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Add documentation for how to register new StorageDrivers

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This commit adds context-specific documentation on StorageDriver,
StorageDriverFactory, and the factory’s Register func, explaining how
the internal registration mechanism should be used.

This documentation follows from the thread starting at
https://github.com/deis/builder/pull/262/files#r56720200.

cc/ @stevvooe

Signed-off-by: Aaron Schlesinger <aschlesinger@deis.com>
This commit is contained in:
Aaron Schlesinger 2016-03-18 16:28:42 -07:00
parent b787035d8b
commit 204ad474e4
2 changed files with 18 additions and 2 deletions
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11
registry/storage/driver/factory/factory.go
View file

@ -11,7 +11,14 @@ import (
var driverFactories = make(map[string]StorageDriverFactory) var driverFactories = make(map[string]StorageDriverFactory)
// StorageDriverFactory is a factory interface for creating storagedriver.StorageDriver interfaces // StorageDriverFactory is a factory interface for creating storagedriver.StorageDriver interfaces
// Storage drivers should call Register() with a factory to make the driver available by name // Storage drivers should call Register() with a factory to make the driver available by name.
// Individual StorageDriver implementations generally register with the factory via the Register
// func (below) in their init() funcs, and as such they should be imported anonymously before use.
// See below for an example of how to register and get a StorageDriver for S3
//
// import _ "github.com/docker/distribution/registry/storage/driver/s3-aws"
// s3Driver, err = factory.Create("s3", storageParams)
// // assuming no error, s3Driver is the StorageDriver that communicates with S3 according to storageParams
type StorageDriverFactory interface { type StorageDriverFactory interface {
// Create returns a new storagedriver.StorageDriver with the given parameters // Create returns a new storagedriver.StorageDriver with the given parameters
// Parameters will vary by driver and may be ignored // Parameters will vary by driver and may be ignored
@ -21,6 +28,8 @@ type StorageDriverFactory interface {
// Register makes a storage driver available by the provided name. // Register makes a storage driver available by the provided name.
// If Register is called twice with the same name or if driver factory is nil, it panics. // If Register is called twice with the same name or if driver factory is nil, it panics.
// Additionally, it is not concurrency safe. Most Storage Drivers call this function
// in their init() functions. See the documentation for StorageDriverFactory for more.
func Register(name string, factory StorageDriverFactory) { func Register(name string, factory StorageDriverFactory) {
if factory == nil { if factory == nil {
panic("Must not provide nil StorageDriverFactory") panic("Must not provide nil StorageDriverFactory")

9
registry/storage/driver/storagedriver.go
View file

@ -34,7 +34,14 @@ func (version Version) Minor() uint {
const CurrentVersion Version = "0.1" const CurrentVersion Version = "0.1"
// StorageDriver defines methods that a Storage Driver must implement for a // StorageDriver defines methods that a Storage Driver must implement for a
// filesystem-like key/value object storage. // filesystem-like key/value object storage. Storage Drivers are automatically
// registered via an internal registration mechanism, and generally created
// via the StorageDriverFactory interface (https://godoc.org/github.com/docker/distribution/registry/storage/driver/factory).
// See below for an example of how to get a StorageDriver for S3:
//
// import _ "github.com/docker/distribution/registry/storage/driver/s3-aws"
// s3Driver, err = factory.Create("s3", storageParams)
// // assuming no error, s3Driver is the StorageDriver that communicates with S3 according to storageParams
type StorageDriver interface { type StorageDriver interface {
// Name returns the human-readable "name" of the driver, useful in error // Name returns the human-readable "name" of the driver, useful in error
// messages and logging. By convention, this will just be the registration // messages and logging. By convention, this will just be the registration