refactor: extract code from the container package

pkg/filters/filters.go

@@ -0,0 +1,65 @@
+package filters
+
+import t "github.com/containrrr/watchtower/pkg/types"
+
+// WatchtowerContainersFilter filters only watchtower containers
+func WatchtowerContainersFilter(c t.FilterableContainer) bool { return c.IsWatchtower() }
+
+// NoFilter will not filter out any containers
+func NoFilter(t.FilterableContainer) bool { return true }
+
+// FilterByNames returns all containers that match the specified name
+func FilterByNames(names []string, baseFilter t.Filter) t.Filter {
+	if len(names) == 0 {
+		return baseFilter
+	}
+
+	return func(c t.FilterableContainer) bool {
+		for _, name := range names {
+			if (name == c.Name()) || (name == c.Name()[1:]) {
+				return baseFilter(c)
+			}
+		}
+		return false
+	}
+}
+
+// FilterByEnableLabel returns all containers that have the enabled label set
+func FilterByEnableLabel(baseFilter t.Filter) t.Filter {
+	return func(c t.FilterableContainer) bool {
+		// If label filtering is enabled, containers should only be considered
+		// if the label is specifically set.
+		_, ok := c.Enabled()
+		if !ok {
+			return false
+		}
+
+		return baseFilter(c)
+	}
+}
+
+// FilterByDisabledLabel returns all containers that have the enabled label set to disable
+func FilterByDisabledLabel(baseFilter t.Filter) t.Filter {
+	return func(c t.FilterableContainer) bool {
+		enabledLabel, ok := c.Enabled()
+		if ok && !enabledLabel {
+			// If the label has been set and it demands a disable
+			return false
+		}
+
+		return baseFilter(c)
+	}
+}
+
+// BuildFilter creates the needed filter of containers
+func BuildFilter(names []string, enableLabel bool) t.Filter {
+	filter := NoFilter
+	filter = FilterByNames(names, filter)
+	if enableLabel {
+		// If label filtering is enabled, containers should only be considered
+		// if the label is specifically set.
+		filter = FilterByEnableLabel(filter)
+	}
+	filter = FilterByDisabledLabel(filter)
+	return filter
+}