README
¶
page_title: Docker Swarm strategies page_description: Swarm strategies page_keywords: docker, swarm, clustering, strategies
Strategies
The Docker Swarm scheduler comes with multiple strategies.
These strategies are used to rank nodes using a scores computed by the strategy.
Docker Swarm currently supports 2 strategies:
You can choose the strategy you want to use with the --strategy flag of swarm manage
BinPacking strategy
The BinPacking strategy will rank the nodes using their CPU and RAM available and will return the node the most packed already. This avoid fragmentation, it will leave room for bigger containers on unused machines.
For instance, let's says that both node-1 and node-2 have 2G of RAM:
$ docker run -d -P -m 1G --name db mysql
f8b693db9cd6
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NODE NAMES
f8b693db9cd6 mysql:latest "mysqld" Less than a second ago running 192.168.0.42:49178->3306/tcp node-1 db
In this case, node-1 was chosen randomly, because no container were running, so node-1 and
node-2 had the same score.
Now we start another container, asking for 1G of RAM again.
$ docker run -d -P -m 1G --name frontend nginx
963841b138d8
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NODE NAMES
963841b138d8 nginx:latest "nginx" Less than a second ago running 192.168.0.42:49177->80/tcp node-1 frontend
f8b693db9cd6 mysql:latest "mysqld" Up About a minute running 192.168.0.42:49178->3306/tcp node-1 db
The container frontend was also started on node-1 because it was the node the most packed
already. This allows us to start a container requiring 2G of RAM on node-2.
Random strategy
The Random strategy, as it's name says, chooses a random node, it's used mainly for debug.
Docker Swarm documentation index
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrNotSupported = errors.New("strategy not supported") ErrNoResourcesAvailable = errors.New("no resources available to schedule container") )
Functions ¶
This section is empty.
Types ¶
type BinpackPlacementStrategy ¶ added in v0.2.0
type BinpackPlacementStrategy struct {
}
func (*BinpackPlacementStrategy) Initialize ¶ added in v0.2.0
func (p *BinpackPlacementStrategy) Initialize() error
func (*BinpackPlacementStrategy) PlaceContainer ¶ added in v0.2.0
func (p *BinpackPlacementStrategy) PlaceContainer(config *dockerclient.ContainerConfig, nodes []cluster.Node) (cluster.Node, error)
type PlacementStrategy ¶
type PlacementStrategy interface {
Initialize() error
// Given a container configuration and a set of nodes, select the target
// node where the container should be scheduled.
PlaceContainer(config *dockerclient.ContainerConfig, nodes []cluster.Node) (cluster.Node, error)
}
func New ¶
func New(name string) (PlacementStrategy, error)
type RandomPlacementStrategy ¶
type RandomPlacementStrategy struct{}
Randomly place the container into the cluster.
func (*RandomPlacementStrategy) Initialize ¶
func (p *RandomPlacementStrategy) Initialize() error
func (*RandomPlacementStrategy) PlaceContainer ¶
func (p *RandomPlacementStrategy) PlaceContainer(config *dockerclient.ContainerConfig, nodes []cluster.Node) (cluster.Node, error)
type SpreadPlacementStrategy ¶ added in v0.2.0
type SpreadPlacementStrategy struct {
}
func (*SpreadPlacementStrategy) Initialize ¶ added in v0.2.0
func (p *SpreadPlacementStrategy) Initialize() error
func (*SpreadPlacementStrategy) PlaceContainer ¶ added in v0.2.0
func (p *SpreadPlacementStrategy) PlaceContainer(config *dockerclient.ContainerConfig, nodes []cluster.Node) (cluster.Node, error)
Source Files