github.com/mika/distribution@v2.2.2-0.20160108133430-a75790e3d8e0+incompatible/registry/middleware/repository/middleware.go (about)

     1  package middleware
     2  
     3  import (
     4  	"fmt"
     5  
     6  	"github.com/docker/distribution"
     7  	"github.com/docker/distribution/context"
     8  )
     9  
    10  // InitFunc is the type of a RepositoryMiddleware factory function and is
    11  // used to register the constructor for different RepositoryMiddleware backends.
    12  type InitFunc func(ctx context.Context, repository distribution.Repository, options map[string]interface{}) (distribution.Repository, error)
    13  
    14  var middlewares map[string]InitFunc
    15  
    16  // Register is used to register an InitFunc for
    17  // a RepositoryMiddleware backend with the given name.
    18  func Register(name string, initFunc InitFunc) error {
    19  	if middlewares == nil {
    20  		middlewares = make(map[string]InitFunc)
    21  	}
    22  	if _, exists := middlewares[name]; exists {
    23  		return fmt.Errorf("name already registered: %s", name)
    24  	}
    25  
    26  	middlewares[name] = initFunc
    27  
    28  	return nil
    29  }
    30  
    31  // Get constructs a RepositoryMiddleware with the given options using the named backend.
    32  func Get(ctx context.Context, name string, options map[string]interface{}, repository distribution.Repository) (distribution.Repository, error) {
    33  	if middlewares != nil {
    34  		if initFunc, exists := middlewares[name]; exists {
    35  			return initFunc(ctx, repository, options)
    36  		}
    37  	}
    38  
    39  	return nil, fmt.Errorf("no repository middleware registered with name: %s", name)
    40  }