simplekv.conf

input {
  generator {
    message => "baz=bot blah=bar"
    count => 10000000
  }
}

filter {
  kv {}
  mutate {
    add_field => {foo => bar}
  }
}


output {
  stdout {
    codec => dots
  }
}

simplekv.yml

---
graph:
  log-reader:
    component: input-generator
    options: {"message": "baz=bot blah=bar", "count": 10000000}
    to: [main-queue]
  main-queue:
    component: queue-synchronous
    to: [hello-kv]
  hello-kv:
    component: filter-kv
    to: [main-out]
  field-adder:
    component: filter-mutate
    options:
      add_field:
        foo: bar
  main-out:
    component: output-stdout
    options:
      codec: dots