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Body Storage

When result.bodies.dir is set to a path, Lace executors write response bodies to that directory. The result JSON contains absolute paths to these files -- no body bytes appear in the result JSON itself.

By default, body saving is disabled (result.bodies.dir = false). Enable it in lace.config or with the --save-body / --bodies-dir CLI flags.

Path convention

Body files follow the naming pattern:

{run_base_dir}/call_{index}_response.{ext}
Segment Description
run_base_dir Base directory for this probe run. Configured via result.bodies.dir in lace.config.
index Zero-based call index matching calls[n].index.
ext File extension derived from the content type (e.g. json, xml, txt, html).

Examples

/probe_runs/abc/call_0_response.json
/probe_runs/abc/call_1_response.html

Response bodyPath

The response record includes a bodyPath field.

Response bodyPath: absolute path to the response body file, or null when the body was not captured.

{
  "response": {
    "status": 200,
    "statusText": "OK",
    "headers": {
      "content-type": "application/json"
    },
    "bodyPath": "/probe_runs/abc/call_0_response.json",
    "responseTimeMs": 145
  }
}

bodyNotCapturedReason

When the response bodyPath is null, the bodyNotCapturedReason field explains why.

Value Meaning
"bodyTooLarge" The response body exceeded the configured size limit and was not written.
"notRequested" Body saving is disabled (result.bodies.dir = false, the default).
"timeout" The call timed out before the body could be fully received. 
{
  "response": {
    "status": 200,
    "bodyPath": null,
    "bodyNotCapturedReason": "bodyTooLarge",
    "sizeBytes": 52428800
  }
}

{
  "response": {
    "status": 200,
    "statusText": "OK",
    "headers": {
      "content-type": "application/octet-stream"
    },
    "bodyPath": null,
    "bodyNotCapturedReason": "bodyTooLarge",
    "responseTimeMs": 320,
    "dnsMs": 5,
    "connectMs": 18,
    "tlsMs": 25,
    "ttfbMs": 100,
    "transferMs": 220,
    "sizeBytes": 52428800,
    "dns": {
      "resolvedIps": [
        "10.0.0.1"
      ],
      "resolvedIp": "10.0.0.1"
    },
    "tls": null
  }
}

Configuration

Body saving is controlled by result.bodies.dir in lace.config:

[result.bodies]
dir = "./lace_results/bodies"    # path string = save here, false = don't save
Config key Default Description
result.bodies.dir false Path string: save body files to this directory. false: do not save.

The --save-body CLI flag sets result.bodies.dir to the result path (or system temp) for a single run. The --bodies-dir <path> CLI flag sets result.bodies.dir to the given path explicitly.