docs/scheduler/filter/constraint.go

54 lines
1.4 KiB
Go

package filter
import (
"fmt"
log "github.com/Sirupsen/logrus"
"github.com/docker/swarm/cluster"
"github.com/docker/swarm/scheduler/node"
)
// ConstraintFilter selects only nodes that match certain labels.
type ConstraintFilter struct {
}
// Name returns the name of the filter
func (f *ConstraintFilter) Name() string {
return "constraint"
}
// Filter is exported
func (f *ConstraintFilter) Filter(config *cluster.ContainerConfig, nodes []*node.Node) ([]*node.Node, error) {
constraints, err := parseExprs(config.Constraints())
if err != nil {
return nil, err
}
for _, constraint := range constraints {
log.Debugf("matching constraint: %s %s %s", constraint.key, OPERATORS[constraint.operator], constraint.value)
candidates := []*node.Node{}
for _, node := range nodes {
switch constraint.key {
case "node":
// "node" label is a special case pinning a container to a specific node.
if constraint.Match(node.ID, node.Name) {
candidates = append(candidates, node)
}
default:
if constraint.Match(node.Labels[constraint.key]) {
candidates = append(candidates, node)
}
}
}
if len(candidates) == 0 {
if constraint.isSoft {
continue
}
return nil, fmt.Errorf("unable to find a node that satisfies %s%s%s", constraint.key, OPERATORS[constraint.operator], constraint.value)
}
nodes = candidates
}
return nodes, nil
}