Enable discovery of cluster nodes through DNS SRV #1337
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This patch enables CouchDB nodes to check SRV records in DNS for cluster peers and automatically add any discovered peers to the nodes DB. This behavior is disabled by default and can be enabled as follows: [mem3] use_dns_service_discovery = true service_record_name = _couchdb._tcp.example.net If the `service_record_name` is omitted we attempt to generate the appropriate record for the query by prepending _couchdb._tcp. to the DNS domain name portion of the host / VM / container FQDN.
wohali
reviewed
Aug 6, 2018
| construct_service_record() -> | ||
| case config:get("mem3", "service_record_name") of | ||
| undefined -> | ||
| [_ | Domain] = string:tokens(net_adm:localhost(), "."), |
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Tested this on Windows and it fails:
Eshell V8.3 (abort with ^G)
1> [_ | Domain] = string:tokens(net_adm:localhost(), ".").
["DESKTOP-1AA2L3B"]
2> {ok, string:join(["_couchdb", "_tcp" | Domain], ".")}.
{ok,"_couchdb._tcp"}I know this isn't your ideal deployment scenario, but someone's going to try it...and we need to have a fallback when it fails to get a proper domain name.
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I get that you can just override it with mem3:service_record_name, but in case you don't, we should fail semi-gracefully.
3 tasks
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@kocolosk are we abandoning this work in favour of the current -helm approach? |
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If someone wanted to bring it over the finish line I'd be happy to review and merge, but it's a low priority for me given the seedlist capability now adopted by the Helm chart. We can close this PR to clean things up. |
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Overview
This patch enables CouchDB nodes to check SRV records in DNS for cluster peers and automatically add any discovered peers to the nodes DB. This behavior is disabled by default and can be enabled as follows:
[mem3]
use_dns_service_discovery = true
service_record_name = _couchdb._tcp.example.net
If the
service_record_nameis omitted we attempt to generate the appropriate record for the query by prepending _couchdb._tcp. to the DNS domain name portion of the host / VM / container FQDN.I wrote this code a few months back and it passed some smoke tests in Kube but I never opened a PR. Opening it now so I don't forget about it.
Testing recommendations
Related Issues or Pull Requests
Fixes #1108
Checklist