fix(lifecycle): cleanup lifecycle

- removes unwieldy SkipUpdate return value in favor of errors.Is
- generalizes the code for all four phases
- allows timeout to be defined for all phases
- enables explicit unit in timeout label values (in addition to implicit minutes)

pkg/container/metadata.go

@@ -1,43 +1,28 @@
 package container
 
-import "strconv"
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"time"
 
-const (
-	watchtowerLabel        = "com.centurylinklabs.watchtower"
-	signalLabel            = "com.centurylinklabs.watchtower.stop-signal"
-	enableLabel            = "com.centurylinklabs.watchtower.enable"
-	monitorOnlyLabel       = "com.centurylinklabs.watchtower.monitor-only"
-	noPullLabel            = "com.centurylinklabs.watchtower.no-pull"
-	dependsOnLabel         = "com.centurylinklabs.watchtower.depends-on"
-	zodiacLabel            = "com.centurylinklabs.zodiac.original-image"
-	scope                  = "com.centurylinklabs.watchtower.scope"
-	preCheckLabel          = "com.centurylinklabs.watchtower.lifecycle.pre-check"
-	postCheckLabel         = "com.centurylinklabs.watchtower.lifecycle.post-check"
-	preUpdateLabel         = "com.centurylinklabs.watchtower.lifecycle.pre-update"
-	postUpdateLabel        = "com.centurylinklabs.watchtower.lifecycle.post-update"
-	preUpdateTimeoutLabel  = "com.centurylinklabs.watchtower.lifecycle.pre-update-timeout"
-	postUpdateTimeoutLabel = "com.centurylinklabs.watchtower.lifecycle.post-update-timeout"
+	"github.com/containrrr/watchtower/internal/util"
+	wt "github.com/containrrr/watchtower/pkg/types"
+
+	"github.com/sirupsen/logrus"
 )
 
-// GetLifecyclePreCheckCommand returns the pre-check command set in the container metadata or an empty string
-func (c Container) GetLifecyclePreCheckCommand() string {
-	return c.getLabelValueOrEmpty(preCheckLabel)
-}
-
-// GetLifecyclePostCheckCommand returns the post-check command set in the container metadata or an empty string
-func (c Container) GetLifecyclePostCheckCommand() string {
-	return c.getLabelValueOrEmpty(postCheckLabel)
-}
-
-// GetLifecyclePreUpdateCommand returns the pre-update command set in the container metadata or an empty string
-func (c Container) GetLifecyclePreUpdateCommand() string {
-	return c.getLabelValueOrEmpty(preUpdateLabel)
-}
-
-// GetLifecyclePostUpdateCommand returns the post-update command set in the container metadata or an empty string
-func (c Container) GetLifecyclePostUpdateCommand() string {
-	return c.getLabelValueOrEmpty(postUpdateLabel)
-}
+const (
+	namespace        = "com.centurylinklabs.watchtower"
+	watchtowerLabel  = namespace
+	signalLabel      = namespace + ".stop-signal"
+	enableLabel      = namespace + ".enable"
+	monitorOnlyLabel = namespace + ".monitor-only"
+	noPullLabel      = namespace + ".no-pull"
+	dependsOnLabel   = namespace + ".depends-on"
+	zodiacLabel      = "com.centurylinklabs.zodiac.original-image"
+	scope            = namespace + ".scope"
+)
 
 // ContainsWatchtowerLabel takes a map of labels and values and tells
 // the consumer whether it contains a valid watchtower instance label
@@ -46,22 +31,62 @@ func ContainsWatchtowerLabel(labels map[string]string) bool {
 	return ok && val == "true"
 }
 
-func (c Container) getLabelValueOrEmpty(label string) string {
+// GetLifecycleCommand returns the lifecycle command set in the container metadata or an empty string
+func (c *Container) GetLifecycleCommand(phase wt.LifecyclePhase) string {
+	label := fmt.Sprintf("%v.lifecycle.%v", namespace, phase)
+	value, found := c.getLabelValue(label)
+
+	if !found {
+		return ""
+	}
+
+	return value
+}
+
+// GetLifecycleTimeout checks whether a container has a specific timeout set
+// for how long the lifecycle command is allowed to run. This value is expressed
+// either as a duration, an integer (minutes implied), or as 0 which will allow the command/script
+// to run indefinitely. Users should be cautious with the 0 option, as that
+// could result in watchtower waiting forever.
+func (c *Container) GetLifecycleTimeout(phase wt.LifecyclePhase) time.Duration {
+	label := fmt.Sprintf("%v.lifecycle.%v-timeout", namespace, phase)
+	timeout, err := c.getDurationLabelValue(label, time.Minute)
+
+	if err != nil {
+		timeout = time.Minute
+		if !errors.Is(err, errorLabelNotFound) {
+			logrus.WithError(err).Errorf("could not parse timeout label value for %v lifecycle", phase)
+		}
+	}
+
+	return timeout
+}
+
+func (c *Container) getLabelValueOrEmpty(label string) string {
 	if val, ok := c.containerInfo.Config.Labels[label]; ok {
 		return val
 	}
 	return ""
 }
 
-func (c Container) getLabelValue(label string) (string, bool) {
+func (c *Container) getLabelValue(label string) (string, bool) {
 	val, ok := c.containerInfo.Config.Labels[label]
 	return val, ok
 }
 
-func (c Container) getBoolLabelValue(label string) (bool, error) {
+func (c *Container) getBoolLabelValue(label string) (bool, error) {
 	if strVal, ok := c.containerInfo.Config.Labels[label]; ok {
 		value, err := strconv.ParseBool(strVal)
 		return value, err
 	}
 	return false, errorLabelNotFound
 }
+
+func (c *Container) getDurationLabelValue(label string, unitlessUnit time.Duration) (time.Duration, error) {
+	value, found := c.getLabelValue(label)
+	if !found || len(value) < 1 {
+		return 0, errorLabelNotFound
+	}
+
+	return util.ParseDuration(value, unitlessUnit)
+}