Add materials for FastAPI OpenTelemetry tutorial (#791)

* Add materials for FastAPI OpenTelemetry tutorial

* Sync with tutorial after TR

* Fix README formatting and update tutorial link

* Organize imports

---------

Co-authored-by: Bartosz Zaczyński <bartosz.zaczynski@gmail.com>

Author: yukaty

fastapi-opentelemetry/README.md

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+# How to Integrate OpenTelemetry With a FastAPI App
+
+This folder contains sample code for the Real Python tutorial [How to Integrate OpenTelemetry With a FastAPI App]([https://realpython.com/](https://realpython.com/fastapi-opentelemetry/)).

fastapi-opentelemetry/main.py

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+import logging
+
+from fastapi import FastAPI
+from opentelemetry import trace
+
+app = FastAPI()
+tracer = trace.get_tracer(__name__)
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+
+def simulate_db_query(user_id: int):
+    with tracer.start_as_current_span("db_query") as span:
+        span.set_attribute("db.system", "postgresql")
+        span.set_attribute("user.id", user_id)
+
+        trace_id = format(span.get_span_context().trace_id, "032x")
+        span_id = format(span.get_span_context().span_id, "016x")
+
+        if user_id == 999:
+            logger.error(
+                "DB query failed for user %s. trace_id=%s, span_id=%s",
+                user_id,
+                trace_id,
+                span_id,
+            )
+            raise ValueError("Database connection lost!")
+
+        logger.info(
+            "Executing DB query for user %s. trace_id=%s, span_id=%s",
+            user_id,
+            trace_id,
+            span_id,
+        )
+        return {"name": "Demo User", "role": "admin"}
+
+
+@app.get("/users/{user_id}")
+def get_user(user_id: int):
+    logger.info("Received request for user %s", user_id)
+    try:
+        data = simulate_db_query(user_id)
+        return {"status": "success", "data": data}
+    except ValueError:
+        return {"status": "error", "message": "Failed to fetch user"}
+
+
+@app.get("/")
+def read_root():
+    return {"message": "Hello, OpenTelemetry!"}

fastapi-opentelemetry/requirements.txt

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+annotated-doc==0.0.4
+annotated-types==0.7.0
+anyio==4.14.0
+asgiref==3.11.1
+certifi==2026.6.17
+charset-normalizer==3.4.7
+click==8.4.1
+fastapi==0.138.0
+googleapis-common-protos==1.75.0
+grpcio==1.81.1
+h11==0.16.0
+idna==3.18
+opentelemetry-api==1.42.1
+opentelemetry-distro==0.63b1
+opentelemetry-exporter-otlp==1.42.1
+opentelemetry-exporter-otlp-proto-common==1.42.1
+opentelemetry-exporter-otlp-proto-grpc==1.42.1
+opentelemetry-exporter-otlp-proto-http==1.42.1
+opentelemetry-instrumentation==0.63b1
+opentelemetry-instrumentation-asgi==0.63b1
+opentelemetry-instrumentation-fastapi==0.63b1
+opentelemetry-proto==1.42.1
+opentelemetry-sdk==1.42.1
+opentelemetry-semantic-conventions==0.63b1
+opentelemetry-util-http==0.63b1
+packaging==26.2
+protobuf==6.33.6
+pydantic==2.13.4
+pydantic_core==2.46.4
+requests==2.34.2
+starlette==1.3.1
+typing-inspection==0.4.2
+typing_extensions==4.15.0
+urllib3==2.7.0
+uvicorn==0.49.0
+wrapt==2.2.2