fastapi-observer 1.3.1

Zero-glue FastAPI observability with security presets and runtime controls

fastapi-observer

Zero-glue observability for FastAPI.

fastapi-observer gives you structured JSON logs, request correlation, Prometheus metrics, OpenTelemetry tracing, security redaction presets, and runtime controls in one install step and one function call.

Supported Python versions: 3.10 to 3.14

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Compatibility Matrix

Component	Supported / Tested
Python	3.10 to 3.14 (CI matrix)
FastAPI	>=0.129.0
Starlette	>=0.52.1
pydantic-settings	>=2.10.1
Prometheus backend	prometheus-client>=0.24.1 (optional extra)
OpenTelemetry	opentelemetry-api/sdk/exporter>=1.39.1 (optional extra)
Loguru bridge	loguru>=0.7.2 (optional extra)

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Why This Package Exists

Most FastAPI services eventually need the same observability plumbing:

• Structured JSON logging
• Request and trace correlation
• Metrics for dashboards and alerts
• OpenTelemetry setup
• Redaction/sanitization for sensitive data
• Runtime controls for incident response

Teams usually implement this as custom glue code in every service. That costs engineering time and creates drift between services.

fastapi-observer replaces this repeated wiring with a consistent, secure-by-default setup.

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Sponsor

If this library saves you engineering time, you can support maintenance here:

buymeacoffee.com/FYbPCSu

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What You Get Immediately

After one call to install_observability():

Capability	Included	Default
Structured JSON logs	Yes	Enabled
Request ID correlation	Yes	Enabled
Trace/span IDs in logs	Yes (with OTel)	Off until OTel enabled
Prometheus /metrics	Yes	Off until metrics_enabled=True
Native FastAPI Lifespan	Yes	Explicit opt-in via observability_lifespan
Auto-discovery	Yes	Excluded routes (/docs, etc.) & DB engines
Sensitive-data redaction	Yes	Enabled
Security presets (strict, pci, gdpr)	Yes	Available
Runtime control endpoint	Yes	Off until enabled
Plugin hooks for enrichment/hooks	Yes	Available

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Install

# Core (logging + metrics + security)
pip install fastapi-observer

# Prometheus metrics support
pip install "fastapi-observer[prometheus]"

# Loguru coexistence bridge support
pip install "fastapi-observer[loguru]"

# OpenTelemetry tracing/logs support
pip install "fastapi-observer[otel]"

# Everything
pip install "fastapi-observer[all]"

Import path:

import fastapiobserver

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5-Minute Quick Start

5-Minute Quick Start ("Zero-Glue")

You can configure the entire library via environment variables simply by calling install_observability(app).

export APP_NAME="orders-api"
export SERVICE_NAME="orders"
export ENVIRONMENT="production"
export METRICS_ENABLED="true"

# Optional: Set a profile ("development" or "production") to auto-configure log levels, queues, and redaction strictness
export OBS_PROFILE="production"

from fastapi import FastAPI
from fastapiobserver import install_observability

app = FastAPI()

# Wires up logging, metrics, OTel, and security automatically from env vars
install_observability(app)

@app.get("/orders/{order_id}")
def get_order(order_id: int) -> dict[str, int]:
    return {"order_id": order_id}

@app.get("/hidden", include_in_schema=False)
def hidden_endpoint():
    # This endpoint is automatically excluded from
    # Prometheus metrics and OTel tracing.
    return {"status": "ok"}

Run:

uvicorn main:app --reload

Now you have:

• Structured request logs on every request
• Request ID propagation
• Sanitized event payloads (enforced by the production profile)
• Prometheus metrics at /metrics

Environment Profiles (OBS_PROFILE)

To dramatically reduce boilerplate, you can use the OBS_PROFILE environment variable to automatically set sensible defaults for your environment:

• OBS_PROFILE=development: Forces LOG_LEVEL=DEBUG and disables any OpenTelemetry network overhead to keep local development fast and noisy.
• OBS_PROFILE=production: Forces LOG_LEVEL=INFO, optimizes internal queues for massive throughput (LOG_QUEUE_MAX_SIZE=20000), and enforces the strict security redaction preset.

(Explicit env vars or Python arguments will always override profile defaults).

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Documentation Map

For deep-dive documentation, please explore the official documentation site (or read the docs/ folder directly):

• Security & Presets
• Environment Variables
• Runtime Control
• OpenTelemetry
• Logtail Sink
• Audit Logging
• Database Tracing
• GraphQL Support
• Architecture & Operations
• Production Deployment
• Performance Tuning
• Advanced Operations