Logs

Logging pipeline

Symfony (Monolog, JSON, info level) ──► container standard error ──► Docker
                                                                     │
                                  Promtail (pch_promtail) ◄──────────┘
                                             │
                                  Loki (pch_loki, 1-year retention) ──► off-site copy on the recovery host

• In production, all application logs at info level (requests, e-mail sends, business events) are shipped to Loki and kept for one year.
• Errors also go to Sentry, with the context that precedes them.
• Local Docker logs are size-limited (50 MB × 5 rotation per container); Loki remains the reference.
• A guard (loki-size-guard.sh, cron 04:30) watches the size of the Loki volume.

Read recent logs

cd ~/pch-sig
docker compose -f docker-compose.prod.yml logs --tail 100 backend
docker logs pch_backend --since 30m 2>&1 | grep -iE "error|exception|critical"
docker logs pch_traefik --since 1h 2>&1 | grep -i acme          # certificates

Backend logs are JSON: | grep '"level_name":"ERROR"' isolates errors.

Query Loki

Loki listens on 127.0.0.1:3100 on the production server. From the admin workstation, open an SSH tunnel, then query the API or Grafana:

ssh -L 3100:127.0.0.1:3100 pch-prod
curl -G -s http://127.0.0.1:3100/loki/api/v1/query_range \
  --data-urlencode 'query={container="pch_backend"} |= "exception"' \
  --data-urlencode 'limit=50'

Sample LogQL queries:

Need	Query
Backend errors	{container="pch_backend"} |= "ERROR"
E-mail sends	{container="pch_backend"} |= "SendEmailMessage"
Assistant answers	{container="pch_backend"} |= "Bemba: réponse"

Useful logs by topic

Topic	Where to look
Failed e-mails	docker exec pch_backend php bin/console messenger:failed:show
Grievance digest	/var/log/plainte-digest.log (production)
Assistant indexing	~/assistant-indexer.log
SMTP relay (KoboToolbox)	docker logs smtp_relay (production): status=sent or the rejection reason
Pre-production backups	~/backups/backup.log, ~/backups/gitlab-backup.log
Survey Solutions	~/suso-healthcheck.log (pre-production)
Traefik, certificates	docker logs pch_traefik

Application audit trail

User actions (sign-ins, changes, exports) are recorded in the application: Administration → Audits. See the user guide, Audit section.