errors: Create a new standard error for invalid config

Refactor a common error into a new standard error object.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

virtcontainers/kata_agent.go

@@ -189,7 +189,7 @@ func (k *kataAgent) init(ctx context.Context, sandbox *Sandbox, config interface
 		}
 		k.keepConn = c.LongLiveConn
 	default:
-		return fmt.Errorf("Invalid config type")
+		return vcTypes.ErrInvalidConfigType
 	}
 
 	k.proxy, err = newProxy(sandbox.config.ProxyType)
@@ -241,7 +241,7 @@ func (k *kataAgent) internalConfigure(h hypervisor, id, sharePath string, builti
 			}
 			k.keepConn = c.LongLiveConn
 		default:
-			return fmt.Errorf("Invalid config type")
+			return vcTypes.ErrInvalidConfigType
 		}
 	}
 
@@ -275,7 +275,7 @@ func (k *kataAgent) configure(h hypervisor, id, sharePath string, builtin bool,
 		}
 		k.vmSocket = s
 	default:
-		return fmt.Errorf("Invalid config type")
+		return vcTypes.ErrInvalidConfigType
 	}
 
 	// Neither create shared directory nor add 9p device if hypervisor

virtcontainers/pkg/types/errors.go

@@ -11,9 +11,10 @@ import (
 
 // common error objects used for argument checking
 var (
-	ErrNeedSandbox     = errors.New("Sandbox must be specified")
-	ErrNeedSandboxID   = errors.New("Sandbox ID cannot be empty")
-	ErrNeedContainerID = errors.New("Container ID cannot be empty")
-	ErrNeedState       = errors.New("State cannot be empty")
-	ErrNoSuchContainer = errors.New("Container does not exist")
+	ErrNeedSandbox       = errors.New("Sandbox must be specified")
+	ErrNeedSandboxID     = errors.New("Sandbox ID cannot be empty")
+	ErrNeedContainerID   = errors.New("Container ID cannot be empty")
+	ErrNeedState         = errors.New("State cannot be empty")
+	ErrNoSuchContainer   = errors.New("Container does not exist")
+	ErrInvalidConfigType = errors.New("Invalid config type")
 )