Ruler: remove trailing period from SRV records returned by discovery dnsnosrva lookups
#7494
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verejoel
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dnsnosrva lookups
verejoel
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dnsnosrva lookupsdnsnosrva lookups
verejoel
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dnsnosrva lookupsdnsnosrva lookups
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Recently ran into an issue with Istio in particular, where leaving the trailing dot on the SRV record returned by `dnssrvnoa` lookups led to an inability to connect to the endpoint. Removing the trailing dot fixes this behaviour. Now, technically, this is a valid URL, and it shouldn't be a problem. One could definitely argue that Istio should be responsible here for ensuring that the traffic is delivered. The problem seems rooted in how Istio attempts to do wildcard matching or URLs it receives - including the dot leads it to lookup an empty DNS field, which is invalid. The approach I take here is actually copied from how Prometheus does it. Therefore I hope we can sneak this through with the argument that 'this is how Prometheus does it', regardless of whether or not this is philosophically correct... Signed-off-by: verejoel <[email protected]>
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In case anyone is interested here is a nice article about the trailing dot from the author of |
saswatamcode
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Jul 9, 2024
jnyi
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Oct 17, 2024
Recently ran into an issue with Istio in particular, where leaving the trailing dot on the SRV record returned by `dnssrvnoa` lookups led to an inability to connect to the endpoint. Removing the trailing dot fixes this behaviour. Now, technically, this is a valid URL, and it shouldn't be a problem. One could definitely argue that Istio should be responsible here for ensuring that the traffic is delivered. The problem seems rooted in how Istio attempts to do wildcard matching or URLs it receives - including the dot leads it to lookup an empty DNS field, which is invalid. The approach I take here is actually copied from how Prometheus does it. Therefore I hope we can sneak this through with the argument that 'this is how Prometheus does it', regardless of whether or not this is philosophically correct... Signed-off-by: verejoel <[email protected]>
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Changes
This is a small change, that strips the trailing dot (.) on records returned by
dnssrvnolookups. While the trailing dot is technically a valid URL, it causes "issues" for some tools (in my case Istio), This PR uses the same approach as Prometheus to strip the trailing dot to look more "usual" so that third-party applications might not complain...Verification
I have had this running in our DEV environment since I opened the PR with no issues.