fix depends on behavior and simplify some of its logic (#908)

* fix depends on behavior and simplify some of its logic

* fix comments

internal/actions/check.go

@@ -2,28 +2,47 @@ package actions
 
 import (
 	"fmt"
+	"github.com/containrrr/watchtower/pkg/types"
 	"sort"
 	"time"
 
 	"github.com/containrrr/watchtower/pkg/filters"
 	"github.com/containrrr/watchtower/pkg/sorter"
-	"github.com/sirupsen/logrus"
 
 	log "github.com/sirupsen/logrus"
 
 	"github.com/containrrr/watchtower/pkg/container"
 )
 
+// CheckForSanity makes sure everything is sane before starting
+func CheckForSanity(client container.Client, filter types.Filter, rollingRestarts bool) error {
+	log.Debug("Making sure everything is sane before starting")
+
+	if rollingRestarts {
+		containers, err := client.ListContainers(filter)
+		if err != nil {
+			return err
+		}
+		for _, c := range containers {
+			if len(c.Links()) > 0 {
+				return fmt.Errorf(
+					"%q is depending on at least one other container. This is not compatible with rolling restarts",
+					c.Name(),
+				)
+			}
+		}
+	}
+	return nil
+}
+
 // CheckForMultipleWatchtowerInstances will ensure that there are not multiple instances of the
 // watchtower running simultaneously. If multiple watchtower containers are detected, this function
 // will stop and remove all but the most recently started container. This behaviour can be bypassed
 // if a scope UID is defined.
 func CheckForMultipleWatchtowerInstances(client container.Client, cleanup bool, scope string) error {
-	awaitDockerClient()
 	containers, err := client.ListContainers(filters.FilterByScope(scope, filters.WatchtowerContainersFilter))
 
 	if err != nil {
-		log.Fatal(err)
 		return err
 	}
 
@@ -45,14 +64,14 @@ func cleanupExcessWatchtowers(containers []container.Container, client container
 	for _, c := range allContainersExceptLast {
 		if err := client.StopContainer(c, 10*time.Minute); err != nil {
 			// logging the original here as we're just returning a count
-			logrus.WithError(err).Error("Could not stop a previous watchtower instance.")
+			log.WithError(err).Error("Could not stop a previous watchtower instance.")
 			stopErrors++
 			continue
 		}
 
 		if cleanup {
 			if err := client.RemoveImageByID(c.ImageID()); err != nil {
-				logrus.WithError(err).Warning("Could not cleanup watchtower images, possibly because of other watchtowers instances in other scopes.")
+				log.WithError(err).Warning("Could not cleanup watchtower images, possibly because of other watchtowers instances in other scopes.")
 			}
 		}
 	}
@@ -63,8 +82,3 @@ func cleanupExcessWatchtowers(containers []container.Container, client container
 
 	return nil
 }
-
-func awaitDockerClient() {
-	log.Debug("Sleeping for a second to ensure the docker api client has been properly initialized.")
-	time.Sleep(1 * time.Second)
-}

internal/actions/update.go

@@ -50,6 +50,7 @@ func Update(client container.Client, params types.UpdateParams) (*metrics2.Metri
 	}
 
 	containers, err = sorter.SortByDependencies(containers)
+
 	metric.Scanned = len(containers)
 	if err != nil {
 		return nil, err
@@ -57,11 +58,11 @@ func Update(client container.Client, params types.UpdateParams) (*metrics2.Metri
 
 	checkDependencies(containers)
 
-	containersToUpdate := []container.Container{}
+	var containersToUpdate []container.Container
 	if !params.MonitorOnly {
-		for i := len(containers) - 1; i >= 0; i-- {
-			if !containers[i].IsMonitorOnly() {
-				containersToUpdate = append(containersToUpdate, containers[i])
+		for _, c := range containers {
+			if !c.IsMonitorOnly() {
+				containersToUpdate = append(containersToUpdate, c)
 			}
 		}
 	}
@@ -86,7 +87,7 @@ func performRollingRestart(containers []container.Container, client container.Cl
 	failed := 0
 
 	for i := len(containers) - 1; i >= 0; i-- {
-		if containers[i].Stale {
+		if containers[i].ToRestart() {
 			if err := stopStaleContainer(containers[i], client, params); err != nil {
 				failed++
 			}
@@ -119,7 +120,7 @@ func stopStaleContainer(container container.Container, client container.Client,
 		return nil
 	}
 
-	if !container.Stale {
+	if !container.ToRestart() {
 		return nil
 	}
 	if params.LifecycleHooks {
@@ -143,7 +144,7 @@ func restartContainersInSortedOrder(containers []container.Container, client con
 	failed := 0
 
 	for _, c := range containers {
-		if !c.Stale {
+		if !c.ToRestart() {
 			continue
 		}
 		if err := restartStaleContainer(c, client, params); err != nil {
@@ -183,7 +184,7 @@ func restartStaleContainer(container container.Container, client container.Clien
 		if newContainerID, err := client.StartContainer(container); err != nil {
 			log.Error(err)
 			return err
-		} else if container.Stale && params.LifecycleHooks {
+		} else if container.ToRestart() && params.LifecycleHooks {
 			lifecycle.ExecutePostUpdateCommand(client, newContainerID)
 		}
 	}
@@ -192,16 +193,19 @@ func restartStaleContainer(container container.Container, client container.Clien
 
 func checkDependencies(containers []container.Container) {
 
-	for i, parent := range containers {
-		if parent.ToRestart() {
+	for _, c := range containers {
+		if c.ToRestart() {
 			continue
 		}
 
 	LinkLoop:
-		for _, linkName := range parent.Links() {
-			for _, child := range containers {
-				if child.Name() == linkName && child.ToRestart() {
-					containers[i].Linked = true
+		for _, linkName := range c.Links() {
+			for _, candidate := range containers {
+				if candidate.Name() != linkName {
+					continue
+				}
+				if candidate.ToRestart() {
+					c.LinkedToRestarting = true
 					break LinkLoop
 				}
 			}