Synnefo » snf-ganeti » ganeti-local

    , tryEvac

-- | Change an instance's secondary node.

evacInstance :: (Monad m) =>

                [Ndx]                      -- ^ Excluded nodes

             -> Instance.List              -- ^ The current instance list

             -> (Node.List, AllocSolution) -- ^ The current state

             -> Idx                        -- ^ The instance to evacuate

             -> m (Node.List, AllocSolution)

evacInstance ex_ndx il (nl, old_as) idx = do

  -- FIXME: hardcoded one node here

  -- Longer explanation: evacuation is currently hardcoded to DRBD

  -- instances (which have one secondary); hence, even if the

  -- IAllocator protocol can request N nodes for an instance, and all

  -- the message parsing/loading pass this, this implementation only

  -- supports one; this situation needs to be revisited if we ever

  -- support more than one secondary, or if we change the storage

  -- model

  new_as <- tryReloc nl il idx 1 ex_ndx

  case asSolutions new_as of

    -- an individual relocation succeeded, we kind of compose the data

    -- from the two solutions

    csol@(nl', _, _, _):_ ->

        return (nl', new_as { asSolutions = csol:asSolutions old_as })

    -- this relocation failed, so we fail the entire evac

    _ -> fail $ "Can't evacuate instance " ++

         Instance.name (Container.find idx il) ++

             ": " ++ describeSolution new_as

-- | Try to evacuate a list of nodes.

tryEvac :: (Monad m) =>

            Node.List       -- ^ The node list

         -> Instance.List   -- ^ The instance list

         -> [Idx]           -- ^ Instances to be evacuated

         -> [Ndx]           -- ^ Restricted nodes (the ones being evacuated)

         -> m AllocSolution -- ^ Solution list

tryEvac nl il idxs ex_ndx = do

  (_, sol) <- foldM (evacInstance ex_ndx il) (nl, emptyAllocSolution) idxs

  return sol

                   in case Cluster.tryEvac xnl il' [Instance.idx xi] [sdx] of

                        Just _ -> True