push metrics to cortex

[Phaniraj L]

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Hi ,

      we have exposed my Cassandra metrics using Cassandra metrics jar(added in Cassandraenvsh) . 

i can view the metrics on the node(`http://localhost:$port/metrics`..)..

 I have centralized cortex(Prometheus) server which is built by our monitoring team. 

How do i push the metrics to cortex server** 

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