Add a label take precedence argument

cmd/root.go

@@ -39,6 +39,7 @@ var (
 	lifecycleHooks  bool
 	rollingRestart  bool
 	scope           string
+	labelPrecedence bool
 )
 
 var rootCmd = NewRootCommand()
@@ -109,6 +110,7 @@ func PreRun(cmd *cobra.Command, _ []string) {
 	lifecycleHooks, _ = f.GetBool("enable-lifecycle-hooks")
 	rollingRestart, _ = f.GetBool("rolling-restart")
 	scope, _ = f.GetString("scope")
+	labelPrecedence, _ = f.GetBool("label-take-precedence")
 
 	if scope != "" {
 		log.Debugf(`Using scope %q`, scope)
@@ -366,6 +368,7 @@ func runUpdatesWithNotifications(filter t.Filter) *metrics.Metric {
 		MonitorOnly:     monitorOnly,
 		LifecycleHooks:  lifecycleHooks,
 		RollingRestart:  rollingRestart,
+		LabelPrecedence: labelPrecedence,
 	}
 	result, err := actions.Update(client, updateParams)
 	if err != nil {

docs/arguments.md

@@ -205,7 +205,7 @@ Environment Variable: WATCHTOWER_POLL_INTERVAL
 ```
 
 ## Filter by enable label
-Update containers that have a `com.centurylinklabs.watchtower.enable` label set to true.
+Monitor and update containers that have a `com.centurylinklabs.watchtower.enable` label set to true.
 
 ```text
             Argument: --label-enable
@@ -215,7 +215,7 @@ Environment Variable: WATCHTOWER_LABEL_ENABLE
 ```
 
 ## Filter by disable label
-__Do not__ update containers that have `com.centurylinklabs.watchtower.enable` label set to false and 
+__Do not__ Monitor and update containers that have `com.centurylinklabs.watchtower.enable` label set to false and 
 no `--label-enable` argument is passed. Note that only one or the other (targeting by enable label) can be 
 used at the same time to target containers.
 
@@ -238,6 +238,18 @@ Environment Variable: WATCHTOWER_MONITOR_ONLY
 
 Note that monitor-only can also be specified on a per-container basis with the `com.centurylinklabs.watchtower.monitor-only` label set on those containers.
 
+## With label taking precedence over environment variables
+
+By default, environement variables will take precedence over labels. This means that if you set `WATCHTOWER_MONITOR_ONLY` to true, a container with `com.centurylinklabs.watchtower.monitor-only` set to false will not be updated. If you set `WATCHTOWER_LABEL_TAKE_PRECEDENCE` to true, then the container will also be updated
+
+
+```text
+            Argument: --label-take-precedence
+Environment Variable: WATCHTOWER_LABEL_TAKE_PRECEDENCE
+                Type: Boolean
+             Default: false
+```
+
 ## Without restarting containers
 Do not restart containers after updating. This option can be useful when the start of the containers
 is managed by an external system such as systemd.

internal/actions/update.go

@@ -34,7 +34,7 @@ func Update(client container.Client, params types.UpdateParams) (types.Report, e
 
 	for i, targetContainer := range containers {
 		stale, newestImage, err := client.IsContainerStale(targetContainer)
-		shouldUpdate := stale && !params.NoRestart && !params.MonitorOnly && !targetContainer.IsMonitorOnly()
+		shouldUpdate := stale && !params.NoRestart && (( !params.MonitorOnly && !targetContainer.IsMonitorOnly() ) || ( params.LabelPrecedence && !targetContainer.IsMonitorOnly() ))
 		if err == nil && shouldUpdate {
 			// Check to make sure we have all the necessary information for recreating the container
 			err = targetContainer.VerifyConfiguration()
@@ -72,7 +72,7 @@ func Update(client container.Client, params types.UpdateParams) (types.Report, e
 	UpdateImplicitRestart(containers)
 
 	var containersToUpdate []types.Container
-	if !params.MonitorOnly {
+	if ( !params.MonitorOnly || params.LabelPrecedence ) {
 		for _, c := range containers {
 			if !c.IsMonitorOnly() {
 				containersToUpdate = append(containersToUpdate, c)

internal/actions/update_test.go

@@ -182,8 +182,41 @@ var _ = Describe("the update action", func() {
 				Expect(err).NotTo(HaveOccurred())
 				Expect(client.TestData.TriedToRemoveImageCount).To(Equal(0))
 			})
-		})
 
+			When("watchtower has been instructed to have label take precedence", func() {
+				It("it should update containers with monitor only set to false", func() {
+					client := CreateMockClient(
+						&TestData{
+							NameOfContainerToKeep: "test-container-02",
+							Containers: []types.Container{
+								CreateMockContainer(
+									"test-container-01",
+									"test-container-01",
+									"fake-image1:latest",
+									time.Now()),
+								CreateMockContainerWithConfig(
+									"test-container-02",
+									"test-container-02",
+									"fake-image2:latest",
+									false,
+									false,
+									time.Now(),
+									&dockerContainer.Config{
+										Labels: map[string]string{
+											"com.centurylinklabs.watchtower.monitor-only": "false",
+										},
+									}),
+							},
+						},
+						false,
+						false,
+					)
+					_, err := actions.Update(client, types.UpdateParams{MonitorOnly: true, LabelPrecedence: true})
+					Expect(err).To(HaveOccurred())
+					Expect(client.TestData.TriedToRemoveImageCount).To(Equal(1))
+				})
+			})
+		})
 	})
 
 	When("watchtower has been instructed to run lifecycle hooks", func() {

internal/flags/flags.go

@@ -185,6 +185,12 @@ func RegisterSystemFlags(rootCmd *cobra.Command) {
 		"log-level",
 		viper.GetString("WATCHTOWER_LOG_LEVEL"),
 		"The maximum log level that will be written to STDERR. Possible values: panic, fatal, error, warn, info, debug or trace")
+
+	flags.BoolP(
+		"label-take-precedence",
+		"",
+		viper.GetBool("WATCHTOWER_LABEL_TAKE_PRECEDENCE"),
+		"Label applied to containers take precedence over environement variable")
 }
 
 // RegisterNotificationFlags that are used by watchtower to send notifications

pkg/types/update_params.go

@@ -13,4 +13,5 @@ type UpdateParams struct {
 	MonitorOnly     bool
 	LifecycleHooks  bool
 	RollingRestart  bool
+	LabelPrecedence bool
 }