Query regarding "cluster.initial_master_nodes"

Elastic Stack Elasticsearch
1

i am having a cluster in which i have configured master node IPs in "cluster.initial_master_nodes" (ex: cluster.initial_master_nodes:["172.12.12.2:9300","172.12.12.3:9300","172.12.12.4:9300"]) and it worked perfectly. now i am creating a new cluster with domain names(ex: cluster.initial_master_nodes:["es-m1:9300","es-m2:9300","es-m3:9300"]) configured in "cluster.initial_master_nodes". the domain names can resolve to corresponding ip of node. Cluster bootstrapped but master nodes were not discovered.

Went through documentation and found that we must give hostname for "cluster.initial_master_nodes" property.

Identify the initial master nodes by their node.name, which defaults to their hostname. Ensure that the value in cluster.initial_master_nodes matches the node.name exactly.

I would like to know how at first the IP address worked and why domain didn't work. I couldn't find any resolving related exceptions in ES. But i found connection ConnectTransportException(address [127.0.0.1:9300], node [null], requesting [false] connection failed). I don't know what went wrong here. Whether the node name a.k.a hostname must be able to resolve to respective master nodes IP?

2

I don't think you can rely on either approach working. As the docs say, you should be using the node.name values in this setting, not their addresses.

3

Whether node name vs master ip mapping exist in network for the node name to get resolved to master IP?

4

cluster.initial_master_nodes is about node names, it's unrelated to anything to do with networking and there is no DNS lookup happening here (except that node.name defaults to the host name in the first place)

5

Thanks for your help!

6

If so, Any idea on how cluster got bootstrapped when i gave master node IPs in "cluster.initial_master_nodes " like cluster.initial_master_nodes:["172.12.12.2:9300","172.12.12.3:9300","172.12.12.4:9300"] at first?

7

I don't know, sorry. This code hasn't really changed in 6+ years and I won't have time to dig through it in the foreseeable future. Best to stick with the guidance in the manual, even if sometimes a different approach might appear to work for you.

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8

Thanks David for your swift response..It was really helpful.

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9

FYI, Found from cluster bootstrap documentation that we can provide IP:PORT as value for cluster.initial_master_nodes( Link ). The same info is not mentioned in the documentation of cluster.initial_master_nodes.

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10

Ahh yeah you're right, I'd totally forgotten we support that. Still node.name is what I'd recommend, but this is still a working alternative indeed.

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