Chain Input

Use the chain input to load data from multiple sources into the watch execution context when the watch is triggered. The inputs in a chain are processed in order and the data loaded by an input can be accessed by the subsequent inputs in the chain.

The chain input enables you perform actions based on data from multiple sources. You can also use the data collected by one input to load data from another source.

For example, the following chain input loads data from an HTTP server using the path set by a simple input:

"input" : {
  "chain" : {
    "inputs" : [ 
        "first" : {
          "simple" : { "path" : "/_search" }
        "second" : {
          "http" : {
            "request" : {
              "host" : "localhost",
              "port" : 9200,
              "path" : "{{ctx.payload.first.path}}" 

The inputs in a chain are specified as an array to guarantee the order in which the inputs are processed. (JSON does not guarantee the order of arbitrary objects.)

Loads the path set by the first input.

Accessing Chained Input Data

To reference data loaded by a particular input, you use the input’s name, ctx.payload.<input-name>.<value>.