Adding new runtime param delay-days that is used to control whether container is updated to new image immediately or wait until the indicated days have passed

cmd/root.go

@@ -39,6 +39,7 @@ var (
 	disableContainers []string
 	notifier          t.Notifier
 	timeout           time.Duration
+	delayDays         int
 	lifecycleHooks    bool
 	rollingRestart    bool
 	scope             string
@@ -96,6 +97,7 @@ func PreRun(cmd *cobra.Command, _ []string) {
 
 	enableLabel, _ = f.GetBool("label-enable")
 	disableContainers, _ = f.GetStringSlice("disable-containers")
+	delayDays, _ = f.GetInt("delay-days")
 	lifecycleHooks, _ = f.GetBool("enable-lifecycle-hooks")
 	rollingRestart, _ = f.GetBool("rolling-restart")
 	scope, _ = f.GetString("scope")
@@ -364,6 +366,7 @@ func runUpdatesWithNotifications(filter t.Filter) *metrics.Metric {
 		NoRestart:       noRestart,
 		Timeout:         timeout,
 		MonitorOnly:     monitorOnly,
+		DelayDays:       delayDays,
 		LifecycleHooks:  lifecycleHooks,
 		RollingRestart:  rollingRestart,
 		LabelPrecedence: labelPrecedence,

docs/arguments.md

@@ -381,6 +381,16 @@ Environment Variable: WATCHTOWER_HTTP_API_METRICS
              Default: false
 ```
 
+## Delayed Update
+Only update container to latest version of image if some number of days have passed since it has been published. This option may be useful for those who wish to avoid updating prior to the new version having some time in the field prior to updating in case there are critical defects found and released in a subsequent version.
+
+```text
+            Argument: --delay-days
+Environment Variable: WATCHTOWER_DELAY_DAYS
+                Type: Integer
+             Default: false
+```
+
 ## Scheduling
 [Cron expression](https://pkg.go.dev/github.com/robfig/cron@v1.2.0?tab=doc#hdr-CRON_Expression_Format) in 6 fields (rather than the traditional 5) which defines when and how often to check for new images. Either `--interval` or the schedule expression
 can be defined, but not both. An example: `--schedule "0 0 4 * * *"`

internal/flags/flags.go

@@ -147,6 +147,12 @@ func RegisterSystemFlags(rootCmd *cobra.Command) {
 		envBool("WATCHTOWER_LIFECYCLE_HOOKS"),
 		"Enable the execution of commands triggered by pre- and post-update lifecycle hooks")
 
+	flags.IntP(
+		"delay-days",
+		"0",
+		envInt("WATCHTOWER_DELAY_DAYS"),
+		"Number of days to wait for new image version to be in place prior to installing it")
+
 	flags.BoolP(
 		"rolling-restart",
 		"",

pkg/container/client.go

@@ -325,10 +325,25 @@ func (client dockerClient) IsContainerStale(container t.Container, params t.Upda
 		return false, container.SafeImageID(), err
 	}
 
-	return client.HasNewImage(ctx, container)
+	return client.HasNewImage(ctx, container, params)
 }
 
-func (client dockerClient) HasNewImage(ctx context.Context, container t.Container) (hasNew bool, latestImage t.ImageID, err error) {
+// Date strings sometimes vary in how many digits after the decimal point are present. This function
+// standardizes them by removing the milliseconds.
+func truncateMilliseconds(dateString string) string {
+	// Find the position of the dot (.) in the date string
+	dotIndex := strings.Index(dateString, ".")
+
+	// If the dot is found, truncate the string before the dot
+	if dotIndex != -1 {
+		return dateString[:dotIndex] + "Z"
+	}
+
+	// If the dot is not found, return the original string
+	return dateString
+}
+
+func (client dockerClient) HasNewImage(ctx context.Context, container t.Container, params t.UpdateParams) (hasNew bool, latestImage t.ImageID, err error) {
 	currentImageID := t.ImageID(container.ContainerInfo().ContainerJSONBase.Image)
 	imageName := container.ImageName()
 
@@ -339,10 +354,30 @@ func (client dockerClient) HasNewImage(ctx context.Context, container t.Containe
 
 	newImageID := t.ImageID(newImageInfo.ID)
 	if newImageID == currentImageID {
-		log.Debugf("No new images found for %s", container.Name())
+		log.Debugf("No new images found for %s [ imageID %s ]", container.Name(), newImageID.ShortID())
 		return false, currentImageID, nil
 	}
 
+	// Disabled by default
+	if params.DelayDays > 0 {
+		// Define the layout string for the date format without milliseconds
+		layout := "2006-01-02T15:04:05Z"
+		newImageDate, error := time.Parse(layout, truncateMilliseconds(newImageInfo.Created))
+
+		if error != nil {
+			log.Errorf("Error parsing Created date (%s) for container %s latest label. Error: %s", newImageInfo.Created, container.Name(), error)
+			return false, currentImageID, nil
+		} else {
+			requiredDays := params.DelayDays
+			diffDays := int(time.Since(newImageDate).Hours() / 24)
+
+			if diffDays < requiredDays {
+				log.Infof("New image found for %s that is %d days since publication but update delayed until %d days", container.Name(), diffDays, requiredDays)
+				return false, currentImageID, nil
+			}
+		}
+	}
+
 	log.Infof("Found new %s image (%s)", imageName, newImageID.ShortID())
 	return true, newImageID, nil
 }

pkg/types/update_params.go

@@ -11,7 +11,8 @@ type UpdateParams struct {
 	NoRestart       bool
 	Timeout         time.Duration
 	MonitorOnly     bool
-	NoPull			bool
+	NoPull          bool
+	DelayDays       int
 	LifecycleHooks  bool
 	RollingRestart  bool
 	LabelPrecedence bool