fix: empty out the aliases on recreation (#1699)

* fix: empty out the aliases on recreation

* test alias purging

Author: simskij

pkg/container/client.go

@@ -208,11 +208,25 @@ func (client dockerClient) StopContainer(c t.Container, timeout time.Duration) e
 	return nil
 }
 
+func (client dockerClient) GetNetworkConfig(c t.Container) *network.NetworkingConfig {
+	config := &network.NetworkingConfig{
+		EndpointsConfig: c.ContainerInfo().NetworkSettings.Networks,
+	}
+
+	for _, ep := range config.EndpointsConfig {
+		// This keeps accumulating across upgrades with no apparent added value
+		// so throwing the information away to prevent overflows.
+		ep.Aliases = nil
+	}
+	return config
+}
+
 func (client dockerClient) StartContainer(c t.Container) (t.ContainerID, error) {
 	bg := context.Background()
 	config := c.GetCreateConfig()
 	hostConfig := c.GetCreateHostConfig()
-	networkConfig := &network.NetworkingConfig{EndpointsConfig: c.ContainerInfo().NetworkSettings.Networks}
+	networkConfig := client.GetNetworkConfig(c)
+
 	// simpleNetworkConfig is a networkConfig with only 1 network.
 	// see: https://github.com/docker/docker/issues/29265
 	simpleNetworkConfig := func() *network.NetworkingConfig {
@@ -228,6 +242,7 @@ func (client dockerClient) StartContainer(c t.Container) (t.ContainerID, error)
 	name := c.Name()
 
 	log.Infof("Creating %s", name)
+
 	createdContainer, err := client.api.ContainerCreate(bg, config, hostConfig, simpleNetworkConfig, nil, name)
 	if err != nil {
 		return "", err

pkg/container/client_test.go

@@ -1,6 +1,7 @@
 package container
 
 import (
+	"github.com/docker/docker/api/types/network"
 	"time"
 
 	"github.com/containrrr/watchtower/internal/util"
@@ -284,6 +285,24 @@ var _ = Describe("the client", func() {
 			})
 		})
 	})
+	Describe(`GetNetworkConfig`, func() {
+		When(`providing a container with network aliases`, func() {
+			It(`should purge the aliases`, func() {
+				aliases := []string{"One", "Two"}
+				client := dockerClient{
+					api:           docker,
+					ClientOptions: ClientOptions{PullImages: false, IncludeRestarting: false},
+				}
+				container := MockContainer(WithImageName("docker.io/prefix/imagename:latest"))
+				endpoints := map[string]*network.EndpointSettings{
+					`test`: {Aliases: aliases},
+				}
+				container.containerInfo.NetworkSettings = &types.NetworkSettings{Networks: endpoints}
+				Expect(container.ContainerInfo().NetworkSettings.Networks[`test`].Aliases).To(Equal(aliases))
+				Expect(client.GetNetworkConfig(container).EndpointsConfig[`test`].Aliases).To(BeEmpty())
+			})
+		})
+	})
 })
 
 // Capture logrus output in buffer