2013-11-14 20:14:39 -05:00
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[[cat-health]]
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2014-05-16 15:43:35 -04:00
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== cat health
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2013-11-14 20:14:39 -05:00
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`health` is a terse, one-line representation of the same information
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from `/_cluster/health`. It has one option `ts` to disable the
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timestamping.
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[source,shell]
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--------------------------------------------------
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% curl 192.168.56.10:9200/_cat/health
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1384308967 18:16:07 foo green 3 3 3 3 0 0 0
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2013-12-02 09:27:41 -05:00
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% curl '192.168.56.10:9200/_cat/health?v&ts=0'
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2013-11-14 20:14:39 -05:00
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cluster status nodeTotal nodeData shards pri relo init unassign
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foo green 3 3 3 3 0 0 0
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--------------------------------------------------
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A common use of this command is to verify the health is consistent
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across nodes:
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[source,shell]
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--------------------------------------------------
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% pssh -i -h list.of.cluster.hosts curl -s localhost:9200/_cat/health
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[1] 20:20:52 [SUCCESS] es3.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0
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[2] 20:20:52 [SUCCESS] es1.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0
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[3] 20:20:52 [SUCCESS] es2.vm
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1384309218 18:20:18 foo green 3 3 3 3 0 0 0
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--------------------------------------------------
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A less obvious use is to track recovery of a large cluster over
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time. With enough shards, starting a cluster, or even recovering after
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losing a node, can take time (depending on your network & disk). A way
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to track its progress is by using this command in a delayed loop:
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[source,shell]
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--------------------------------------------------
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% while true; do curl 192.168.56.10:9200/_cat/health; sleep 120; done
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1384309446 18:24:06 foo red 3 3 20 20 0 0 1812
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1384309566 18:26:06 foo yellow 3 3 950 916 0 12 870
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1384309686 18:28:06 foo yellow 3 3 1328 916 0 12 492
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1384309806 18:30:06 foo green 3 3 1832 916 4 0 0
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^C
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--------------------------------------------------
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In this scenario, we can tell that recovery took roughly four minutes.
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If this were going on for hours, we would be able to watch the
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`UNASSIGNED` shards drop precipitously. If that number remained
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static, we would have an idea that there is a problem.
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[float]
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[[timestamp]]
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=== Why the timestamp?
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You typically are using the `health` command when a cluster is
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malfunctioning. During this period, it's extremely important to
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correlate activities across log files, alerting systems, etc.
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There are two outputs. The `HH:MM:SS` output is simply for quick
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human consumption. The epoch time retains more information, including
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date, and is machine sortable if your recovery spans days.
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