Chain transform
editChain transform
editA transform that executes an ordered list of configured transforms
in a chain, where the output of one transform serves as the input of the next
transform in the chain. The payload that is accepted by this transform serves as
the input of the first transform in the chain and the output of the last transform
in the chain is the output of the chain
transform as a whole.
You can use chain transforms to build more complex transforms out of the other
available transforms. For example, you can combine a search
transform and a script
transform, as shown in the
following snippet:
"transform" : { "chain" : [ { "search" : { "indices" : [ "logstash-*" ], "body" : { "size" : 0, "query" : { "match" : { "priority" : "error" } } } } }, { "script" : "return [ error_count : ctx.payload.hits.total ]" } ] }
The |
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The first transform in the chain (in this case, a |
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The second and final transform in the chain (in this case, a |
This example executes a count
search on the cluster to look for error
events.
The search results are then passed to the second script
transform. The script
transform extracts the total hit count and assigns it to the error_count
field
in a newly-generated payload. This new payload is the output of the chain
transform and replaces the payload in the watch execution context.