// updateSupportedContainers records in state that a machine can run the specified containers.
// It starts a watcher and when a container of a given type is first added to the machine,
// the watcher is killed, the machine is set up to be able to start containers of the given type,
// and a suitable provisioner is started.
func (a *MachineAgent) updateSupportedContainers(
runner worker.Runner,
st api.Connection,
containers []instance.ContainerType,
agentConfig agent.Config,
) error {
pr := st.Provisioner()
tag := agentConfig.Tag().(names.MachineTag)
machine, err := pr.Machine(tag)
if errors.IsNotFound(err) || err == nil && machine.Life() == params.Dead {
return worker.ErrTerminateAgent
}
if err != nil {
return errors.Annotatef(err, "cannot load machine %s from state", tag)
}
if len(containers) == 0 {
if err := machine.SupportsNoContainers(); err != nil {
return errors.Annotatef(err, "clearing supported containers for %s", tag)
}
return nil
}
if err := machine.SetSupportedContainers(containers...); err != nil {
return errors.Annotatef(err, "setting supported containers for %s", tag)
}
initLock, err := cmdutil.HookExecutionLock(agentConfig.DataDir())
if err != nil {
return err
}
// Start the watcher to fire when a container is first requested on the machine.
modelUUID, err := st.ModelTag()
if err != nil {
return err
}
watcherName := fmt.Sprintf("%s-container-watcher", machine.Id())
// There may not be a CA certificate private key available, and without
// it we can't ensure that other Juju nodes can connect securely, so only
// use an image URL getter if there's a private key.
var imageURLGetter container.ImageURLGetter
if agentConfig.Value(agent.AllowsSecureConnection) == "true" {
cfg, err := pr.ModelConfig()
if err != nil {
return errors.Annotate(err, "unable to get environ config")
}
imageURLGetter = container.NewImageURLGetter(
// Explicitly call the non-named constructor so if anyone
// adds additional fields, this fails.
container.ImageURLGetterConfig{
ServerRoot: st.Addr(),
ModelUUID: modelUUID.Id(),
CACert: []byte(agentConfig.CACert()),
CloudimgBaseUrl: cfg.CloudImageBaseURL(),
Stream: cfg.ImageStream(),
ImageDownloadFunc: container.ImageDownloadURL,
})
}
params := provisioner.ContainerSetupParams{
Runner: runner,
WorkerName: watcherName,
SupportedContainers: containers,
ImageURLGetter: imageURLGetter,
Machine: machine,
Provisioner: pr,
Config: agentConfig,
InitLock: initLock,
}
handler := provisioner.NewContainerSetupHandler(params)
a.startWorkerAfterUpgrade(runner, watcherName, func() (worker.Worker, error) {
w, err := watcher.NewStringsWorker(watcher.StringsConfig{
Handler: handler,
})
if err != nil {
return nil, errors.Annotatef(err, "cannot start %s worker", watcherName)
}
return w, nil
})
return nil
}