forked from TrueCloudLab/distribution
60 lines
3.4 KiB
Markdown
60 lines
3.4 KiB
Markdown
<!--[metadata]>
|
|
+++
|
|
title = "Docker Registry Storage Driver"
|
|
description = "Explains how to use the storage drivers"
|
|
keywords = ["registry, service, driver, images, storage"]
|
|
[menu.main]
|
|
parent="smn_registry_ref"
|
|
identifier="smn_registry_drivers"
|
|
+++
|
|
<![end-metadata]-->
|
|
|
|
|
|
# Docker Registry Storage Driver
|
|
|
|
This document describes the registry storage driver model, implementation, and explains how to contribute new storage drivers.
|
|
|
|
## Provided Drivers
|
|
|
|
This storage driver package comes bundled with several drivers:
|
|
|
|
- [inmemory](storage-drivers/inmemory.md): A temporary storage driver using a local inmemory map. This exists solely for reference and testing.
|
|
- [filesystem](storage-drivers/filesystem.md): A local storage driver configured to use a directory tree in the local filesystem.
|
|
- [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/).
|
|
- [rados](storage-drivers/rados.md): A driver storing objects in a [Ceph Object Storage](http://ceph.com/docs/master/rados/) pool.
|
|
- [swift](storage-drivers/swift): A driver storing objects in [Openstack Swift](http://docs.openstack.org/developer/swift/).
|
|
|
|
## 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.
|
|
|
|
Storage drivers are required to implement the `storagedriver.StorageDriver` interface provided in `storagedriver.go`, which includes methods for reading, writing, and deleting content, as well as listing child objects of a specified prefix key.
|
|
|
|
Storage drivers are intended to be written in Go, providing compile-time
|
|
validation of the `storagedriver.StorageDriver` interface.
|
|
|
|
## 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 such storage driver can be found,
|
|
`factory.Create` will return an `InvalidStorageDriverError`.
|
|
|
|
## Driver Contribution
|
|
|
|
### 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.
|
|
|
|
#### Registering
|
|
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.
|
|
|
|
## Testing
|
|
Storage driver test suites are provided in
|
|
`storagedriver/testsuites/testsuites.go` and may be used for any storage
|
|
driver written in Go. Tests can be registered using the `RegisterSuite`
|
|
function, which run the same set of tests for any registered drivers.
|