How to skip invalid json string in ndjson?

[SinotQ]

Question

Hello everyone!

I'm trying to enrich the incoming ndjson with tags and pass it on.

If one of the ndjson lines contains broken json, the entire ndjson will not be passed on.

How can I discard only the broken line?

add_labels.vrl: .a = "1"

send: curl.exe -X POST -H "Content-Type: application/x-ndjson" --data-binary "@data.ndjson" http://127.0.0.1:8090

data.ndjson (if I remove "broken," everything works):

{"b":"2"}
{"c":"2"}broken

While writing this, I noticed that vector is adding its own "path," "source_type," and "timestamp" labels to the output. How can I avoid this?

{"a":"1","b":"2","path":"/","source_type":"http_server","timestamp":"2025-11-15T18:07:13.165017700Z"}
{"a":"1","c":"2","path":"/","source_type":"http_server","timestamp":"2025-11-15T18:07:13.165028100Z"}

Thank you.

Vector Config

sources:
  http_server_in:
    type: http_server
    address: 0.0.0.0:8090
    decoding:
      codec: "json"
    framing:
      method: "newline_delimited"

transforms:
  add_labels:
    inputs: [http_server_in]
    type: remap
    file: add_labels.vrl

sinks:
  out:
    inputs: ["add_labels"]
    type: console
    encoding:
      codec: "json"
    framing:
      method: "newline_delimited"

Vector Logs

No response

[SinotQ]

I found this solution:

Change "codec" for "source" to "bytes".

sources:
  http_server_in:
    type: http_server
    address: 0.0.0.0:8090
    decoding:
      codec: "bytes"
    framing:
      method: "newline_delimited"

transforms:
  add_labels:
    inputs: [http_server_in]
    type: remap
    file: add_labels.vrl

sinks:
  out:
    inputs: ["add_labels"]
    type: console
    encoding:
      codec: "json"
    framing:
      method: "newline_delimited"

In the vrl file:

., err = parse_json(.message)
if err != null { abort }
.a = "1"

The output skips broken JSON lines and doesn't add extra tags:

{"a":"1","b":"2"}

Is this the best solution?

[pront]

Hi @SinotQ, apologies for the late reply. This solution is reasonable. The remap transform with drop_on_abort: true (the default) discards unparseable lines.