Certificate signed by unknown authority filebeat

[rnkhouse (Ronak Patel)]

I am getting this error from filebeat:

Failed to connect to backoff(elasticsearch(https://elk.example.com:9200)): Get https://elk.example.com:9200: x509: certificate signed by unknown authority
INFO pipeline/output.go:93 Attempting to reconnect to backoff(elasticsearch(https://elk.example.com:9200)) with 1468 reconnect attempt(s)
INFO [publish] pipeline/retry.go:189 retryer: send unwait-signal to consumer
INFO [publish] pipeline/retry.go:191 done
NFO [publish] pipeline/retry.go:166 retryer: send wait signal to consumer
INFO [publish] pipeline/retry.go:168 done

However, elasticsearch is having valid SSL by letsencrypt. (This is not a self-signed certificate).

Filebeat kubernetes config:

output.elasticsearch:
  hosts: ['${ELASTICSEARCH_HOST:elasticsearch}:${ELASTICSEARCH_PORT:9200}']
  username: ${ELASTICSEARCH_USERNAME}
  password: ${ELASTICSEARCH_PASSWORD}