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package store
import (
"github.com/go-macaroon-bakery/macaroon-bakery/v3/bakery"
"github.com/juju/aclstore/v2"
"github.com/juju/utils/v2/debugstatus"
errgo "gopkg.in/errgo.v1"
"github.com/canonical/candid/meeting"
)
var backends = make(map[string]func(func(interface{}) error) (BackendFactory, error))
// Backend is the interface provided by a storage backend
// implementation. Backend instances should be closed after use.
type Backend interface {
// ProviderDataStore returns a new ProviderDataStore
// implementation that uses the backend.
ProviderDataStore() ProviderDataStore
// BakeryRootKeyStore returns a new bakery.RootKeyStore
// implementation that uses the backend.
BakeryRootKeyStore() bakery.RootKeyStore
// MeetingStore returns a new meeting.Store implementation
// that uses the backend.
MeetingStore() meeting.Store
// DebugStatusCheckerFuncs returns a set of
// debugstatus.CheckerFuncs that can be used to provide a status
// of the backend in the /debug/status endpoint.
DebugStatusCheckerFuncs() []debugstatus.CheckerFunc
// Store returns a new store.Store instance that uses
// the backend.
Store() Store
// ACLStore returns a new aclstore.Store that is used to provide
// ACLs for system functions.
ACLStore() aclstore.ACLStore
// Close closes the Backend instance.
Close()
}
// BackendFactory represents a value that can create new storage
// backend instances.
type BackendFactory interface {
NewBackend() (Backend, error)
}
// Register is used by storage backends to register a function
// that can be used to unmarshal parameters for a storage backend. When
// a storage backend with the given type is used, f will be called to
// unmarshal its parameters from YAML. Its argument will be an
// unmarshalYAML function that can be used to unmarshal the
// configuration parameters into its argument according to the rules
// specified in gopkg.in/yaml.v2, and it should return a function that
// can be used to create a storage backend.
func Register(storageType string, f func(func(interface{}) error) (BackendFactory, error)) {
backends[storageType] = f
}
// Config allows a storage instance to be unmarshaled from a YAML
// configuration file. The "type" field determines which registered
// backend is used for the unmarshaling.
type Config struct {
BackendFactory
}
func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
var t struct {
Type string
}
if err := unmarshal(&t); err != nil {
return errgo.Notef(err, "cannot unmarshal storage")
}
if storageUnmarshaler, ok := backends[t.Type]; ok {
bf, err := storageUnmarshaler(unmarshal)
if err != nil {
return errgo.Notef(err, "cannot unmarshal %s configuration", t.Type)
}
c.BackendFactory = bf
return err
}
return errgo.Newf("unrecognised storage backend type %q", t.Type)
}
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