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[tor-bugs] #12006 [Ooni]: Is non-determinism in test helper deployment or MLab-ns API acceptable?
#12006: Is non-determinism in test helper deployment or MLab-ns API acceptable?
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Reporter: cypherpunks | Owner: hellais
Type: defect | Status: new
Priority: normal | Milestone:
Component: Ooni | Version:
Keywords: | Actual Points:
Parent ID: | Points:
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This issue was automatically migrated from github issue
https://github.com/TheTorProject/ooni-probe/issues/118.
Close this ticket with a yes / no.
The MLab `initialize.sh` script for Ooni selects which test helpers bind
to a given port randomly. The requirement is for the same port to provide
multiple distinct test helpers, so the current strategy is to partition
the MLab slices (and thus IP addresses) for each port according to how
many helpers require that port. The random selection accomplishes this in
a stateless / configuration-free manner.
Meanwhile, the probe will use the `mlab-ns` web service to request test
helpers and a collector prior to running a net-test. This service
currently responds non-deterministically (with various constraints and
prioritizations such as scoring based on load).
The question is: Are these two sources of non-determinism a problem?
For scientific repeatability, randomness adds noise. For diagnostic
reasons, determinism can make it simpler to understand logs or report
data. For security reasons, censors might be able to game non-determinism
in a way to favor particular test results. It may be that none of these
concerns are strong enough (also considering the dev cost of removing the
non-determinism).
*If* the answer is "no", there's a dev cost implication for `mlab-ns`
which should be coordinated with MLab.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/12006>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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