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Following is an illustration of an API call that fetches metrics from the Metrics backend service using Ambari API.
CLUSTER
E.g.: Dashboard metrics : Fetch load average across all nodes of a cluster
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Field | Value | Comment |
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Start time | 1430844925 | Start time for the time range. (Epoch) |
End time | 1430848525 | End time of the time range. (Epoch) |
Step | 15 | Default step, this is used only for zero padding or null padding if the padding interval cannot be determined from the retrieved data. |
HOST
E.g.: Host metrics: Get the cpu utilization on a particular host in the cluster
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The request part of the above API call selects the host which is queried while the predicate part includes the metric names with time range query.
COMPONENT
E.g.: Service metrics: Get the capacity utilization metrics aggregated across all datanodes but only the latest value (point in time)
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The request part of the above API call selects the service from the cluster while predicate part includes the metrics names.
HOST COMPONENT
E.g.: Daemon metrics: Get the heap memory usage for active Namenode
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