Elasticsearch 7.4 Multi Clustering configuration - elasticsearch

Question

I am trying to make an Elasticsearch cluster with two nodes. Most of the documents in Google are about lower version clustering since they talk about discover.zen.ping.unicast.hosts which 7.4 doesn't have.
Two nodes are AWS EC2 instances.
Each Elasticservice is running fine but I don't think they are clustered. ( _cluster/health , _nodes API).
I made changes in /etc/hosts.
elasticsearch.yml for node-1 :
# ---------------------------------- Cluster -----------------------------------
cluster.name: dsm-001
# ------------------------------------ Node ------------------------------------
node.name: node-1
# ----------------------------------- Paths ------------------------------------
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
# ---------------------------------- Network -----------------------------------
#network.host: 192.168.0.1
http.port: 9200
# --------------------------------- Discovery ----------------------------------
discovery.seed_hosts: ["node-1","node-2"]
cluster.initial_master_nodes: ["node-1","node-2"]
elasticsearch.yaml for node-2 :
# ---------------------------------- Cluster -----------------------------------
cluster.name: dsm-001
# ------------------------------------ Node ------------------------------------
node.name: node-2
# ----------------------------------- Paths ------------------------------------
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
# ---------------------------------- Network -----------------------------------
#network.host: 192.168.0.1
http.port: 9200
# --------------------------------- Discovery ----------------------------------
discovery.seed_hosts: ["node-1","node-2"]
cluster.initial_master_nodes: ["node-1","node-2"]

Answer 1

While the cluster.initial_master_nodes property requires names that match actual elasticsearch node names ("node-1" and "node-2"), the discovery.seed_hosts property expects host names or addresses (e.g. "server1", 192.168.1.12") and not Elasticsearch node names. This is what you need to fix first.
But as you run your nodes in AWS, you are expected to install the EC2 Discovery Plugin to help you locating
the seed addresses of your Elasticsearch nodes (see the Elasticsearch Reference Documentation: EC2 Discovery Plugin)
With Elasticsearch 7 the cluster coordination layer has been rewritten, making your cluster much more robust, but also making the first start-up of a node extremely important. The cluster.initial_master_nodes property is only used when starting up a node for the very first time. If you did so, and your node did not join the expected cluster (and most likely created its own cluster), you need to stop your node, delete the data directory (to clear the cluster state) and restart it.

Answer 2

For Additional Help
Finally, I figured it out.
If Daniel's answer doesn't work for you, add the following.
---------------------------Network-----------------------------------
network.host: Your Public DNS (IPv4) // For example, ec2-1-1-1-1.ap-northeast-1.compute.amazonaws.com
----------------------------Discovery------------------------------------
discovery.seed_hosts : [" ip" , "ip" ] // like Daniel said.
discovery.seed_providers: ec2