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10 changes: 9 additions & 1 deletion sig-scalability/slos/dns_programming_latency.md
Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,10 @@ from all of them.
DNS will start resolving service name to its newly started backends.
- As a user of vanilla Kubernetes, I want some guarantee how quickly in-cluster
DNS will stop resolving service name to its removed (or unhealthy) backends.
- As a user of vanilla Kubernetes, I wasn some guarantee how quickly newly
- As a user of vanilla Kubernetes, I want some guarantee how quickly newly
create services will be resolvable via in-cluster DNS.
- As a user of vanilla Kubernetes, I want some guarantee how quickly in-cluster
DNS will start resolving headless service hostnames to its newly started backends.

### Other notes
- We are consciously focusing on in-cluster DNS for the purpose of this SLI,
Expand All @@ -37,6 +39,12 @@ The reason for doing it this way is feasibility for efficiently computing that:
in 99% of programmers (e.g. iptables). That requires tracking metrics on
per-change base (which we can't do efficiently).

- The SLI for DNS publishing should remain constant independent of the number of records.
For example, in a headless service with thousands of pods the time between the pod being
assigned an IP and the time DNS makes that IP available in the service's A/AAAA record(s)
should be statisitically consistent for the first Pod and the last Pod.


### How to measure the SLI.
There [network programming latency](./network_programming_latency.md) is
formulated in almost exactly the same way. As a result, the methodology for
Expand Down