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https://github.com/siderolabs/talos.git
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c4fb7dad0e
I observed a random failure (via Sidero Metal integration tests) when Talos fails to reboot due to the runner never shutting down. A probable root cause is a bug in the `dns` library (which runs the NDS server), but we need to ensure this code always terminates, even at the price of leaking a running DNS server. Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
106 lines
2.4 KiB
Go
106 lines
2.4 KiB
Go
// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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package dns
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import (
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"context"
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"errors"
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"io"
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"net"
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"time"
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"github.com/miekg/dns"
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"go.uber.org/zap"
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)
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// RunnerOptions is a [Runner] options.
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type RunnerOptions struct {
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Listener net.Listener
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PacketConn net.PacketConn
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Handler dns.Handler
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ReadTimeout time.Duration
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WriteTimeout time.Duration
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IdleTimeout func() time.Duration
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MaxTCPQueries int
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}
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// NewRunner creates a new [Runner].
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func NewRunner(opts RunnerOptions, l *zap.Logger) *Runner {
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return &Runner{
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srv: &dns.Server{
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Listener: opts.Listener,
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PacketConn: opts.PacketConn,
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Handler: opts.Handler,
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UDPSize: dns.DefaultMsgSize, // 4096 since default is [dns.MinMsgSize] = 512 bytes, which is too small.
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ReadTimeout: opts.ReadTimeout,
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WriteTimeout: opts.WriteTimeout,
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IdleTimeout: opts.IdleTimeout,
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MaxTCPQueries: opts.MaxTCPQueries,
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},
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logger: l,
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}
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}
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// Runner is a DNS server runner.
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type Runner struct {
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srv *dns.Server
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logger *zap.Logger
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}
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// Serve starts the DNS server. Implements [suture.Service] interface.
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func (r *Runner) Serve(ctx context.Context) error {
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errCh := make(chan error)
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go func() {
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errCh <- r.srv.ActivateAndServe()
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}()
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select {
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case err := <-errCh:
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return err
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case <-ctx.Done():
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}
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r.close()
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select {
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case err := <-errCh:
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return err
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case <-time.After(time.Second):
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return errors.New("timeout waiting for server to close")
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}
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}
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func (r *Runner) close() {
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l := r.logger
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if r.srv.Listener != nil {
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l = l.With(zap.String("net", "tcp"), zap.String("local_addr", r.srv.Listener.Addr().String()))
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} else if r.srv.PacketConn != nil {
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l = l.With(zap.String("net", "udp"), zap.String("local_addr", r.srv.PacketConn.LocalAddr().String()))
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}
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closer := io.Closer(r.srv.Listener)
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if closer == nil {
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closer = r.srv.PacketConn
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}
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if closer != nil {
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if err := closer.Close(); err != nil {
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l.Error("error closing dns server listener", zap.Error(err))
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} else {
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l.Debug("dns server listener closed")
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}
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}
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sCtx, sCancel := context.WithTimeout(context.Background(), 5*time.Second)
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defer sCancel()
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err := r.srv.ShutdownContext(sCtx)
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if err != nil && !errors.Is(err, net.ErrClosed) {
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l.Error("error shutting down dns server", zap.Error(err))
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}
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}
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