Use preferred protocol first when resolving hostname #728
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Prior to this change, LookupIPAddr() is used to do the DNS query, which sends two DNS queries for A/AAAA records, even if the config has preferred protocol set to ip4 and does not allow fallback protocol. This change will change to use LookupIP() with the preferred protocol, and only try fallback protocol if it's set to true. In most cases doing this will save one RTT of DNS query. Signed-off-by: Yuchen Ying <github.com@yegle.net>
brian-brazil
reviewed
Jan 4, 2021
Signed-off-by: Yuchen Ying <github.com@yegle.net>
Signed-off-by: Yuchen Ying <github.com@yegle.net>
Signed-off-by: Yuchen Ying <github.com@yegle.net>
Signed-off-by: Yuchen Ying <github.com@yegle.net>
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Thanks! |
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I wonder if a new version can cut with this PR included? Or alternatively can you publish a nightly docker image? |
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Does the docker image at prom/blackbox-exporter:master include this merge? |
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@crockk It should be even though I'm actually using the master tag image and I see no change in the behavior. Either way this PR will be on 0.19 which for the looks of it it's just around the corner. |
roidelapluie
added a commit
to roidelapluie/blackbox_exporter
that referenced
this pull request
May 28, 2021
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Also related to golang/go#45024, need wait golang 1.17 release and upgrade. |
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Prior to this change, LookupIPAddr() is used to do the DNS query,
which sends two DNS queries for A/AAAA records, even if the config has
preferred protocol set to ip4 and does not allow fallback protocol.
This change will change to use LookupIP() with the preferred protocol,
and only try fallback protocol if it's set to true. In most cases doing
this will save one RTT of DNS query.
Fixes #724