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watchtower/actions/update.go

116 lines
2.7 KiB
Go

package actions
import (
"math/rand"
"time"
"github.com/containrrr/watchtower/container"
log "github.com/sirupsen/logrus"
)
var (
letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
)
// Update looks at the running Docker containers to see if any of the images
// used to start those containers have been updated. If a change is detected in
// any of the images, the associated containers are stopped and restarted with
// the new image.
func Update(client container.Client, filter container.Filter, cleanup bool, noRestart bool, timeout time.Duration) error {
log.Debug("Checking containers for updated images")
containers, err := client.ListContainers(filter)
if err != nil {
return err
}
for i, container := range containers {
stale, err := client.IsContainerStale(container)
if err != nil {
log.Infof("Unable to update container %s, err='%s'. Proceeding to next.", containers[i].Name(), err)
stale = false
}
containers[i].Stale = stale
}
containers, err = container.SortByDependencies(containers)
if err != nil {
return err
}
checkDependencies(containers)
// Stop stale containers in reverse order
for i := len(containers) - 1; i >= 0; i-- {
container := containers[i]
if container.IsWatchtower() {
log.Debugf("This is the watchtower container %s", containers[i].Name())
continue
}
if container.Stale {
if err := client.StopContainer(container, timeout); err != nil {
log.Error(err)
}
}
}
// Restart stale containers in sorted order
for _, container := range containers {
if container.Stale {
// Since we can't shutdown a watchtower container immediately, we need to
// start the new one while the old one is still running. This prevents us
// from re-using the same container name so we first rename the current
// instance so that the new one can adopt the old name.
if container.IsWatchtower() {
if err := client.RenameContainer(container, randName()); err != nil {
log.Error(err)
continue
}
}
if !noRestart {
if err := client.StartContainer(container); err != nil {
log.Error(err)
}
}
if cleanup {
client.RemoveImage(container)
}
}
}
return nil
}
func checkDependencies(containers []container.Container) {
for i, parent := range containers {
if parent.Stale {
continue
}
LinkLoop:
for _, linkName := range parent.Links() {
for _, child := range containers {
if child.Name() == linkName && child.Stale {
containers[i].Stale = true
break LinkLoop
}
}
}
}
}
// Generates a random, 32-character, Docker-compatible container name.
func randName() string {
b := make([]rune, 32)
for i := range b {
b[i] = letters[rand.Intn(len(letters))]
}
return string(b)
}