elasticsearch/docs/reference/cluster.asciidoc
Lee Hinman 80ab366de4 Add API to explain why a shard is or isn't assigned
This adds a new `/_cluster/allocation/explain` API that explains why a
shard can or cannot be allocated to nodes in the cluster. Additionally,
it will show where the master *desires* to put the shard, according to
the `ShardsAllocator`.

It looks like this:

```
GET /_cluster/allocation/explain?pretty
{
  "index": "only-foo",
  "shard": 0,
  "primary": false
}
```

Though, you can optionally send an empty body, which means "explain the
allocation for the first unassigned shard you find".

The output when a shard is unassigned looks like this:

```
{
  "shard" : {
    "index" : "only-foo",
    "index_uuid" : "KnW0-zELRs6PK84l0r38ZA",
    "id" : 0,
    "primary" : false
  },
  "assigned" : false,
  "unassigned_info" : {
    "reason" : "INDEX_CREATED",
    "at" : "2016-03-22T20:04:23.620Z"
  },
  "nodes" : {
    "V-Spi0AyRZ6ZvKbaI3691w" : {
      "node_name" : "Susan Storm",
      "node_attributes" : {
        "bar" : "baz"
      },
      "final_decision" : "NO",
      "weight" : 0.06666675,
      "decisions" : [ {
        "decider" : "filter",
        "decision" : "NO",
        "explanation" : "node does not match index include filters [foo:\"bar\"]"
      } ]
    },
    "Qc6VL8c5RWaw1qXZ0Rg57g" : {
      "node_name" : "Slipstream",
      "node_attributes" : {
        "bar" : "baz",
        "foo" : "bar"
      },
      "final_decision" : "NO",
      "weight" : -1.3833332,
      "decisions" : [ {
        "decider" : "same_shard",
        "decision" : "NO",
        "explanation" : "the shard cannot be allocated on the same node id [Qc6VL8c5RWaw1qXZ0Rg57g] on which it already exists"
      } ]
    },
    "PzdyMZGXQdGhqTJHF_hGgA" : {
      "node_name" : "The Symbiote",
      "node_attributes" : { },
      "final_decision" : "NO",
      "weight" : 2.3166666,
      "decisions" : [ {
        "decider" : "filter",
        "decision" : "NO",
        "explanation" : "node does not match index include filters [foo:\"bar\"]"
      } ]
    }
  }
}
```

And when the shard *is* assigned, the output looks like:

```
{
  "shard" : {
    "index" : "only-foo",
    "index_uuid" : "KnW0-zELRs6PK84l0r38ZA",
    "id" : 0,
    "primary" : true
  },
  "assigned" : true,
  "assigned_node_id" : "Qc6VL8c5RWaw1qXZ0Rg57g",
  "nodes" : {
    "V-Spi0AyRZ6ZvKbaI3691w" : {
      "node_name" : "Susan Storm",
      "node_attributes" : {
        "bar" : "baz"
      },
      "final_decision" : "NO",
      "weight" : 1.4499999,
      "decisions" : [ {
        "decider" : "filter",
        "decision" : "NO",
        "explanation" : "node does not match index include filters [foo:\"bar\"]"
      } ]
    },
    "Qc6VL8c5RWaw1qXZ0Rg57g" : {
      "node_name" : "Slipstream",
      "node_attributes" : {
        "bar" : "baz",
        "foo" : "bar"
      },
      "final_decision" : "CURRENTLY_ASSIGNED",
      "weight" : 0.0,
      "decisions" : [ {
        "decider" : "same_shard",
        "decision" : "NO",
        "explanation" : "the shard cannot be allocated on the same node id [Qc6VL8c5RWaw1qXZ0Rg57g] on which it already exists"
      } ]
    },
    "PzdyMZGXQdGhqTJHF_hGgA" : {
      "node_name" : "The Symbiote",
      "node_attributes" : { },
      "final_decision" : "NO",
      "weight" : 3.6999998,
      "decisions" : [ {
        "decider" : "filter",
        "decision" : "NO",
        "explanation" : "node does not match index include filters [foo:\"bar\"]"
      } ]
    }
  }
}
```

Only "NO" decisions are returned by default, but all decisions can be
shown by specifying the `?include_yes_decisions=true` parameter in the
request.

Resolves #14593
2016-03-28 15:21:02 -06:00

50 lines
1.3 KiB
Text

[[cluster]]
= Cluster APIs
[partintro]
--
["float",id="cluster-nodes"]
== Node specification
Most cluster level APIs allow to specify which nodes to execute on (for
example, getting the node stats for a node). Nodes can be identified in
the APIs either using their internal node id, the node name, address,
custom attributes, or just the `_local` node receiving the request. For
example, here are some sample executions of nodes info:
[source,js]
--------------------------------------------------
# Local
curl localhost:9200/_nodes/_local
# Address
curl localhost:9200/_nodes/10.0.0.3,10.0.0.4
curl localhost:9200/_nodes/10.0.0.*
# Names
curl localhost:9200/_nodes/node_name_goes_here
curl localhost:9200/_nodes/node_name_goes_*
# Attributes (set something like node.rack: 2 in the config)
curl localhost:9200/_nodes/rack:2
curl localhost:9200/_nodes/ra*:2
curl localhost:9200/_nodes/ra*:2*
--------------------------------------------------
--
include::cluster/health.asciidoc[]
include::cluster/state.asciidoc[]
include::cluster/stats.asciidoc[]
include::cluster/pending.asciidoc[]
include::cluster/reroute.asciidoc[]
include::cluster/update-settings.asciidoc[]
include::cluster/nodes-stats.asciidoc[]
include::cluster/nodes-info.asciidoc[]
include::cluster/nodes-hot-threads.asciidoc[]
include::cluster/allocation-explain.asciidoc[]