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watchtower/container/container.go

198 lines
5.8 KiB
Go

package container
import (
"fmt"
"strconv"
"strings"
"github.com/docker/docker/api/types"
dockercontainer "github.com/docker/docker/api/types/container"
)
const (
watchtowerLabel = "com.centurylinklabs.watchtower"
signalLabel = "com.centurylinklabs.watchtower.stop-signal"
enableLabel = "com.centurylinklabs.watchtower.enable"
zodiacLabel = "com.centurylinklabs.zodiac.original-image"
)
// NewContainer returns a new Container instance instantiated with the
// specified ContainerInfo and ImageInfo structs.
func NewContainer(containerInfo *types.ContainerJSON, imageInfo *types.ImageInspect) *Container {
return &Container{
containerInfo: containerInfo,
imageInfo: imageInfo,
}
}
// Container represents a running Docker container.
type Container struct {
Stale bool
containerInfo *types.ContainerJSON
imageInfo *types.ImageInspect
}
// ID returns the Docker container ID.
func (c Container) ID() string {
return c.containerInfo.ID
}
// IsRunning returns a boolean flag indicating whether or not the current
// container is running. The status is determined by the value of the
// container's "State.Running" property.
func (c Container) IsRunning() bool {
return c.containerInfo.State.Running
}
// Name returns the Docker container name.
func (c Container) Name() string {
return c.containerInfo.Name
}
// ImageID returns the ID of the Docker image that was used to start the
// container.
func (c Container) ImageID() string {
return c.imageInfo.ID
}
// ImageName returns the name of the Docker image that was used to start the
// container. If the original image was specified without a particular tag, the
// "latest" tag is assumed.
func (c Container) ImageName() string {
// Compatibility w/ Zodiac deployments
imageName, ok := c.containerInfo.Config.Labels[zodiacLabel]
if !ok {
imageName = c.containerInfo.Config.Image
}
if !strings.Contains(imageName, ":") {
imageName = fmt.Sprintf("%s:latest", imageName)
}
return imageName
}
// Enabled returns the value of the container enabled label and if the label
// was set.
func (c Container) Enabled() (bool, bool) {
rawBool, ok := c.containerInfo.Config.Labels[enableLabel]
if !ok {
return false, false
}
parsedBool, err := strconv.ParseBool(rawBool)
if err != nil {
return false, false
}
return parsedBool, true
}
// Links returns a list containing the names of all the containers to which
// this container is linked.
func (c Container) Links() []string {
var links []string
if (c.containerInfo != nil) && (c.containerInfo.HostConfig != nil) {
for _, link := range c.containerInfo.HostConfig.Links {
name := strings.Split(link, ":")[0]
links = append(links, name)
}
}
return links
}
// IsWatchtower returns a boolean flag indicating whether or not the current
// container is the watchtower container itself. The watchtower container is
// identified by the presence of the "com.centurylinklabs.watchtower" label in
// the container metadata.
func (c Container) IsWatchtower() bool {
return ContainsWatchtowerLabel(c.containerInfo.Config.Labels)
}
// StopSignal returns the custom stop signal (if any) that is encoded in the
// container's metadata. If the container has not specified a custom stop
// signal, the empty string "" is returned.
func (c Container) StopSignal() string {
if val, ok := c.containerInfo.Config.Labels[signalLabel]; ok {
return val
}
return ""
}
// Ideally, we'd just be able to take the ContainerConfig from the old container
// and use it as the starting point for creating the new container; however,
// the ContainerConfig that comes back from the Inspect call merges the default
// configuration (the stuff specified in the metadata for the image itself)
// with the overridden configuration (the stuff that you might specify as part
// of the "docker run"). In order to avoid unintentionally overriding the
// defaults in the new image we need to separate the override options from the
// default options. To do this we have to compare the ContainerConfig for the
// running container with the ContainerConfig from the image that container was
// started from. This function returns a ContainerConfig which contains just
// the options overridden at runtime.
func (c Container) runtimeConfig() *dockercontainer.Config {
config := c.containerInfo.Config
imageConfig := c.imageInfo.Config
if config.WorkingDir == imageConfig.WorkingDir {
config.WorkingDir = ""
}
if config.User == imageConfig.User {
config.User = ""
}
if sliceEqual(config.Cmd, imageConfig.Cmd) {
config.Cmd = nil
}
if sliceEqual(config.Entrypoint, imageConfig.Entrypoint) {
config.Entrypoint = nil
}
config.Env = sliceSubtract(config.Env, imageConfig.Env)
config.Labels = stringMapSubtract(config.Labels, imageConfig.Labels)
config.Volumes = structMapSubtract(config.Volumes, imageConfig.Volumes)
// subtract ports exposed in image from container
for k := range config.ExposedPorts {
if _, ok := imageConfig.ExposedPorts[k]; ok {
delete(config.ExposedPorts, k)
}
}
for p := range c.containerInfo.HostConfig.PortBindings {
config.ExposedPorts[p] = struct{}{}
}
config.Image = c.ImageName()
return config
}
// Any links in the HostConfig need to be re-written before they can be
// re-submitted to the Docker create API.
func (c Container) hostConfig() *dockercontainer.HostConfig {
hostConfig := c.containerInfo.HostConfig
for i, link := range hostConfig.Links {
name := link[0:strings.Index(link, ":")]
alias := link[strings.LastIndex(link, "/"):]
hostConfig.Links[i] = fmt.Sprintf("%s:%s", name, alias)
}
return hostConfig
}
// ContainsWatchtowerLabel takes a map of labels and values and tells
// the consumer whether it contains a valid watchtower instance label
func ContainsWatchtowerLabel(labels map[string]string) bool {
val, ok := labels[watchtowerLabel]
return ok && val == "true"
}