cap-js-log-control

CAP plugin for controlling CDS logger verbosity and OpenTelemetry DiagLogger noise — reduce log clutter, surface real errors.

Problem

SAP CAP applications on Cloud Foundry generate excessive log noise that buries real errors:

• odata logger — logs every incoming OData request with full HTTP headers JSON blobs
• remote logger — logs every outgoing remote service call with full headers
• OpenTelemetry DiagLogger — @cap-js/telemetry OTLP gRPC exporters emit diagnostic logs that bypass cds.log entirely

Before:

STDOUT {"level":"info","logger":"odata","msg":"POST /assets/$batch",...<3KB of headers>}
STDOUT {"level":"debug","logger":"remote","msg":"GET <api>/... Executing via @sap-cloud-sdk",...}
STDERR ExporterError: Export... failed  [repeated 50x from OTel gRPC]
STDERR Error: The request has no query  ← REAL error, buried

After:

STDERR Error: The request has no query  ← now visible immediately

Installation

npm install cap-js-log-control

CAP auto-discovers the plugin via cds-plugin.js — no code changes needed.

Configuration

Quick Start (zero config)

The plugin works out of the box with sensible defaults:

• odata → warn
• remote → warn
• telemetry → warn
• OpenTelemetry DiagLogger → ERROR

Plugin Config (cds.logControl)

Add to package.json or .cdsrc.json:

{
  "cds": {
    "logControl": {
      "enabled": true,
      "otelDiagLevel": "ERROR",
      "levels": {
        "odata": "warn",
        "remote": "warn",
        "telemetry": "warn"
      }
    }
  }
}

Native CDS Log Levels (also supported)

You can also use the standard CDS log.levels format — the plugin reads both:

{
  "cds": {
    "[development]": {
      "log": {
        "levels": {
          "odata": "error",
          "remote": "error"
        }
      }
    }
  }
}

Priority: cds.logControl.levels overrides cds.log.levels when both are set for the same logger.

Per-Profile Overrides

Use CAP profiles to tune log levels per environment:

{
  "cds": {
    "logControl": {
      "enabled": true,
      "levels": {
        "odata": "warn",
        "remote": "warn"
      }
    },
    "[development]": {
      "logControl": {
        "levels": {
          "odata": "error",
          "remote": "error"
        }
      }
    },
    "[production]": {
      "logControl": {
        "otelDiagLevel": "WARN"
      }
    }
  }
}

Disable the Plugin

{
  "cds": {
    "logControl": {
      "enabled": false
    }
  }
}

Config Reference

| Option | Type | Default | Description | |--------|------|---------|-------------| | logControl.enabled | boolean | true | Master switch — set false to disable all log control | | logControl.levels | Record<string, string> | { odata: 'warn', remote: 'warn', telemetry: 'warn' } | Map of CDS logger names to log levels | | logControl.otelDiagLevel | string | 'ERROR' | OpenTelemetry DiagLogger level |

CDS Log Levels

silent | error | warn | info | debug | verbose | silly

OTel DiagLogger Levels

NONE | ERROR | WARN | INFO | DEBUG | VERBOSE | ALL

How It Works

1. Runs at module load time — not inside a lifecycle hook — because logger noise starts during CDS bootstrap before cds.once('served') fires.
2. Controls CDS loggers — calls cds.log(name).setLevel(level) for each configured logger.
3. Controls OTel DiagLogger — sets diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.ERROR) to suppress OTLP exporter retry chatter.
4. Does NOT redirect stdout/stderr — all logs still flow to CF Loggregator for cloud logging.
5. Does NOT patch console.log — only reduces log generation at the source.

What This Plugin Does NOT Do

• Does NOT redirect or wrap process.stdout / process.stderr
• Does NOT patch console.log / console.error
• Does NOT affect cloud logging — all generated logs still flow to CF Loggregator
• Does NOT disable @cap-js/telemetry or OTLP exporters — only reduces their diagnostic output

Development

npm install
npm run build
npm test

License

Apache-2.0