ca0084fad1
Custom storage drivers can register a factory to create the driver by name, similar to the database/sql package's Register and Open factory.Create returns an in-process driver if registered or an IPC driver if one can be found, erroring otherwise This standardizes parameter passing for creation of storage drivers Also adds documentation for storagedriver package and children
65 lines
2.3 KiB
Go
65 lines
2.3 KiB
Go
package factory
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import (
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"fmt"
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"github.com/docker/docker-registry/storagedriver"
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"github.com/docker/docker-registry/storagedriver/ipc"
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)
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// Internal mapping between storage driver names and their respective factories
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var driverFactories = make(map[string]StorageDriverFactory)
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// Factory interface for the storagedriver.StorageDriver interface
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// Storage drivers should call Register() with a factory to make the driver available by name
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type StorageDriverFactory interface {
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// Creates and returns a new storagedriver.StorageDriver with the given parameters
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// Parameters will vary by driver and may be ignored
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// Each parameter key must only consist of lowercase letters and numbers
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Create(parameters map[string]string) (storagedriver.StorageDriver, error)
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}
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// Register makes a storage driver available by the provided name.
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// If Register is called twice with the same name or if driver factory is nil, it panics.
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func Register(name string, factory StorageDriverFactory) {
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if factory == nil {
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panic("Must not provide nil StorageDriverFactory")
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}
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_, registered := driverFactories[name]
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if registered {
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panic(fmt.Sprintf("StorageDriverFactory named %s already registered", name))
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}
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driverFactories[name] = factory
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}
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// Create a new storagedriver.StorageDriver with the given name and parameters
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// To run in-process, the StorageDriverFactory must first be registered with the given name
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// If no in-process drivers are found with the given name, this attempts to create an IPC driver
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// If no in-process or external drivers are found, an InvalidStorageDriverError is returned
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func Create(name string, parameters map[string]string) (storagedriver.StorageDriver, error) {
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driverFactory, ok := driverFactories[name]
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if !ok {
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// No registered StorageDriverFactory found, try ipc
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driverClient, err := ipc.NewDriverClient(name, parameters)
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if err != nil {
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return nil, InvalidStorageDriverError{name}
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}
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err = driverClient.Start()
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if err != nil {
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return nil, err
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}
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return driverClient, nil
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}
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return driverFactory.Create(parameters)
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}
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// Error returned when attempting to construct an unregistered storage driver
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type InvalidStorageDriverError struct {
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Name string
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}
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func (err InvalidStorageDriverError) Error() string {
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return fmt.Sprintf("StorageDriver not registered: %s", err.Name)
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}
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