Initial commit

This is a FastAPI backend microservice template used with `copier` utility.

Features of applied template are:
- Configuration file processing logic
- Metrics and tracing (both optional) configuration available
- Debug endpoints
- Database migration commands, prepared Alembic environment
- Database usage example in ping_db endpoint
- gitea sanity check pipeline

{{project_slug}}/observability/metrics.py

@@ -0,0 +1,47 @@
+"""Application metrics are defined here."""
+
+from dataclasses import dataclass
+
+from opentelemetry import metrics
+from opentelemetry.sdk.metrics import Counter, Histogram
+
+
+@dataclass
+class Metrics:
+    request_processing_duration: Histogram
+    """Processing time histogram in seconds by `["method", "path"]`."""
+    requests_started: Counter
+    """Total started requests counter by `["method", "path"]`."""
+    requests_finished: Counter
+    """Total finished requests counter by `["method", "path", "status_code"]`."""
+    errors: Counter
+    """Total errors (exceptions) counter by `["method", "path", "error_type", "status_code"]`."""
+
+
+def init_metrics() -> Metrics:
+    meter = metrics.get_meter("{{project_name}}")
+    return Metrics(
+        request_processing_duration=meter.create_histogram(
+            "request_processing_duration",
+            "sec",
+            "Request processing duration time in seconds",
+            explicit_bucket_boundaries_advisory=[
+                0.05,
+                0.2,
+                0.3,
+                0.7,
+                1.0,
+                1.5,
+                2.5,
+                5.0,
+                10.0,
+                20.0,
+                40.0,
+                60.0,
+                120.0,
+            ],
+        ),
+        requests_started=meter.create_counter("requests_started_total", "1", "Total number of started requests"),
+        requests_finished=meter.create_counter("request_finished_total", "1", "Total number of finished requests"),
+        errors=meter.create_counter("request_errors_total", "1", "Total number of errors (exceptions) in requests"),
+    )