Logstash env configuration to set the elastic search url

Hi, I am running logstash docker container and need to know which env to use to tell logstash where to find the elasticsearch server.

[2020-10-01T11:37:39,829][WARN ][logstash.licensechecker.licensereader] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>"http://elasticsearch:9200/", :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://elasticsearch:9200/][Manticore::ResolutionFailure] elasticsearch: Name or service not known"}

any thoughts?

I want to change the value http://elasticsearch:9200 to a different value using an env instead of a configuration file.

If it were an elasticsearch output then you could do that, but I believe the licence check always uses a value from logstash.yml