Gemini CLI

Gemini CLI is Google’s open-source AI coding agent for the terminal. It emits structured OpenTelemetry data for every session: user prompts, tool calls, model API requests, agent runs, file operations, and token usage. Routing this to Last9 lets you measure adoption, model latency, cost, and tool reliability — within your existing observability stack.

Gemini CLI exports all three OpenTelemetry signal types:

• Traces — spans for tool dispatch, API requests, agent runs (enable with GEMINI_TELEMETRY_TRACES_ENABLED=true)
• Metrics — counters and histograms across session, tool, API, token, file, agent, and process domains
• Logs — structured events for prompts, API requests/responses, slash commands, file operations

What gets exported

Metrics

Log events

gemini_cli.config, gemini_cli.user_prompt, gemini_cli.tool_call, gemini_cli.api_request, gemini_cli.api_response, gemini_cli.api_error, gemini_cli.slash_command, gemini_cli.chat_compression, gemini_cli.conversation_finished, gemini_cli.agent.start, gemini_cli.agent.finish, gemini_cli.model_routing, gemini_cli.file_operation, gen_ai.client.inference.operation.details

Spans

llm_call (with gen_ai.request.model, gen_ai.operation.name, gen_ai.usage.input_tokens, gen_ai.usage.output_tokens, gen_ai.conversation.id)

Prerequisites

1. Last9 account — Sign up at app.last9.io
2. Gemini CLI installed — npm install -g @google/gemini-cli
3. OTLP credentials — Get your endpoint and auth header from Integrations → OpenTelemetry

Setup

Gemini CLI uses GEMINI_TELEMETRY_* env vars for the endpoint configuration, but the underlying OpenTelemetry JS SDK reads standard OTEL_EXPORTER_OTLP_HEADERS for authentication headers — so direct export to Last9 works.

1. Get your Last9 OTLP credentials

   Navigate to Integrations → OpenTelemetry. Copy:

   • OTLP Endpoint (e.g., https://otlp.last9.io or https://otlp-aps1.last9.io:443)
   • Authorization header value (e.g., Basic <base64-token>)

2. Add environment variables to your shell profile

   Add the following to ~/.zshrc, ~/.bashrc, or equivalent:

   # Gemini CLI telemetry switches
   export GEMINI_TELEMETRY_ENABLED=true
   export GEMINI_TELEMETRY_TARGET=local
   export GEMINI_TELEMETRY_OTLP_ENDPOINT="https://<your-last9-otlp-endpoint>"
   export GEMINI_TELEMETRY_OTLP_PROTOCOL=http
   export GEMINI_TELEMETRY_TRACES_ENABLED=true
   
   # Standard OTel env — picked up by the SDK for auth headers
   export OTEL_EXPORTER_OTLP_HEADERS="Authorization=Basic <your-last9-auth-token>"

3. Reload your shell

   source ~/.zshrc

4. Run Gemini CLI

   gemini -p "explain this repo"

5. Verify data is arriving

   • Traces — open Traces in Last9, filter by service.name = gemini-cli. Span llm_call should appear.
   • Metrics — open Metrics, search for gemini_cli_session_count_total, gemini_cli_api_request_count_total, or gemini_cli_token_usage_total
   • Logs — open Logs, filter by service.name = gemini-cli. Look for gemini_cli.user_prompt, gemini_cli.api_request.

Configuration reference

Gemini CLI-specific env vars

Standard OTel env vars (used for auth headers)

Configure via ~/.gemini/settings.json instead of env if you prefer:

{
  "telemetry": {
    "enabled": true,
    "target": "local",
    "otlpEndpoint": "https://<your-last9-otlp-endpoint>",
    "otlpProtocol": "http",
    "traces": true,
    "logPrompts": true
  }
}

Environment variables still need to provide OTEL_EXPORTER_OTLP_HEADERS for auth — the Gemini CLI settings file doesn’t have an OTLP headers field.

Local Collector (optional)

If you want batching, retries, fan-out to multiple backends, or to inject auth headers without modifying user shells, run a local OTel Collector:

docker run -d \
  --name gemini-cli-otel-collector \
  -e LAST9_OTLP_ENDPOINT="https://<your-last9-otlp-endpoint>" \
  -e LAST9_OTLP_AUTH="Basic <your-last9-auth-token>" \
  -p 4317:4317 -p 4318:4318 \
  -v "$(pwd)/otel-collector-config.yaml:/etc/otel/config.yaml:ro" \
  otel/opentelemetry-collector-contrib:0.144.0 \
  --config=/etc/otel/config.yaml

Then point Gemini CLI at the collector:

export GEMINI_TELEMETRY_OTLP_ENDPOINT=http://localhost:4317
export GEMINI_TELEMETRY_OTLP_PROTOCOL=grpc
unset OTEL_EXPORTER_OTLP_HEADERS   # collector handles auth

See the reference example for a complete collector config.

Troubleshooting

• No data in Last9 — confirm echo $GEMINI_TELEMETRY_ENABLED returns true in the shell that ran gemini. Restart shell after editing ~/.zshrc.
• Authentication errors — verify OTEL_EXPORTER_OTLP_HEADERS is Authorization=Basic <token> (note the =, not HTTP colon syntax).
• Traces missing — set GEMINI_TELEMETRY_TRACES_ENABLED=true. Span export is opt-in.
• Metric names — Gemini CLI metrics use dots in source (gemini_cli.session.count) but appear in Last9 with underscores (gemini_cli_session_count_total).

Please get in touch with us on Discord or Email if you have any questions.