tailscale/kube/services/services.go
Tom Proctor 2914e31812 debug
Change-Id: Ie4c20d06b360d9659ee0477b13c79dc6a86f3e85
Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
2025-07-25 13:55:25 +01:00

64 lines
2.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package services manages graceful shutdown of Tailscale Services advertised
// by Kubernetes clients.
package services
import (
"context"
"fmt"
"time"
"tailscale.com/client/local"
"tailscale.com/ipn"
"tailscale.com/types/logger"
)
// EnsureServicesNotAdvertised is a function that gets called on containerboot
// or k8s-proxy termination and ensures that any currently advertised Services
// get unadvertised to give clients time to switch to another node before this
// one is shut down.
func EnsureServicesNotAdvertised(ctx context.Context, lc *local.Client, logf logger.Logf) error {
prefs, err := lc.GetPrefs(ctx)
if err != nil {
return fmt.Errorf("error getting prefs: %w", err)
}
if len(prefs.AdvertiseServices) == 0 {
return nil
}
logf("unadvertising services: %v", prefs.AdvertiseServices)
if _, err := lc.EditPrefs(ctx, &ipn.MaskedPrefs{
AdvertiseServicesSet: true,
Prefs: ipn.Prefs{
AdvertiseServices: nil,
},
}); err != nil {
// EditPrefs only returns an error if it fails _set_ its local prefs.
// If it fails to _persist_ the prefs in state, we don't get an error
// and we continue waiting below, as control will failover as usual.
return fmt.Errorf("error setting prefs AdvertiseServices: %w", err)
}
// Services use the same (failover XOR regional routing) mechanism that
// HA subnet routers use. Unfortunately we don't yet get a reliable signal
// from control that it's responded to our unadvertisement, so the best we
// can do is wait for 20 seconds, where 15s is the approximate maximum time
// it should take for control to choose a new primary, and 5s is for buffer.
//
// Note: There is no guarantee that clients have been _informed_ of the new
// primary no matter how long we wait. We would need a mechanism to await
// netmap updates for peers to know for sure.
//
// See https://tailscale.com/kb/1115/high-availability for more details.
// TODO(tomhjp): Wait for a netmap update instead of sleeping when control
// supports that.
select {
case <-ctx.Done():
return nil
case <-time.After(2 * time.Second):
return nil
}
}