Description

This role configures an ElasticSearch cluster as part of the ELK Stack for the purpose of storing logs for future querying. This data is aggregated by Logstash for use with the Kibana dashboard.

Usage

The recommended number of hosts in an ES cluster is at least 3. This way with number_of_replicas set to 2 means that if one host goes down we lose none of the data.

For more details read: https://www.elastic.co/guide/en/elasticsearch/guide/current/replica-shards.html

Configuration

The only mandatory configuration is the cluster name in defaults/main.yml:

es_cluster_name: 'my-awesome-cluster'

The only other configuration that makes any difference are the JVM options like the ones related to heap size in:

es_jvm_min_heap: 2g
es_jvm_max_heap: 2g

As the hosts are scaled up to deal with more and more logs we should adjust those in turn.

Known Issues

Because we need to know the Tinc VPN IPs of all the nodes in the ES cluster we need to run the setup modules(gather_facts: true) on them in order to get that. So if this role is not ran for the whole cluster it will fail due to lack of value ansible_local.tinc.vpn_ip variable.

We could use Consul for this but it would not work the first time setting up a new cluster.