Add an optional upcheck validation for internal domains

cloudfoundry / bosh-dns-release

BOSH DNS release

Apache License 2.0

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Add an optional upcheck validation for internal domains #59

Closed beyhan closed 4 years ago

beyhan commented 4 years ago

If the validation is activated bosh-dns will periodically check that the internal domain resolution works. If it doesn't work will restart itself.

cf-gitbot commented 4 years ago

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/172760628

The labels on this github issue will be updated when the story is started.

beyhan commented 4 years ago

Remarks on the pr:

I couldn't find any good reason to add tests to the main_test.go,

aashah commented 4 years ago

Learned some more context on what this PR is helping accomplish:

This is a followup to a race condition introduced in 1.18; whereby the currently configured upcheck domain (upcheck.bosh-dns.) was still resolving, but all internal resolutions were failing. This change expands the upcheck assertions to include an actual internal query. We ignore the result because we cannot make the same assertions on the answer, with respect to the IP, as upcheck.bosh-dns..

aashah commented 4 years ago

Looks good to us!

On a separate note, since I imagine you'll be turning this feature one -- we're wondering if there are going to be expected situations where bosh-dns might thrashing (for example during an initial deploy when the VM may still be collecting information for the records.json), and if there should be any backoff logic included in. At most we think this might just generate a lot of logs.

Overall, not too big of a deal, but looking to you for any feedback after turning this on!