Implement SRV records

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2020-01-18 20:12:25 +01:00
parent 63d3dfb0e1
commit 9d912fe2ca
5 changed files with 89 additions and 29 deletions

View File

@@ -24,10 +24,13 @@ endpoints need to be drained from it.
discovered every 10 seconds. The plugin hands out responses that adhere to these assignments. Only
endpoints that are *healthy* are handed out.
Each DNS response contains a single IP address that's considered the best one. *Traffic* will load
balance A and AAAA queries. The TTL on these answer is set to 5s. It will only return successful
responses either with an answer or otherwise a NODATA response. Queries for non-existent clusters
get a NXDOMAIN, where the minimal TTL is also set to 5s.
Each DNS response contains a single IP address (or SRV record) that's considered the best one.
*Traffic* will load balance A, AAAA and SRV queries. The TTL on these answer is set to 5s. It will
only return successful responses either with an answer or otherwise a NODATA response. Queries for
non-existent clusters get a NXDOMAIN, where the minimal TTL is also set to 5s.
When an SRV record is returned an endpoint DNS name is synthesized `endpoint-0.<cluster>.<zone>` that
carries the IP address. Querying for these synthesized names works as well.
The *traffic* plugin has no notion of draining, drop overload and anything that advanced, *it just
acts upon assignments*. This is means that if a endpoint goes down and *traffic* has not seen a new
@@ -37,7 +40,7 @@ Load reporting is not supported for the following reason. A DNS query is done by
Behind this resolver (which can also cache) there may be many clients that will use this reply. The
responding server (CoreDNS) has no idea how many clients use this resolver. So reporting a load of
+1 on the CoreDNS side can results in anything from 1 to 1000+ of queries on the endpoint, making
the load reporting from *trafifc* highly inaccurate.
the load reporting from *traffic* highly inaccurate.
## Syntax
@@ -97,7 +100,6 @@ If monitoring is enabled (via the *prometheus* plugin) then the following metric
* `coredns_traffic_clusters_tracked{}` the number of tracked clusters.
## Examples
~~~