plain.connect

Connect your Plain app to Plain Cloud via OTLP export.

• Overview
• Settings
• Sampling
• What gets exported
• Observer coexistence
• FAQs
• Installation

Overview

You can use plain.connect to export traces, metrics, and logs from your Plain app to Plain Cloud. The framework already instruments itself with OpenTelemetry spans and histograms — plain.connect activates them by providing the OTLP exporters and bridges Python's logging module into OTLP log records.

Set one environment variable and your app starts pushing telemetry:

PLAIN_CONNECT_EXPORT_TOKEN=your-token

If CONNECT_EXPORT_TOKEN is not set, the package is a no-op — safe to install without configuration.

Settings

All settings can be set via PLAIN_-prefixed environment variables or in app/settings.py.

Sampling

By default, all traces are exported. To reduce volume, set a sample rate:

CONNECT_TRACE_SAMPLE_RATE = 0.1  # Export 10% of traces

Metrics are not affected by sampling — histograms aggregate in-process and export periodically regardless of the trace sample rate.

What gets exported

Traces — HTTP request spans and database query spans instrumented by the framework.

Metrics — OTel histograms like db.client.query.duration, aggregated and pushed every 60 seconds.

Logs — Records from the plain and app loggers, plus anything propagating to the root logger, are bridged into OTLP log records and exported with trace_id / span_id set from the active span. The minimum severity is controlled by CONNECT_LOG_LEVEL (default INFO); the root logger's level is widened to that floor when needed so libraries using getLogger(__name__) reach the exporter. To prevent feedback loops, two sources are skipped on the export path: the opentelemetry namespace, and any record emitted from inside the OTLP exporter's background thread (e.g. urllib3 connection errors raised by the exporter's own HTTP call). Your application's urllib3 logs are exported normally.

Observer coexistence

If plain.observer is also installed, both work simultaneously. plain.connect handles production export while observer provides the local dev toolbar and admin trace viewer. Observer detects the existing TracerProvider and layers its sampler and span processor on top.

FAQs

Do I need plain.observer to use plain.connect?

No. plain.connect works independently. Observer is for local dev tooling; plain.connect is for production export.

What happens if the export endpoint is unreachable?

The OTLP exporters batch and retry automatically. If the endpoint is down, telemetry is dropped after retries — it does not block your application.

Does this add latency to requests?

No. Trace spans are exported in a background thread via BatchSpanProcessor. Metrics are flushed periodically by a background thread. Neither blocks request handling.

Installation

# app/settings.py
INSTALLED_PACKAGES = [
    "plain.connect",
    # ...
]

Place plain.connect before plain.observer in INSTALLED_PACKAGES so it sets up the TracerProvider first.