gemini-cli/docs/local-development.md

Local development guide

This guide provides instructions for setting up and using local development features, such as tracing.

Tracing

Traces are OpenTelemetry (OTel) records that help you debug your code by instrumenting key events like model calls, tool scheduler operations, and tool calls.

Traces provide deep visibility into agent behavior and are invaluable for debugging complex issues. They are captured automatically when telemetry is enabled.

Viewing traces

You can view traces using either Jaeger or the Genkit Developer UI.

Using Genkit

Genkit provides a web-based UI for viewing traces and other telemetry data.

1. Start the Genkit telemetry server:

   Run the following command to start the Genkit server:

   npm run telemetry -- --target=genkit
   

   The script will output the URL for the Genkit Developer UI, for example:

   Genkit Developer UI: http://localhost:4000
   

2. Run Gemini CLI:

   In a separate terminal, run your Gemini CLI command:

   gemini
   

3. View the traces:

   Open the Genkit Developer UI URL in your browser and navigate to the Traces tab to view the traces.

Using Jaeger

You can view traces in the Jaeger UI. To get started, follow these steps:

1. Start the telemetry collector:

   Run the following command in your terminal to download and start Jaeger and an OTEL collector:

   npm run telemetry -- --target=local
   

   This command also configures your workspace for local telemetry and provides a link to the Jaeger UI (usually http://localhost:16686).

2. Run Gemini CLI:

   In a separate terminal, run your Gemini CLI command:

   gemini
   

3. View the traces:

   After running your command, open the Jaeger UI link in your browser to view the traces.

For more detailed information on telemetry, see the telemetry documentation.

Instrumenting code with traces

You can add traces to your own code for more detailed instrumentation. This is useful for debugging and understanding the flow of execution.

Use the runInDevTraceSpan function to wrap any section of code in a trace span.

Here is a basic example:

import { runInDevTraceSpan } from '@google/gemini-cli-core';
import { GeminiCliOperation } from '@google/gemini-cli-core/lib/telemetry/constants.js';

await runInDevTraceSpan(
  {
    operation: GeminiCliOperation.ToolCall,
    attributes: {
      [GEN_AI_AGENT_NAME]: 'gemini-cli',
    },
  },
  async ({ metadata }) => {
    // The `metadata` object allows you to record the input and output of the
    // operation as well as other attributes.
    metadata.input = { key: 'value' };
    // Set custom attributes.
    metadata.attributes['custom.attribute'] = 'custom.value';

    // Your code to be traced goes here
    try {
      const output = await somethingRisky();
      metadata.output = output;
      return output;
    } catch (e) {
      metadata.error = e;
      throw e;
    }
  },
);

In this example:

• operation: The operation type of the span, represented by the GeminiCliOperation enum.
• metadata.input: (Optional) An object containing the input data for the traced operation.
• metadata.output: (Optional) An object containing the output data from the traced operation.
• metadata.attributes: (Optional) A record of custom attributes to add to the span.
• metadata.error: (Optional) An error object to record if the operation fails.