package actions import ( "math/rand" "time" "github.com/CenturyLinkLabs/watchtower/container" log "github.com/Sirupsen/logrus" ) var ( letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ") waitTime = 10 * time.Second ) func allContainersFilter(container.Container) bool { return true } func containerFilter(names []string) container.Filter { if len(names) == 0 { return allContainersFilter } return func(c container.Container) bool { for _, name := range names { if (name == c.Name()) || (name == c.Name()[1:]) { return true } } return false } } // Update looks at the running Docker containers to see if any of the images // used to start those containers have been updated. If a change is detected in // any of the images, the associated containers are stopped and restarted with // the new image. func Update(client container.Client, names []string, cleanup bool) error { log.Info("Checking containers for updated images") containers, err := client.ListContainers(containerFilter(names)) if err != nil { return err } for i, container := range containers { stale, err := client.IsContainerStale(container) if err != nil { return err } containers[i].Stale = stale } containers, err = container.SortByDependencies(containers) if err != nil { return err } checkDependencies(containers) // Stop stale containers in reverse order for i := len(containers) - 1; i >= 0; i-- { container := containers[i] if container.IsWatchtower() { continue } if container.Stale { if err := client.StopContainer(container, waitTime); err != nil { log.Error(err) } } } // Restart stale containers in sorted order for _, container := range containers { if container.Stale { // Since we can't shutdown a watchtower container immediately, we need to // start the new one while the old one is still running. This prevents us // from re-using the same container name so we first rename the current // instance so that the new one can adopt the old name. if container.IsWatchtower() { if err := client.RenameContainer(container, randName()); err != nil { log.Error(err) continue } } if err := client.StartContainer(container); err != nil { log.Error(err) } if cleanup { client.RemoveImage(container) } } } return nil } func checkDependencies(containers []container.Container) { for i, parent := range containers { if parent.Stale { continue } LinkLoop: for _, linkName := range parent.Links() { for _, child := range containers { if child.Name() == linkName && child.Stale { containers[i].Stale = true break LinkLoop } } } } } // Generates a random, 32-character, Docker-compatible container name. func randName() string { b := make([]rune, 32) for i := range b { b[i] = letters[rand.Intn(len(letters))] } return string(b) }