.monitor.v1"
-	DiffPlugin        PluginType = "io.containerd.differ.v1"
-	MetadataPlugin    PluginType = "io.containerd.metadata.v1"
-	ContentPlugin     PluginType = "io.containerd.content.v1"
+	// RuntimePlugin implements a runtime
+	RuntimePlugin Type = "io.containerd.runtime.v1"
+	// GRPCPlugin implements a grpc service
+	GRPCPlugin Type = "io.containerd.grpc.v1"
+	// SnapshotPlugin implements a snapshotter
+	SnapshotPlugin Type = "io.containerd.snapshotter.v1"
+	// TaskMonitorPlugin implements a task monitor
+	TaskMonitorPlugin Type = "io.containerd.monitor.v1"
+	// DiffPlugin implements a differ
+	DiffPlugin Type = "io.containerd.differ.v1"
+	// MetadataPlugin implements a metadata store
+	MetadataPlugin Type = "io.containerd.metadata.v1"
+	// ContentPlugin implements a content store
+	ContentPlugin Type = "io.containerd.content.v1"
 )
 
+// Registration contains information for registering a plugin
 type Registration struct {
-	Type     PluginType
+	Type     Type
 	ID       string
 	Config   interface{}
-	Requires []PluginType
+	Requires []Type
 	Init     func(*InitContext) (interface{}, error)
 
 	added bool
 }
 
+// URI returns the full plugin URI
 func (r *Registration) URI() string {
 	return fmt.Sprintf("%s.%s", r.Type, r.ID)
 }
 
+// Service allows GRPC services to be registered with the underlying server
 type Service interface {
 	Register(*grpc.Server) error
 }
@@ -75,11 +88,12 @@ func Load(path string) (err error) {
 	return loadPlugins(path)
 }
 
+// Register allows plugins to register
 func Register(r *Registration) {
 	register.Lock()
 	defer register.Unlock()
 	if r.Type == "" {
-		panic(ErrNoPluginType)
+		panic(ErrNoType)
 	}
 	if r.ID == "" {
 		panic(ErrNoPluginID)
@@ -87,6 +101,7 @@ func Register(r *Registration) {
 	register.r = append(register.r, r)
 }
 
+// Graph returns an ordered list of registered plugins for initialization
 func Graph() (ordered []*Registration) {
 	for _, r := range register.r {
 		children(r.Requires, &ordered)
@@ -98,7 +113,7 @@ func Graph() (ordered []*Registration) {
 	return ordered
 }
 
-func children(types []PluginType, ordered *[]*Registration) {
+func children(types []Type, ordered *[]*Registration) {
 	for _, t := range types {
 		for _, r := range register.r {
 			if r.Type == t {