add dns caching #64
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add dns caching #64
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aojea
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oh no |
/hold |
aojea
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Sep 13, 2024
aojea
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Sep 13, 2024
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| func (d *DNSCacheAgent) lookupIP(ctx context.Context, network, host string) ([]net.IP, error) { | ||
| ips, ok := d.cache.get(network, host, expireTimeout) | ||
| if ok { | ||
| klog.V(4).Infof("Cached entries for %s %s : %v", network, host, ips) | ||
| return ips, nil | ||
| } | ||
| ips, err := d.resolver.LookupIP(ctx, network, host) | ||
| if err != nil { | ||
| // cache empty answers | ||
| if e, ok := err.(*net.DNSError); !ok || !e.IsNotFound { | ||
| return nil, err | ||
| } | ||
| } | ||
| d.cache.add(network, host, ips) | ||
| klog.V(4).Infof("Caching new entries for %s %s : %v", network, host, ips) | ||
| return ips, nil | ||
| } |
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This is the important thing to solve:
- cache agent has the pod parameters ndots and searches (it is deployed as a hostnetwork pod with dnsPoliyc: ClusterFirstWithHostNet)
- when pod ask for
kubernetes.defaultthe resolver on the pod will append allsearchesuntil the number ofndots
I0913 09:47:13.869272 1 dnscache.go:249] UDP connection from 100.96.1.14:59154
I0913 09:47:13.869338 1 dnscache.go:283] dialing from 100.64.0.10:53 to 100.96.1.14:59154
I0913 09:47:13.869435 1 dnscache.go:444] starting parsing packet
I0913 09:47:13.869469 1 dnscache.go:559] DNS A request for kubernetes.default.default.svc.cluster.local.
I0913 09:47:13.869484 1 dnscache.go:658] Cached entries for ip4 kubernetes.default.default.svc.cluster.local. : []
I0913 09:47:13.869498 1 dnscache.go:496] answer correct
I0913 09:47:13.870417 1 dnscache.go:249] UDP connection from 100.96.1.14:52573
I0913 09:47:13.870465 1 dnscache.go:283] dialing from 100.64.0.10:53 to 100.96.1.14:52573
I0913 09:47:13.870550 1 dnscache.go:444] starting parsing packet
I0913 09:47:13.870578 1 dnscache.go:559] DNS A request for kubernetes.default.svc.cluster.local.
I0913 09:47:13.871531 1 dnscache.go:669] Caching new entries for ip4 kubernetes.default.svc.cluster.local. : [100.64.0.1]
I0913 09:47:13.871627 1 dnscache.go:568] DNS A request for kubernetes.default.svc.cluster.local. ips: [100.64.0.1]
I0913 09:47:13.871640 1 dnscache.go:496] answer correct
I0913 09:47:13.874943 1 dnscache.go:249] UDP connection from 100.96.1.14:55191
I0913 09:47:13.874996 1 dnscache.go:283] dialing from 100.64.0.10:53 to 100.96.1.14:55191
I0913 09:47:13.875084 1 dnscache.go:444] starting parsing packet
I0913 09:47:13.875150 1 dnscache.go:589] DNS AAAA request for kubernetes.default.svc.cluster.local.
I0913 09:47:13.876114 1 dnscache.go:669] Caching new entries for ip6 kubernetes.default.svc.cluster.local. : []
I0913 09:47:13.876212 1 dnscache.go:496] answer correct
This means that the cache CAN know the original question of the pod and can deduplicate all these queries to answer on the first query ... this will be a big improvement since it will allow to remove all the amplification added by searches @thockin
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Change-Id: If90379e54b08ffab3c909b889e9dd532931aaf3e
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Pass through cache for A and AAAA records with ttl 30 seconds
Only captures Pods requests
TODO: