// containerNextState determines the next state a container should go to.
// It returns: The state it should transition to, a bool indicating whether any
// action is required, and a bool indicating whether a known status change is
// possible.
// 'Stopped, false, true' -> "You can move it to known stopped, but you don't have to call a transition function"
// 'Running, true, true' -> "You can move it to running and you need to call the transition function"
// 'None, false, false' -> "This should not be moved; it has unresolved dependencies or is complete; no knownstatus change"
func (mtask *managedTask) containerNextState(container *api.Container) (api.ContainerStatus, bool, bool) {
clog := log.New("task", mtask.Task, "container", container)
containerKnownStatus := container.GetKnownStatus()
containerDesiredStatus := container.GetDesiredStatus()
if containerKnownStatus == containerDesiredStatus {
clog.Debug("Container at desired status", "desired", containerDesiredStatus)
return api.ContainerStatusNone, false, false
}
if containerKnownStatus > containerDesiredStatus {
clog.Debug("Container past desired status")
return api.ContainerStatusNone, false, false
}
if !dependencygraph.DependenciesAreResolved(container, mtask.Containers) {
clog.Debug("Can't apply state to container yet; dependencies unresolved", "state", containerDesiredStatus)
return api.ContainerStatusNone, false, false
}
var nextState api.ContainerStatus
if container.DesiredTerminal() {
nextState = api.ContainerStopped
if containerKnownStatus != api.ContainerRunning {
// If it's not currently running we do not need to do anything to make it become stopped.
return nextState, false, true
}
} else {
nextState = containerKnownStatus + 1
}
return nextState, true, true
}
func linkIsResolved(target *api.Container, link *api.Container) bool {
targetDesiredStatus := target.GetDesiredStatus()
if targetDesiredStatus == api.ContainerCreated {
knownStatus := link.GetKnownStatus()
return knownStatus == api.ContainerCreated || knownStatus == api.ContainerRunning
} else if targetDesiredStatus == api.ContainerRunning {
return link.GetKnownStatus() == api.ContainerRunning
}
log.Error("Unexpected desired status", "target", target)
return false
}
func volumeIsResolved(target *api.Container, volume *api.Container) bool {
targetDesiredStatus := target.GetDesiredStatus()
if targetDesiredStatus == api.ContainerCreated || targetDesiredStatus == api.ContainerRunning {
knownStatus := volume.GetKnownStatus()
return knownStatus == api.ContainerCreated ||
knownStatus == api.ContainerRunning ||
knownStatus == api.ContainerStopped
}
log.Error("Unexpected desired status", "target", target)
return false
}
// verifyStatusResolveable validates that `target` can be resolved given that
// target depends on `dependencies` (which are container names) and there are
// `existingContainers` (map from name to container). The `resolves` function
// passed should return true if the named container is resolved.
func verifyStatusResolveable(target *api.Container, existingContainers map[string]*api.Container, dependencies []string, resolves func(*api.Container, *api.Container) bool) bool {
targetGoal := target.GetDesiredStatus()
if targetGoal != api.ContainerRunning && targetGoal != api.ContainerCreated {
// A container can always stop, die, or reach whatever other statre it
// wants regardless of what dependencies it has
return true
}
for _, dependency := range dependencies {
maybeResolves, exists := existingContainers[dependency]
if !exists {
return false
}
if !resolves(target, maybeResolves) {
return false
}
}
return true
}
// onRunIsResolved defines a relationship where a target cannot be created until
// 'run' has reached a running state.
func onRunIsResolved(target *api.Container, run *api.Container) bool {
if target.GetDesiredStatus() >= api.ContainerCreated {
return run.GetKnownStatus() >= api.ContainerRunning
}
return false
}