Bernard Siebens
c0a44093d9
/healthz checks the database and does a cache ROUND TRIP, not a ping. Both matter: a node that cannot reach Postgres serves nothing, and a cache that accepts writes and returns nothing would have waffle read every feature flag as unset -- so "healthy" has to mean more than "the process is listening", or the load balancer will keep feeding traffic to a node that only looks alive. No auth and no tenant on it: the proxy, and later a load balancer, must reach it on any host. DEPLOYMENT.md is the runbook, and leads with the five things that make this app not a generic Django deploy: the wildcard cert forces DNS-01 (Let's Encrypt will not issue a wildcard over HTTP-01); Redis is required on one server, not two, because of the per-process flag cache; SECURE_PROXY_SSL_HEADER plus Caddy's X-Forwarded-Proto or WebAuthn and the SSL redirect both break; uploads must reach object storage BEFORE the second app server, not during; and invoices need native pango. Also documents why the archive job ships with --commit off, why migrations are run explicitly rather than from the entrypoint, and how to test the restore before the day you need it. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
45 lines
1.3 KiB
Python
45 lines
1.3 KiB
Python
"""Liveness for the proxy today, for a load balancer later.
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Checks the two dependencies whose absence makes the app lie rather than fail: without the
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database it cannot serve anything, and without a shared cache the feature flags drift apart
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between workers. A health check that only proves the process is listening would call that
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healthy.
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"""
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from django.core.cache import cache
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from django.db import connection
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from django.http import JsonResponse
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from django.views.decorators.cache import never_cache
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PROBE_KEY = "healthz"
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@never_cache
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def healthz(request):
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checks = {"database": _database(), "cache": _cache()}
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healthy = all(checks.values())
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return JsonResponse({"status": "ok" if healthy else "degraded", "checks": checks}, status=200 if healthy else 503)
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def _database() -> bool:
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try:
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with connection.cursor() as cursor:
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cursor.execute("SELECT 1")
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cursor.fetchone()
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except Exception:
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return False
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return True
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def _cache() -> bool:
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"""A round trip, not a ping: a cache that accepts writes and returns nothing is worse
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than one that is plainly down, because waffle would read every flag as unset."""
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try:
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cache.set(PROBE_KEY, "ok", 10)
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return cache.get(PROBE_KEY) == "ok"
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except Exception:
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return False
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