Instrument FastAPI with OpenTelemetry

Send traces, logs and metrics from a FastAPI app to Telemetry Machine with OpenTelemetry's zero-code Python instrumentation. No code changes.

Open in Claude

OpenTelemetry's zero-code Python instrumentation traces every request, sends your logging records as logs, and records HTTP metrics. Your code doesn't change.

Create the datasets

Each signal goes to its own dataset. Create three, and an ingest key that can write to all of them, with tm-cli or the MCP server:

$ tm-cli datasets create --name shop-prod-traces --type traces
$ tm-cli datasets create --name shop-prod-logs --type logs
$ tm-cli datasets create --name shop-prod-metrics --type metrics
$ tm-cli api-keys create --name shop-api --dataset shop-prod-traces --dataset shop-prod-logs --dataset shop-prod-metrics

create_dataset { "name": "shop-prod-traces", "signal_type": "traces" }
create_dataset { "name": "shop-prod-logs", "signal_type": "logs" }
create_dataset { "name": "shop-prod-metrics", "signal_type": "metrics" }
create_ingest_key {
  "name": "shop-api",
  "datasets": ["shop-prod-traces", "shop-prod-logs", "shop-prod-metrics"]
}

tm-cli shows the key once, in api_key.api_key. Over MCP, your agent gets it once and saves it in your app's configuration. In the app, create each dataset, then a key for all three under API keys in your organization's settings.

Install

In your app's virtual environment, after your app's own packages:

Terminal

$ pip install opentelemetry-distro opentelemetry-exporter-otlp-proto-http
$ opentelemetry-bootstrap -a install

opentelemetry-bootstrap installs the instrumentation for each library it finds, such as FastAPI, logging and httpx.

Configure

Shell

export TM_INGEST_KEY='<ingest-key>'
export OTEL_SERVICE_NAME=shop-api
export OTEL_EXPORTER_OTLP_ENDPOINT=https://api.telemetrymachine.com
export OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
export OTEL_EXPORTER_OTLP_TRACES_HEADERS="X-API-Key=$TM_INGEST_KEY,X-Dataset-Name=shop-prod-traces"
export OTEL_EXPORTER_OTLP_LOGS_HEADERS="X-API-Key=$TM_INGEST_KEY,X-Dataset-Name=shop-prod-logs"
export OTEL_EXPORTER_OTLP_METRICS_HEADERS="X-API-Key=$TM_INGEST_KEY,X-Dataset-Name=shop-prod-metrics"

Run

Put opentelemetry-instrument in front of the command that starts your app:

Terminal

$ opentelemetry-instrument uvicorn main:app

It works the same with fastapi run, --reload and --workers.

Check it arrived

Send your app a few requests, then open each explorer and choose the dataset:

Traces, shop-prod-traces: one server span per request, named after its route, such as GET /items/{item_id}.
Logs, shop-prod-logs: your logging records, each with its request's trace.trace_id.
Metrics, shop-prod-metrics: http.server.duration, sent once a minute.

Or count spans by name with tm-cli or the MCP server:

$ tm-cli query shop-prod-traces --since 15m --select "name, count(*)" --group-by name

run_query {
  "dataset": "shop-prod-traces",
  "description": "Spans by name",
  "since": "15m",
  "select": "name, count(*)",
  "group_by": "name"
}

Troubleshooting

Requested component 'otlp_proto_grpc' not found: set OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf. The Python distro defaults to gRPC, which Telemetry Machine doesn't accept.
No INFO logs: Python's root logger drops records below WARNING. Call logging.basicConfig(level=logging.INFO) at startup.
A library you added isn't traced: run opentelemetry-bootstrap -a install again.