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Add faster availability DNS probe and update test domain to .com #2280

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merged 3 commits into from
Jul 17, 2024
Merged

Add faster availability DNS probe and update test domain to .com #2280

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338cb8d
Add faster availability DNS probe and update test domain to .com
mlsmaycon Jul 16, 2024
ab85711
use fqdn
mlsmaycon Jul 16, 2024
428a204
Update client/internal/dns/upstream.go
mlsmaycon Jul 17, 2024
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19 changes: 14 additions & 5 deletions client/internal/dns/upstream.go
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ const (
probeTimeout = 2 * time.Second
)

const testRecord = "."
const testRecord = "com."

type upstreamClient interface {
exchange(ctx context.Context, upstream string, r *dns.Msg) (*dns.Msg, time.Duration, error)
Expand All @@ -42,6 +42,7 @@ type upstreamResolverBase struct {
upstreamServers []string
disabled bool
failsCount atomic.Int32
successCount atomic.Int32
failsTillDeact int32
mutex sync.Mutex
reactivatePeriod time.Duration
Expand Down Expand Up @@ -124,6 +125,7 @@ func (u *upstreamResolverBase) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
return
}

u.successCount.Add(1)
log.Tracef("took %s to query the upstream %s", t, upstream)

err = w.WriteMsg(rm)
Expand Down Expand Up @@ -172,6 +174,11 @@ func (u *upstreamResolverBase) probeAvailability() {
default:
}

// avoid probe if upstreams could resolve at least one query and fails count is less than failsTillDeact
if u.successCount.Load() > 0 && u.failsCount.Load() < u.failsTillDeact {
return
}

var success bool
var mu sync.Mutex
var wg sync.WaitGroup
Expand All @@ -183,7 +190,7 @@ func (u *upstreamResolverBase) probeAvailability() {
wg.Add(1)
go func() {
defer wg.Done()
err := u.testNameserver(upstream)
err := u.testNameserver(upstream, 500*time.Millisecond)
if err != nil {
errors = multierror.Append(errors, err)
log.Warnf("probing upstream nameserver %s: %s", upstream, err)
Expand Down Expand Up @@ -224,7 +231,7 @@ func (u *upstreamResolverBase) waitUntilResponse() {
}

for _, upstream := range u.upstreamServers {
if err := u.testNameserver(upstream); err != nil {
if err := u.testNameserver(upstream, probeTimeout); err != nil {
log.Tracef("upstream check for %s: %s", upstream, err)
} else {
// at least one upstream server is available, stop probing
Expand All @@ -244,6 +251,7 @@ func (u *upstreamResolverBase) waitUntilResponse() {

log.Infof("upstreams %s are responsive again. Adding them back to system", u.upstreamServers)
u.failsCount.Store(0)
u.successCount.Add(1)
u.reactivate()
u.disabled = false
}
Expand All @@ -265,13 +273,14 @@ func (u *upstreamResolverBase) disable(err error) {
}

log.Warnf("Upstream resolving is Disabled for %v", reactivatePeriod)
u.successCount.Store(0)
u.deactivate(err)
u.disabled = true
go u.waitUntilResponse()
}

func (u *upstreamResolverBase) testNameserver(server string) error {
ctx, cancel := context.WithTimeout(u.ctx, probeTimeout)
func (u *upstreamResolverBase) testNameserver(server string, timeout time.Duration) error {
ctx, cancel := context.WithTimeout(u.ctx, timeout)
defer cancel()

r := new(dns.Msg).SetQuestion(testRecord, dns.TypeSOA)
Expand Down
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