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from django.db import connections
from django.db.backends.dummy.base import DatabaseWrapper
from prometheus_client import Gauge
from django_prometheus.conf import NAMESPACE
unapplied_migrations = Gauge(
"django_migrations_unapplied_total",
"Count of unapplied migrations by database connection",
["connection"],
namespace=NAMESPACE,
)
applied_migrations = Gauge(
"django_migrations_applied_total",
"Count of applied migrations by database connection",
["connection"],
namespace=NAMESPACE,
)
def ExportMigrationsForDatabase(alias, executor):
plan = executor.migration_plan(executor.loader.graph.leaf_nodes())
unapplied_migrations.labels(alias).set(len(plan))
applied_migrations.labels(alias).set(len(executor.loader.applied_migrations))
def ExportMigrations():
"""Exports counts of unapplied migrations.
This is meant to be called during app startup, ideally by
django_prometheus.apps.AppConfig.
"""
# Import MigrationExecutor lazily. MigrationExecutor checks at
# import time that the apps are ready, and they are not when
# django_prometheus is imported. ExportMigrations() should be
# called in AppConfig.ready(), which signals that all apps are
# ready.
from django.db.migrations.executor import MigrationExecutor
if "default" in connections and (isinstance(connections["default"], DatabaseWrapper)):
# This is the case where DATABASES = {} in the configuration,
# i.e. the user is not using any databases. Django "helpfully"
# adds a dummy database and then throws when you try to
# actually use it. So we don't do anything, because trying to
# export stats would crash the app on startup.
return
for alias in connections.databases:
executor = MigrationExecutor(connections[alias])
ExportMigrationsForDatabase(alias, executor)
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