Refactoring & renaming

actions/update.go

@@ -0,0 +1,99 @@
+package actions
+
+import (
+	"math/rand"
+
+	"github.com/CenturyLinkLabs/watchtower/container"
+)
+
+var (
+	letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+)
+
+func allContainersFilter(container.Container) bool { return true }
+
+func Update() error {
+	client := container.NewClient()
+	containers, err := client.ListContainers(allContainersFilter)
+	if err != nil {
+		return err
+	}
+
+	for i := range containers {
+		if err := client.RefreshImage(&containers[i]); err != nil {
+			return err
+		}
+	}
+
+	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() {
+			break
+		}
+
+		if container.Stale {
+			if err := client.Stop(container, 10); err != nil {
+				return 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.Rename(container, randName()); err != nil {
+					return err
+				}
+			}
+
+			if err := client.Start(container); err != nil {
+				return err
+			}
+		}
+	}
+
+	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)
+}