PS.: I can execute your second command using elastic user.
>docker exec -it dockercomposelogs_logstash_1 bash
bash-4.2$ curl -X POST -H "Content-Type: application/json" http://192.168.99.100:9200/logstash-test/_doc/1 -d'{"test":1}' -u elastic:e12345 -vvv
* About to connect() to 192.168.99.100 port 9200 (#0)
* Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 9200 (#0)
* Server auth using Basic with user 'elastic'
> POST /logstash-test/_doc/1 HTTP/1.1
> Authorization: Basic ZWxhc3RpYzplMTIzNDU=
> User-Agent: curl/7.29.0
> Host: 192.168.99.100:9200
> Accept: */*
> Content-Type: application/json
> Content-Length: 10
>
* upload completely sent off: 10 out of 10 bytes