This topic seems to get posted again and again, and I've gone through all the other answers with no luck.
I'm using version 7.2.0. I'm trying to do a plain-vanilla install on EC2. I have two nodes in the same VPC, same subnet, same security group, built from the same AMI.
On the command line I can do "aws ec2 describe-instances" and see the other instance just fine, which suggests that the IAM user is properly configured.
My elasticsearch.yml:
discovery.seed_providers: ec2
discovery.ec2.groups: my-security-group
network.host: [ site , local , eth0 ]
I've added the aws access key and secret key to the keystore per the instructions here:
https://www.elastic.co/guide/en/elasticsearch/plugins/current/discovery-ec2-usage.html
I'm starting the node using systemd. It starts up just fine.
The node starts up just fine and contains this message:
using discovery type [zen] and seed hosts providers [settings, ec2]
Later, it says "elected-as-master", and "nodes joined" includes only itself.
What am I missing? How do I debug this?