feat(prometheus): publish spoolman_build_info metric at startup

spoolman/main.py

@@ -17,7 +17,7 @@
 from spoolman.api.v1.router import app as v1_app
 from spoolman.client import SinglePageApplication
 from spoolman.database import database
-from spoolman.prometheus.metrics import registry
+from spoolman.prometheus.metrics import BUILD_INFO, registry
 
 # Define a console logger
 console_handler = logging.StreamHandler()
@@ -156,13 +156,23 @@ async def startup() -> None:
     # Don't add file logging until we have verified that the data directory is writable
     add_file_logging()
 
+    version = app.version
+    commit = env.get_commit_hash() or ""
+    build_date = env.get_build_date()
+
     logger.info(
         "Starting Spoolman v%s (commit: %s) (built: %s)",
-        app.version,
-        env.get_commit_hash(),
-        env.get_build_date(),
+        version,
+        commit,
+        build_date,
     )
 
+    BUILD_INFO.info({
+        "version": version,
+        "commit": commit,
+        "build_date": str(build_date) if build_date else "",
+    })
+
     logger.info("Using data directory: %s", env.get_data_dir().resolve())
     logger.info("Using logs directory: %s", env.get_logs_dir().resolve())
     logger.info("Using backups directory: %s", env.get_backups_dir().resolve())

spoolman/prometheus/metrics.py

@@ -4,7 +4,7 @@
 from collections.abc import Callable
 
 import sqlalchemy
-from prometheus_client import REGISTRY, Gauge, make_asgi_app
+from prometheus_client import REGISTRY, Gauge, Info, make_asgi_app
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import contains_eager
 
@@ -30,6 +30,8 @@
 FILAMENT_DIAMETER = Gauge(f"{PREFIX}_filament_diameter", "Diameter of filament", ["filament_id"])
 FILAMENT_WEIGHT = Gauge(f"{PREFIX}_filament_weight", "Net weight of filament", ["filament_id"])
 
+BUILD_INFO = Info(f"{PREFIX}_build", "Spoolman build information")
+
 logger = logging.getLogger(__name__)