feat: do no execute pre/post update commands on linked containers

actions/update.go

@@ -48,9 +48,11 @@ func Update(client container.Client, filter container.Filter, cleanup bool, noRe
 			continue
 		}
 
-		if container.Stale {
+		if container.ToRestart() {
 
-			executePreUpdateCommand(enableUpdateCmd, client, container)
+                        if container.Stale {
+			        executePreUpdateCommand(enableUpdateCmd, client, container)
+                        }
 
 			if err := client.StopContainer(container, timeout); err != nil {
 				log.Error(err)
@@ -60,7 +62,7 @@ func Update(client container.Client, filter container.Filter, cleanup bool, noRe
 
 	// Restart stale containers in sorted order
 	for _, container := range containers {
-		if container.Stale {
+		if container.ToRestart() {
 			// 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
@@ -77,7 +79,7 @@ func Update(client container.Client, filter container.Filter, cleanup bool, noRe
 				newContainerID, err := client.StartContainer(container)
 				if err != nil {
 					log.Error(err)
-				} else {
+				} else if container.Stale {
 					executePostUpdateCommand(enableUpdateCmd, client, newContainerID)
 				}
 			}
@@ -128,15 +130,15 @@ func executePostUpdateCommand(enabled bool, client container.Client, newContaine
 func checkDependencies(containers []container.Container) {
 
 	for i, parent := range containers {
-		if parent.Stale {
+		if parent.ToRestart() {
 			continue
 		}
 
 	LinkLoop:
 		for _, linkName := range parent.Links() {
 			for _, child := range containers {
-				if child.Name() == linkName && child.Stale {
+				if child.Name() == linkName && child.ToRestart() {
-					containers[i].Stale = true
+					containers[i].Linked = true
 					break LinkLoop
 				}
 			}

container/container.go

@@ -29,6 +29,7 @@ func NewContainer(containerInfo *types.ContainerJSON, imageInfo *types.ImageInsp
 
 // Container represents a running Docker container.
 type Container struct {
+        Linked bool
 	Stale bool
 
 	containerInfo *types.ContainerJSON
@@ -141,6 +142,12 @@ func (c Container) PostUpdateCommand() string {
 	return ""
 }
 
+// ToRestart return whether the container should be restarted, either because
+// is stale or linked to another stale container.
+func (c Container) ToRestart() bool {
+        return c.Stale || c.Linked
+}
+
 // Ideally, we'd just be able to take the ContainerConfig from the old container
 // and use it as the starting point for creating the new container; however,
 // the ContainerConfig that comes back from the Inspect call merges the default

test/commands-test.sh

@@ -4,17 +4,20 @@ set -e
 
 IMAGE=server
 CONTAINER=server
+LINKED_IMAGE=linked
+LINKED_CONTAINER=linked
 WATCHTOWER_INTERVAL=2
 
 function remove_container {
-	docker kill $CONTAINER >> /dev/null || true && docker rm -v $CONTAINER >> /dev/null || true
+	docker kill $1 >> /dev/null || true && docker rm -v $1 >> /dev/null || true
 }
 
 function cleanup {
   # Do cleanup on exit or error
   echo "Final cleanup"
   sleep 2
-  remove_container
+  remove_container $CONTAINER
+  remove_container $LINKED_CONTAINER
   pkill -9 -f watchtower >> /dev/null || true
 }
 trap cleanup EXIT
@@ -73,7 +76,7 @@ function builddocker {
 
 # Start watchtower
 echo "Starting watchtower"
-$WATCHTOWER -i $WATCHTOWER_INTERVAL --no-pull --stop-timeout 2s --enable-update-commands $CONTAINER &
+$WATCHTOWER -i $WATCHTOWER_INTERVAL --no-pull --stop-timeout 2s --enable-update-commands $CONTAINER $LINKED_CONTAINER &
 sleep 3
 
 echo "#################################################################"
@@ -109,7 +112,7 @@ if [[ $RESP != "image" ]]; then
 	exit 1
 fi
 
-remove_container
+remove_container $CONTAINER
 
 echo "#################################################################"
 echo "##### TEST CASE 2: Execute commands from container and base image"
@@ -144,4 +147,62 @@ RESP=$(curl -s http://localhost:8888)
 if [[ $RESP != "container" ]]; then
 	echo "Value of container response is invalid. Expected: container. Actual: $RESP"
 	exit 1
+fi
+
+remove_container $CONTAINER
+
+echo "#################################################################"
+echo "##### TEST CASE 3: Execute commands with a linked container"
+echo "#################################################################"
+
+# Tag the current image to keep a version for the linked container
+docker tag $IMAGE:latest $LINKED_IMAGE:latest
+
+# Build base image
+builddocker
+
+# Run container
+docker run -d -p 0.0.0.0:8888:8888 \
+	--label=com.centurylinklabs.watchtower.post-update-command="echo container > /opt/test/value.txt" \
+	--name $CONTAINER $IMAGE:latest >> /dev/null
+docker run -d -p 0.0.0.0:8989:8888 \
+	--label=com.centurylinklabs.watchtower.post-update-command="echo container > /opt/test/value.txt" \
+	--link $CONTAINER \
+	--name $LINKED_CONTAINER $LINKED_IMAGE:latest >> /dev/null
+sleep 1
+echo "Container $CONTAINER and $LINKED_CONTAINER are runnning"
+
+# Test default value
+RESP=$(curl -s http://localhost:8888)
+if [ $RESP != "default" ]; then
+	echo "Default value of container response is invalid" 1>&2
+	exit 1
+fi
+
+# Test default value for linked container
+RESP=$(curl -s http://localhost:8989)
+if [ $RESP != "default" ]; then
+	echo "Default value of linked container response is invalid" 1>&2
+	exit 1
+fi
+
+# Build updated image to trigger watchtower update
+builddocker
+
+WAIT_AMOUNT=$(($WATCHTOWER_INTERVAL * 3))
+echo "Wait for $WAIT_AMOUNT seconds"
+sleep $WAIT_AMOUNT
+
+# Test value after post-update-command
+RESP=$(curl -s http://localhost:8888)
+if [[ $RESP != "container" ]]; then
+	echo "Value of container response is invalid. Expected: container. Actual: $RESP"
+	exit 1
+fi
+
+# Test that linked container did not execute pre/post-update-command
+RESP=$(curl -s http://localhost:8989)
+if [[ $RESP != "default" ]]; then
+	echo "Value of linked container response is invalid. Expected: default. Actual: $RESP"
+	exit 1
 fi