86 lines
3.4 KiB
Plaintext
86 lines
3.4 KiB
Plaintext
[[cat-health]]
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== cat health
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`health` is a terse, one-line representation of the same information
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from `/_cluster/health`.
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[source,js]
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--------------------------------------------------
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GET /_cat/health?v
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--------------------------------------------------
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// CONSOLE
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// TEST[s/^/PUT twitter\n{"settings":{"number_of_replicas": 0}}\n/]
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[source,txt]
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--------------------------------------------------
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epoch timestamp cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
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1475871424 16:17:04 elasticsearch green 1 1 5 5 0 0 0 0 - 100.0%
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--------------------------------------------------
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// TESTRESPONSE[s/1475871424 16:17:04/\\d+ \\d+:\\d+:\\d+/ s/elasticsearch/[^ ]+/ s/0 -/\\d+ -/ _cat]
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It has one option `ts` to disable the timestamping:
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[source,js]
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--------------------------------------------------
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GET /_cat/health?v&ts=false
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--------------------------------------------------
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// CONSOLE
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// TEST[s/^/PUT twitter\n{"settings":{"number_of_replicas": 0}}\n/]
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which looks like:
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[source,txt]
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--------------------------------------------------
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cluster status node.total node.data shards pri relo init unassign pending_tasks max_task_wait_time active_shards_percent
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elasticsearch green 1 1 5 5 0 0 0 0 - 100.0%
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--------------------------------------------------
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// TESTRESPONSE[s/elasticsearch/[^ ]+/ s/0 -/\\d+ -/ _cat]
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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,sh]
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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 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 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 0
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--------------------------------------------------
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// NOTCONSOLE
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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,sh]
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--------------------------------------------------
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% while true; do curl localhost:9200/_cat/health; sleep 120; done
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1384309446 18:24:06 foo red 3 3 20 20 0 0 1812 0
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1384309566 18:26:06 foo yellow 3 3 950 916 0 12 870 0
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1384309686 18:28:06 foo yellow 3 3 1328 916 0 12 492 0
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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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// NOTCONSOLE
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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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