Upgrade ES 7.17.10 > 8.6.2

Hello. I'm a complete newbie to ES. please help me, I need to update the cluster, what is the best or correct way to do this. which way to go? 9 nodes, docker, number_of_replics = 0.kibana and logstash are not used.

cluster.name: elastic7_selfhosted
indices.breaker.total.use_real_memory: false
indices.recovery.max_bytes_per_sec: 600mb
indices.fielddata.cache.size:  40%
indices.breaker.fielddata.limit: 40%
indices.breaker.request.limit: 60%
node.name: name.domain.group
node.master: true
node.data: true
network.host: 0.0.0.0
network.publish_host: 10.33.202.73
http.port: 9200
cluster.initial_master_nodes: ["10.33.202.73","10.33.202.74","10.33.202.75","10.33.202.76","10.33.202.77","10.33.202.78","10.33.202.79","10.33.202.80","10.33.202.81"]
discovery.seed_hosts: ["10.33.202.74","10.33.202.75","10.33.202.76","10.33.202.77","10.33.202.78","10.33.202.79","10.33.202.80","10.33.202.81"]
script.max_compilations_rate: 100/1m
transport.port: 9300
http.compression: true
discovery.type: zen
ingest.geoip.downloader.enabled: false
discovery.zen.minimum_master_nodes: 5

Kibana upgrade assistant can help you. It will show depreciated cluster settings, incompatible index settings, indices that you need to reindex or remove. Also, it will guide you the upgrade steps like get snapshot before start upgrading your cluster to the newest version.

Check this out: https://www.youtube.com/watch?v=BOS0weyi-HY