refactor: move actions into pkg

pkg/actions/check.go

@@ -0,0 +1,84 @@
+package actions
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/opencontainers/runc/Godeps/_workspace/src/github.com/Sirupsen/logrus"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/containrrr/watchtower/pkg/container"
+)
+
+// CheckForMultipleWatchtowerInstances will ensure that there are not multiple instances of the
+// watchtower running simultaneously. If multiple watchtower containers are detected, this function
+// will stop and remove all but the most recently started container.
+func CheckForMultipleWatchtowerInstances(client container.Client, cleanup bool) error {
+	awaitDockerClient()
+	containers, err := client.ListContainers(container.WatchtowerContainersFilter)
+
+	if err != nil {
+		log.Fatal(err)
+		return err
+	}
+
+	if len(containers) <= 1 {
+		log.Debug("There are no additional watchtower containers")
+		return nil
+	}
+
+	log.Info("Found multiple running watchtower instances. Cleaning up.")
+	return cleanupExcessWatchtowers(containers, client, cleanup)
+}
+
+func cleanupExcessWatchtowers(containers []container.Container, client container.Client, cleanup bool) error {
+	var cleanupErrors int
+	var stopErrors int
+
+	sort.Sort(container.ByCreated(containers))
+	allContainersExceptLast := containers[0 : len(containers)-1]
+
+	for _, c := range allContainersExceptLast {
+		if err := client.StopContainer(c, 60); err != nil {
+			// logging the original here as we're just returning a count
+			logrus.Error(err)
+			stopErrors++
+			continue
+		}
+
+		if cleanup == true {
+			if err := client.RemoveImage(c); err != nil {
+				// logging the original here as we're just returning a count
+				logrus.Error(err)
+				cleanupErrors++
+			}
+		}
+	}
+
+	return createErrorIfAnyHaveOccurred(stopErrors, cleanupErrors)
+}
+
+func createErrorIfAnyHaveOccurred(c int, i int) error {
+	if c == 0 && i == 0 {
+		return nil
+	}
+
+	var output strings.Builder
+
+	if c > 0 {
+		output.WriteString(fmt.Sprintf("%d errors while stopping containers", c))
+	}
+	if i > 0 {
+		output.WriteString(fmt.Sprintf("%d errors while cleaning up images", c))
+	}
+	return errors.New(output.String())
+}
+
+func awaitDockerClient() {
+	log.Debug("Sleeping for a seconds to ensure the docker api client has been properly initialized.")
+	time.Sleep(1 * time.Second)
+}