Merge pull request #464 from moxiegirl/adjust-storagedriver-heads

Fixing headings

docs/storagedrivers.md

@@ -1,10 +1,8 @@
-Docker-Registry Storage Driver
-==============================
+# Docker-Registry Storage Driver
 
 This document describes the registry storage driver model, implementation, and explains how to contribute new storage drivers.
 
-Provided Drivers
-================
+## Provided Drivers
 
 This storage driver package comes bundled with several drivers:
 
@@ -13,8 +11,7 @@ This storage driver package comes bundled with several drivers:
 - [s3](storage-drivers/s3.md): A driver storing objects in an Amazon Simple Storage Solution (S3) bucket.
 - [azure](storage-drivers/azure.md): A driver storing objects in [Microsoft Azure Blob Storage](http://azure.microsoft.com/en-us/services/storage/).
 
-Storage Driver API
-==================
+## Storage Driver API
 
 The storage driver API is designed to model a filesystem-like key/value storage in a manner abstract enough to support a range of drivers from the local filesystem to Amazon S3 or other distributed object storage systems.
 
@@ -22,23 +19,21 @@ Storage drivers are required to implement the `storagedriver.StorageDriver` inte
 
 Storage drivers are intended (but not required) to be written in go, providing compile-time validation of the `storagedriver.StorageDriver` interface, although an IPC driver wrapper means that it is not required for drivers to be included in the compiled registry. The `storagedriver/ipc` package provides a client/server protocol for running storage drivers provided in external executables as a managed child server process.
 
-Driver Selection and Configuration
-==================================
+## Driver Selection and Configuration
 
 The preferred method of selecting a storage driver is using the `StorageDriverFactory` interface in the `storagedriver/factory` package. These factories provide a common interface for constructing storage drivers with a parameters map. The factory model is based off of the [Register](http://golang.org/pkg/database/sql/#Register) and [Open](http://golang.org/pkg/database/sql/#Open) methods in the builtin [database/sql](http://golang.org/pkg/database/sql) package.
 
 Storage driver factories may be registered by name using the `factory.Register` method, and then later invoked by calling `factory.Create` with a driver name and parameters map. If no driver is registered with the given name, this factory will attempt to find an executable storage driver with the executable name "registry-storage-\<driver name\>" and return an IPC storage driver wrapper managing the driver subprocess. If no such storage driver can be found, `factory.Create` will return an `InvalidStorageDriverError`.
 
-Driver Contribution
-===================
+## Driver Contribution
 
-## Writing new storage drivers
+### Writing new storage drivers
 To create a valid storage driver, one must implement the `storagedriver.StorageDriver` interface and make sure to expose this driver via the factory system and as a distributable IPC server executable.
 
-### In-process drivers
+#### In-process drivers
 Storage drivers should call `factory.Register` with their driver name in an `init` method, allowing callers of `factory.New` to construct instances of this driver without requiring modification of imports throughout the codebase.
 
-### Out-of-process drivers
+#### Out-of-process drivers
 As many users will run the registry as a pre-constructed docker container, storage drivers should also be distributable as IPC server executables. Drivers written in go should model the main method provided in `storagedriver/filesystem/registry-storage-filesystem/filesystem.go`. Parameters to IPC drivers will be provided as a JSON-serialized map in the first argument to the process. These parameters should be validated and then a blocking call to `ipc.StorageDriverServer` should be made with a new storage driver.
 
 Out-of-process drivers must also implement the `ipc.IPCStorageDriver` interface, which exposes a `Version` check for the storage driver. This is used to validate storage driver api compatibility at driver load-time.