compose/backend/backend.go

72 lines
1.5 KiB
Go

package backend
import (
"context"
"errors"
"fmt"
"github.com/sirupsen/logrus"
"github.com/docker/api/compose"
"github.com/docker/api/containers"
"github.com/docker/api/context/cloud"
)
var (
errNoType = errors.New("backend: no type")
errNoName = errors.New("backend: no name")
errTypeRegistered = errors.New("backend: already registered")
)
type initFunc func(context.Context) (Service, error)
type registeredBackend struct {
name string
backendType string
init initFunc
}
var backends = struct {
r []*registeredBackend
}{}
// Service aggregates the service interfaces
type Service interface {
ContainerService() containers.Service
ComposeService() compose.Service
CloudService() cloud.Service
}
// Register adds a typed backend to the registry
func Register(name string, backendType string, init initFunc) {
if name == "" {
logrus.Fatal(errNoName)
}
if backendType == "" {
logrus.Fatal(errNoType)
}
for _, b := range backends.r {
if b.backendType == backendType {
logrus.Fatal(errTypeRegistered)
}
}
backends.r = append(backends.r, &registeredBackend{
name,
backendType,
init,
})
}
// Get returns the backend registered for a particular type, it returns
// an error if there is no registered backends for the given type.
func Get(ctx context.Context, backendType string) (Service, error) {
for _, b := range backends.r {
if b.backendType == backendType {
return b.init(ctx)
}
}
return nil, fmt.Errorf("backend not found for context %q", backendType)
}