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Change-Id: Ie4c20d06b360d9659ee0477b13c79dc6a86f3e85 Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
64 lines
2.1 KiB
Go
64 lines
2.1 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package services manages graceful shutdown of Tailscale Services advertised
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// by Kubernetes clients.
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package services
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import (
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"context"
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"fmt"
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"time"
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"tailscale.com/client/local"
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"tailscale.com/ipn"
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"tailscale.com/types/logger"
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)
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// EnsureServicesNotAdvertised is a function that gets called on containerboot
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// or k8s-proxy termination and ensures that any currently advertised Services
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// get unadvertised to give clients time to switch to another node before this
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// one is shut down.
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func EnsureServicesNotAdvertised(ctx context.Context, lc *local.Client, logf logger.Logf) error {
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prefs, err := lc.GetPrefs(ctx)
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if err != nil {
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return fmt.Errorf("error getting prefs: %w", err)
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}
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if len(prefs.AdvertiseServices) == 0 {
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return nil
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}
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logf("unadvertising services: %v", prefs.AdvertiseServices)
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if _, err := lc.EditPrefs(ctx, &ipn.MaskedPrefs{
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AdvertiseServicesSet: true,
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Prefs: ipn.Prefs{
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AdvertiseServices: nil,
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},
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}); err != nil {
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// EditPrefs only returns an error if it fails _set_ its local prefs.
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// If it fails to _persist_ the prefs in state, we don't get an error
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// and we continue waiting below, as control will failover as usual.
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return fmt.Errorf("error setting prefs AdvertiseServices: %w", err)
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}
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// Services use the same (failover XOR regional routing) mechanism that
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// HA subnet routers use. Unfortunately we don't yet get a reliable signal
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// from control that it's responded to our unadvertisement, so the best we
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// can do is wait for 20 seconds, where 15s is the approximate maximum time
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// it should take for control to choose a new primary, and 5s is for buffer.
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//
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// Note: There is no guarantee that clients have been _informed_ of the new
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// primary no matter how long we wait. We would need a mechanism to await
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// netmap updates for peers to know for sure.
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//
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// See https://tailscale.com/kb/1115/high-availability for more details.
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// TODO(tomhjp): Wait for a netmap update instead of sleeping when control
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// supports that.
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select {
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case <-ctx.Done():
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return nil
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case <-time.After(2 * time.Second):
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return nil
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}
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}
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