75 lines
2.4 KiB
Plaintext
75 lines
2.4 KiB
Plaintext
[[river]]
|
|
= Rivers
|
|
|
|
== Intro
|
|
|
|
A river is a pluggable service running within elasticsearch cluster
|
|
pulling data (or being pushed with data) that is then indexed into the
|
|
cluster.
|
|
|
|
A river is composed of a unique name and a type. The type is the type of
|
|
the river (out of the box, there is the `dummy` river that simply logs
|
|
that it is running). The name uniquely identifies the river within the
|
|
cluster. For example, one can run a river called `my_river` with type
|
|
`dummy`, and another river called `my_other_river` with type `dummy`.
|
|
|
|
[float]
|
|
== How it Works
|
|
|
|
A river instance (and its name) is a type within the `_river` index. All
|
|
different rivers implementations accept a document called `_meta` that
|
|
at the very least has the type of the river (twitter / couchdb / ...)
|
|
associated with it. Creating a river is a simple curl request to index
|
|
that `_meta` document (there is actually a `dummy` river used for
|
|
testing):
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
curl -XPUT 'localhost:9200/_river/my_river/_meta' -d '{
|
|
"type" : "dummy"
|
|
}'
|
|
--------------------------------------------------
|
|
|
|
A river can also have more data associated with it in the form of more
|
|
documents indexed under the given index type (the river name). For
|
|
example, storing the last indexed state can be stored in a document that
|
|
holds it.
|
|
|
|
Deleting a river is a call to delete the type (and all documents
|
|
associated with it):
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
curl -XDELETE 'localhost:9200/_river/my_river/'
|
|
--------------------------------------------------
|
|
|
|
[float]
|
|
== Cluster Allocation
|
|
|
|
Rivers are singletons within the cluster. They get allocated
|
|
automatically to one of the nodes and run. If that node fails, an river
|
|
will be automatically allocated to another node.
|
|
|
|
River allocation on nodes can be controlled on each node. The
|
|
`node.river` can be set to `_none_` disabling any river allocation to
|
|
it. The `node.river` can also include a comma separated list of either
|
|
river names or types controlling the rivers allowed to run on it. For
|
|
example: `my_river1,my_river2`, or `dummy,twitter`.
|
|
|
|
[float]
|
|
== Status
|
|
|
|
Each river (regardless of the implementation) exposes a high level
|
|
`_status` doc which includes the node the river is running on. Getting
|
|
the status is a simple curl GET request to
|
|
`/_river/{river name}/_status`.
|
|
|
|
include::couchdb.asciidoc[]
|
|
|
|
include::rabbitmq.asciidoc[]
|
|
|
|
include::twitter.asciidoc[]
|
|
|
|
include::wikipedia.asciidoc[]
|
|
|