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Print DNS errors #1607

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merged 2 commits into from
Jun 27, 2016
Merged

Print DNS errors #1607

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Print DNS errors
Jun 23, 2016
d33358e
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Jun 27, 2016
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26 changes: 17 additions & 9 deletions probe/appclient/resolver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -49,10 +49,11 @@ type Resolver interface {
}

type staticResolver struct {
setters []setter
targets []target
quit chan struct{}
lookup LookupIP
setters []setter
targets []target
failedResolutions map[string]struct{}
quit chan struct{}
lookup LookupIP
}

// LookupIP type is used for looking up IPs.
Expand All @@ -67,10 +68,11 @@ func (t target) String() string { return net.JoinHostPort(t.host, t.port) }
// resolve to multiple IPs. It uses the supplied DNS server name.
func NewResolver(targets []string, lookup LookupIP, setters ...setter) Resolver {
r := staticResolver{
targets: prepare(targets),
setters: setters,
quit: make(chan struct{}),
lookup: lookup,
targets: prepare(targets),
setters: setters,
failedResolutions: map[string]struct{}{},
quit: make(chan struct{}),
lookup: lookup,
}
go r.loop()
return r
Expand Down Expand Up @@ -158,9 +160,15 @@ func (r staticResolver) resolveOne(t target) []string {
var err error
addrs, err = r.lookup(t.host)
if err != nil {
log.Debugf("Error resolving %s: %v", t.host, err)
if _, ok := r.failedResolutions[t.host]; !ok {
log.Warnf("Cannot resolve %s: %v", t.host, err)
// Only log the error once
r.failedResolutions[t.host] = struct{}{}
}
return []string{}
}
// Allow logging errors in future resolutions
delete(r.failedResolutions, t.host)
}
endpoints := make([]string, 0, len(addrs))
for _, addr := range addrs {
Expand Down