logstash-2018.09.09 0 p STARTED 19 84.1kb 170.108.74.80 1ccd6723-32a1-4fbe-8de4-2fa95babec98
logstash-2018.09.09 0 r UNASSIGNED
logstash-2018.09.09 3 p STARTED 21 22.2kb 170.108.74.80 1ccd6723-32a1-4fbe-8de4-2fa95babec98
logstash-2018.09.09 3 r UNASSIGNED
logstash-2018.09.09 1 p STARTED 18 60.4kb 170.108.74.80 1ccd6723-32a1-4fbe-8de4-2fa95babec98
logstash-2018.09.09 1 r UNASSIGNED
logstash-2018.09.09 2 p STARTED 21 22.8kb 170.108.74.80 1ccd6723-32a1-4fbe-8de4-2fa95babec98
logstash-2018.09.09 2 r UNASSIGNED
[nagios@hnapxlamslog01 ~]$
[nagios@hnapxlamslog01 ~]$
[nagios@hnapxlamslog01 ~]$ curl -XPOST 'localhost:9200/_cluster/reroute' -d '{ "commands" : [ { "allocate" : { "index" : "logstash-2018.09.09", "shard" : 2, "node" : "
1ccd6723-32a1-4fbe-8de4-2fa95babec98", "allow_primary" : true } } ] }'
{"error":"ElasticsearchIllegalArgumentException[[allocate] allocation of [logstash-2018.09.09][2] on node [1ccd6723-32a1-4fbe-8de4-2fa95babec98][FdcoENIXSQWkFbmLdIwkdQ][hnapxlamslog01][inet[/170.108.74.80:9300]]{max_local_storage_nodes=1} is not allowed, reason: [NO(shard cannot be allocated on same node [FdcoENIXSQWkFbmLdIwkdQ] it already exists on)][YES(node passes include/exclude/require filters)][YES(primary is already active)][YES(below shard recovery limit of [2])][YES(allocation disabling is ignored)][YES(allocation disabling is ignored)][YES(no allocation awareness enabled)][YES(total shard limit disabled: [-1] <= 0)][YES(target node version [1.6.0] is same or newer than source node version [1.6.0])][YES(only a single node is present)][YES(shard not primary or relocation disabled)]]","status":400}
[nagios@hnapxlamslog01 ~]$
I don't think your issue and the output you posted are related. If you have nagios log server running on just one machine, it's normal to see half of your shards (all of the replica shards) as 'UNASSIGNED'. They only exist to provide failover, so there's no point in starting that second shard on your main machine.
However, if everything is working properly on a one-instance log server, you should see yellow status, not red. What are the statuses of your main services?