[Logstash Metrics] logstash.node.stats failing to index stats due to error in CEL expression.

[jvalente-salemstate]

I am using the Technical Preview data stream in the Logstash Metrics integration. None of the stats pulled by the API are being indexed to Elasticsearch. If I make the same call to the API using curl, I am getting the expected results.

Here's an example from my dashboard, same results regardless of how far back I search.

When I search data_stream.dataset: logstash.node every single event is including

error.message:failed eval: ERROR: <input>:33:4: no such overload: drop

This looks like it's originating at the end of packages/logstash/data_stream/node_cel/agent/stream/cel.yml.hbs

...

program: |
  get(state.url)
  .as(resp, bytes(resp.Body)
  .decode_json().as(body,
    {"logstash":{"node":{"stats":{
             "events":body.events,
             "jvm":{
                "uptime_in_millis":body.jvm.uptime_in_millis,
                "mem":body.jvm['mem'].drop("pools"),
                "threads":body.jvm.threads
              },
             "queue":body.queue,
             "reloads":body.reloads,
             "process":body.process,
             "os":{
              "cpu":body.process.cpu,
              "cgroup":has(body.os.group) ? body.os.cgroup : {},
             },
             "logstash":{
               "ephemeral_id":body.ephemeral_id,
               "host":body.host,
               "http_address":body.http_address,
               "name":body.name,
               "pipeline":body.pipeline,
               "pipelines":body.pipelines.map(pipeline, pipeline != '.monitoring-logstash', [pipeline]).flatten(),
               "snapshot":body.snapshot,
               "status":body.status,
               "uuid":body.id,
               "version":body.version,
              }
          }}
        }})
  )
  .as(eve, {
    "events":[eve]
  })

This looks like it's related to elastic/mito#55 but I'm not at all familiar with CEL and how its overloads work.

Environment I'm seeing this in:

• Logstash v8.13.1
• Elastic Agent v8.13.1
• Logstash Integration v2.4.3
• Ubuntu 20.04