If there's no logs indexed we should alert.
Looks like after I90d4951d0 the logstash7 cluster has stopped being able to pull logs from kafka:
Plugin: <LogStash::Inputs::Kafka codec=><LogStash::Codecs::JSON id=>"json_4db6c2df-604a-4d27-9bca-4a3c3a6126bf", enable_metric=>true, charset=>"UTF-8">, group_id=>"logstash7-eqiad", topics=>["eqiad.eventgate-logging-external.error.validation"], ssl_truststore_location=>"/etc/logstash/kafka_logging-eqiad.truststore.jks", ssl_truststore_password=><password>, consumer_threads=>3, security_protocol=>"SSL", id=>"input/kafka/eventgate-logging-external-validation-error-eqiad", type=>"eventgate_validation_error", bootstrap_servers=>"logstash1010.eqiad.wmnet:9093,logstash1011.eqiad.wmnet:9093,logstash1012.eqiad.wmnet:9093", tags=>["input-kafka-eventgate-logging-external-validation-error-eqiad", "kafka", "es", "eventgate"], enable_metric=>true, auto_commit_interval_ms=>"5000", client_id=>"logstash", enable_auto_commit=>"true", key_deserializer_class=>"org.apache.kafka.common.serialization.StringDeserializer", value_deserializer_class=>"org.apache.kafka.common.serialization.StringDeserializer", poll_timeout_ms=>100, ssl_endpoint_identification_algorithm=>"https", sasl_mechanism=>"GSSAPI", decorate_events=>false> Error: SSL handshake failed Exception: Java::OrgApacheKafkaCommonErrors::SslAuthenticationException Stack: [2020-07-07T09:40:09,503][ERROR][logstash.javapipeline ] A plugin had an unrecoverable error. Will restart this plugin. Pipeline_id:main