From a1801b0ebe599b988724e05f2c5705ac8cd0b26c Mon Sep 17 00:00:00 2001 From: Mary Anthony Date: Tue, 28 Apr 2015 15:10:52 -0700 Subject: [PATCH] Fixing headings Signed-off-by: Mary Anthony (cherry picked from commit 7c93c8c265fe7cf1c59f857d7049c39902e854a0) --- docs/storagedrivers.md | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) diff --git a/docs/storagedrivers.md b/docs/storagedrivers.md index 2db67e282..e532d3a00 100644 --- a/docs/storagedrivers.md +++ b/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-\" 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.