Fix container downtime

internal/actions/actions_suite_test.go

@@ -57,7 +57,8 @@ var _ = Describe("the actions package", func() {
 						"test-container",
 						"test-container",
 						"watchtower",
-						time.Now()),
+						time.Now(),
+						make([]string,0)),
 				}
 				err := actions.CheckForMultipleWatchtowerInstances(client, false, "")
 				Expect(err).NotTo(HaveOccurred())
@@ -75,12 +76,14 @@ var _ = Describe("the actions package", func() {
 								"test-container-01",
 								"test-container-01",
 								"watchtower",
-								time.Now().AddDate(0, 0, -1)),
+								time.Now().AddDate(0, 0, -1),
+								make([]string,0),),
 							CreateMockContainer(
 								"test-container-02",
 								"test-container-02",
 								"watchtower",
-								time.Now()),
+								time.Now(),
+								make([]string,0)),
 						},
 					},
 					dockerClient,
@@ -106,12 +109,14 @@ var _ = Describe("the actions package", func() {
 								"test-container-01",
 								"test-container-01",
 								"watchtower",
-								time.Now().AddDate(0, 0, -1)),
+								time.Now().AddDate(0, 0, -1),
+								make([]string,0),),
 							CreateMockContainer(
 								"test-container-02",
 								"test-container-02",
 								"watchtower",
-								time.Now()),
+								time.Now(),
+								make([]string,0),),
 						},
 					},
 					dockerClient,

internal/actions/mocks/client.go

@@ -22,6 +22,8 @@ type TestData struct {
 	TriedToRemoveImageCount int
 	NameOfContainerToKeep   string
 	Containers              []container.Container
+	StopOrder				[]string
+	RestartOrder			[]string
 }
 
 // TriedToRemoveImage is a test helper function to check whether RemoveImageByID has been called
@@ -49,11 +51,13 @@ func (client MockClient) StopContainer(c container.Container, d time.Duration) e
 	if c.Name() == client.TestData.NameOfContainerToKeep {
 		return errors.New("tried to stop the instance we want to keep")
 	}
+	client.TestData.StopOrder = append(client.TestData.StopOrder, c.Name())
 	return nil
 }
 
 // StartContainer is a mock method
 func (client MockClient) StartContainer(c container.Container) (string, error) {
+	client.TestData.RestartOrder = append(client.TestData.RestartOrder, c.Name())
 	return "", nil
 }
 

internal/actions/mocks/container.go

@@ -8,7 +8,7 @@ import (
 )
 
 // CreateMockContainer creates a container substitute valid for testing
-func CreateMockContainer(id string, name string, image string, created time.Time) container.Container {
+func CreateMockContainer(id string, name string, image string, created time.Time, depends []string) container.Container {
 	content := types.ContainerJSON{
 		ContainerJSONBase: &types.ContainerJSONBase{
 			ID:      id,
@@ -20,6 +20,15 @@ func CreateMockContainer(id string, name string, image string, created time.Time
 			Labels: make(map[string]string),
 		},
 	}
+	dependencyString := ""
+	for ind, i := range depends {
+		if ind == 0 {
+			dependencyString += i;
+		}else{
+			dependencyString += "," + i;
+		}
+	}
+	content.Config.Labels["com.centurylinklabs.watchtower.depends-on"] = dependencyString
 	return *container.NewContainer(
 		&content,
 		&types.ImageInspect{

internal/actions/update.go

@@ -10,20 +10,36 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-// 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, params types.UpdateParams) error {
-	log.Debug("Checking containers for updated images")
+// CreateUndirectedLinks creates a map of undirected links
+// Key: Name of a container
+// Value: List of containers that are linked to the container
+// i.e if Container A depends on B, undirectedNodes['A'] will initially contain B.
+// This function adds 'A' into undirectedNodes['B'] to make the link undirected.
+func CreateUndirectedLinks(containers []container.Container) map[string][]string {
 
-	if params.LifecycleHooks {
-		lifecycle.ExecutePreChecks(client, params)
+	undirectedNodes := make(map[string][]string)
+	for i:= 0; i < len(containers); i++ {
+		undirectedNodes[containers[i].Name()] = containers[i].Links()
+	}
+
+	for i:= 0; i< len(containers); i++ {
+		for j:=0; j < len(containers[i].Links()); j++ {
+			undirectedNodes[containers[i].Links()[j]] = append(undirectedNodes[containers[i].Links()[j]], containers[i].Name())
+		}
 	}
 
+	return undirectedNodes;
+}
+
+// PrepareContainerList prepares a dependency sorted list of list of containers
+// Each list inside the outer list contains containers that are related by links
+// This method checks for staleness, checks dependencies, sorts the containers and returns the final
+// [][]container.Container
+func PrepareContainerList(client container.Client, params types.UpdateParams) ([]container.Container, error) {
+
 	containers, err := client.ListContainers(params.Filter)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	for i, targetContainer := range containers {
@@ -38,31 +54,67 @@ func Update(client container.Client, params types.UpdateParams) error {
 		containers[i].Stale = stale
 	}
 
-	containers, err = sorter.SortByDependencies(containers)
+	checkDependencies(containers)
+
+	return containers, nil
+}
+
+// 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, params types.UpdateParams) error {
+	log.Debug("Checking containers for updated images")
+
+	if params.LifecycleHooks {
+		lifecycle.ExecutePreChecks(client, params)
+	}
+
+	containers, err := PrepareContainerList(client, params)
 	if err != nil {
 		return err
 	}
 
-	checkDependencies(containers)
-
 	containersToUpdate := []container.Container{}
 	if !params.MonitorOnly {
-		for i := len(containers) - 1; i >= 0; i-- {
+		for i := 0; i < len(containers); i++ {
 			if !containers[i].IsMonitorOnly() {
 				containersToUpdate = append(containersToUpdate, containers[i])
 			}
 		}
 	}
 
+	//shared map for independent and linked update
+	imageIDs := make(map[string]bool)
+
 	if params.RollingRestart {
 		performRollingRestart(containersToUpdate, client, params)
 	} else {
-		stopContainersInReversedOrder(containersToUpdate, client, params)
-		restartContainersInSortedOrder(containersToUpdate, client, params)
+		var dependencySortedGraphs [][]container.Container
+
+		undirectedNodes := CreateUndirectedLinks(containersToUpdate)
+		dependencySortedGraphs, err := sorter.SortByDependencies(containersToUpdate,undirectedNodes)
+
+		if err != nil {
+			return err
+		}
+
+		//Use ordered start and stop for each independent set of containers
+		for _, dependencyGraph:= range dependencySortedGraphs {
+			stopContainersInReversedOrder(dependencyGraph, client, params)
+			restartContainersInSortedOrder(dependencyGraph, client, params, imageIDs)
+		}
+
+		//clean up after containers updated
+		if params.Cleanup {
+			cleanupImages(client,imageIDs)
+		}
 	}
+
 	if params.LifecycleHooks {
 		lifecycle.ExecutePostChecks(client, params)
 	}
+
 	return nil
 }
 
@@ -109,19 +161,13 @@ func stopStaleContainer(container container.Container, client container.Client,
 	}
 }
 
-func restartContainersInSortedOrder(containers []container.Container, client container.Client, params types.UpdateParams) {
-	imageIDs := make(map[string]bool)
-
-	for _, staleContainer := range containers {
-		if !staleContainer.Stale {
+func restartContainersInSortedOrder(containers []container.Container, client container.Client, params types.UpdateParams, imageIDs map[string]bool) {
+	for _, container := range containers {
+		if !container.Stale {
 			continue
 		}
-		restartStaleContainer(staleContainer, client, params)
-		imageIDs[staleContainer.ImageID()] = true
-	}
-
-	if params.Cleanup {
-		cleanupImages(client, imageIDs)
+		restartStaleContainer(container, client, params)
+		imageIDs[container.ImageID()] = true
 	}
 }
 
@@ -171,4 +217,4 @@ func checkDependencies(containers []container.Container) {
 			}
 		}
 	}
-}
+}