docs/scheduler/filter/constraint.go

55 lines
1.4 KiB
Go

package filter
import (
"fmt"
log "github.com/Sirupsen/logrus"
"github.com/docker/swarm/cluster"
"github.com/samalba/dockerclient"
)
// ConstraintFilter selects only nodes that match certain labels.
type ConstraintFilter struct {
}
func (f *ConstraintFilter) Filter(config *dockerclient.ContainerConfig, nodes []*cluster.Node) ([]*cluster.Node, error) {
constraints := extractEnv("constraint", config.Env)
for k, v := range constraints {
log.Debugf("matching constraint: %s=%s", k, v)
negate := false
if strings.HasPrefix(v, "!") {
log.Debugf("negate detected")
v = strings.TrimPrefix(v, "!")
negate = true
}
candidates := []*cluster.Node{}
for _, node := range nodes {
switch k {
case "node":
// "node" label is a special case pinning a container to a specific node.
if match(v, node.ID) || match(v, node.Name) {
candidates = append(candidates, node)
}
default:
// By default match the node labels.
if label, ok := node.Labels[k]; ok {
if negate {
if f.match(v, label) == false {
candidates = append(candidates, node)
}
} else {
if f.match(v, label) {
candidates = append(candidates, node)
}
}
}
}
}
if len(candidates) == 0 {
return nil, fmt.Errorf("unable to find a node that satisfies %s == %s", k, v)
}
nodes = candidates
}
return nodes, nil
}