OTTL Playground Autocomplete Implementation Summary

[jsvd]

The implementation adds version-accurate OTTL (OpenTelemetry Transformation Language) autocomplete, validation, and IDE-like features to the ottl-playground web application. The features adapt automatically based on which collector version is selected.

Architecture

pkg/ottl/metadata/           # Upstream-ready metadata extraction
  * metadata.go              # Core types: FunctionInfo, ParameterInfo, PathInfo, EnumInfo
  * introspect.go            # Reflection-based factory introspection
  * functions.go             # Function extraction from StandardFuncs registry
  * contexts.go              # Context paths and enums (log, span, metric, etc.)

wasm/
  * main.go                  # Added 6 new WASM exports
  * internal/metadata.go     # Bridge between pkg/ottl/metadata and WASM
  * internal/validator.go    # Native OTTL parser validation dispatcher
  * internal/validator_ptr.go    # Validators for OTTL v0.142.0+ (pointer contexts)
  * internal/validator_noptr.go  # Validators for older OTTL versions
  * internal/completion_context.go # Lexer-based completion context detection

web/src/components/
  * ottl-completion.js       # CodeMirror 6 extensions
  * panels/config-panel.js   # Integrates extensions into editor
  * playground.js            # Clears cache on version change

Features Implemented

1. Autocompletion

• Function completions with parameter snippets
• Context-aware path completions (body, attributes, trace_id, etc.)
• Enum completions (SEVERITY_NUMBER_, SPAN_KIND_, etc.)
• Triggers: Cmd+., Alt+Space, or typing

2. Signature Help

• Shows function signature while typing arguments
• Highlights current parameter
• Updates as cursor moves between arguments

3. Validation/Linting

• Uses native OTTL parsers (ottllog.NewParser, etc.)
• Real-time squiggly underlines for errors
• Accurate error positioning within statements
• Context-aware (log, span, metric, datapoint, resource, scope)

4. Hover Documentation

• Function hover: signature, parameters, editor vs converter
• Path hover: type, description, key support
• Enum hover: name and numeric value

5. Go-to-Definition

• Cmd/Ctrl+Click on function names
• Opens OTTL documentation on GitHub

Version Accuracy

All metadata is extracted at WASM compile time via reflection:

// pkg/ottl/metadata/functions.go
func ExtractStandardFunctions[K any]() []FunctionInfo {
    factories := ottlfuncs.StandardFuncs[K]()  // Version-specific!
    return ExtractAndSortFunctions(factories)
}

WASM Exports

// Available on window after WASM loads
window.getOTTLFunctions()           // All functions with parameters
window.getContextPaths(context)     // Paths for log/span/metric/etc.
window.getContextEnums(context)     // Enums for the context
window.getOTTLMetadata()            // Complete metadata bundle
window.validateStatements(config, dataType, payload, executor)
window.getCompletionContext(statement)  // Lexer-based cursor context

Multi-Version Support

Tested with two WASM binaries:

• ottlplayground-v0.142.0.wasm
• ottlplayground-v0.138.0.wasm

Usage Flow

1. User selects version from dropdown
2. Corresponding WASM binary loads
3. clearOTTLMetadataCache() called
4. On first completion request, metadata fetched from WASM
5. Functions/paths/enums reflect exact version capabilities
6. Validation uses native parsers from that version