LAL Extension: Custom Input/Output Types for Developers

LAL (Log Analysis Language) supports custom input and output types for extending log processing beyond the built-in Log type. This enables receiver plugins and custom modules to define domain-specific log entities (e.g., slow SQL records, sampled traces, network profiling logs).

Overview

LAL provides two extension mechanisms:

1. outputType per rule — set in YAML config to transform logs into custom entities
2. LALSourceTypeProvider SPI — register default input/output types for a receiver plugin

Both are documented in detail in the LAL user guide, including:

• Built-in output types (SlowSQL, SampledTrace)
• Creating custom output types (Source subclass or LALOutputBuilder interface)
• Custom input types for non-standard log formats
• SPI registration for receiver-level defaults

Quick Reference

Per-rule output type (YAML config)

rules:
  - name: slow_sql
    outputType: SlowSQL
    dsl: |
      filter { ... }
      extractor {
        statement log.body
      }
      sink { }

LALSourceTypeProvider SPI (receiver plugin default)

public class MyLayerSourceTypeProvider implements LALSourceTypeProvider {
    @Override
    public String layer() { return "MY_LAYER"; }

    @Override
    public Class<?> inputType() { return MyProtoMessage.class; }

    @Override
    public Class<? extends Source> outputType() { return MyCustomBuilder.class; }
}

Register in META-INF/services/org.apache.skywalking.oap.log.analyzer.v2.spi.LALSourceTypeProvider.

For complete examples and implementation details, see the Output Type section in the LAL documentation.