devops

name	devops
description	DevOps practices, CI/CD pipelines, infrastructure as code, deployment strategies, and database operations. Use when discussing CI/CD, deployment, infrastructure, Terraform, Ansible, Kubernetes, or database schema and migrations.

DevOps

Infrastructure

• Infrastructure as Code (IaC) for all environments.
• Immutable infrastructure over mutable servers.
• Automated rollbacks on deployment failure.
• Secrets management via vault or sealed secrets.
• Monitoring and alerting from day one.

Database Operations

• MySQL VARCHAR key limit: A UNIQUE KEY or INDEX on VARCHAR(N) requires N ≤ 768 when using utf8mb4 (4 bytes per char × 768 = 3072 bytes, the InnoDB max key length). Use VARCHAR(255) for indexed email columns, or TEXT without indexing.
• Init script idempotency: Always use CREATE TABLE IF NOT EXISTS and INSERT IGNORE so scripts are safe to re-run.
• Health checks: MySQL containers should use mysqladmin ping -h 127.0.0.1 as their healthcheck.
• Data persistence: Always mount MySQL data to a named Docker volume - never rely on the container's ephemeral filesystem.
• Backup strategy: Implement automated mysqldump backups to a mounted volume before any schema change.
• Connection testing: After deployment, run mysql -h <host> -u<user> -p<pass> -e "SELECT 1" to verify connectivity before any app code runs.

Deployment Verification

• After every deployment, run a smoke test that touches every service.
• Docker: docker compose ps (all up), curl health endpoints, docker compose logs --tail=20 (no errors).
• Kubernetes: kubectl get pods (all Running), kubectl logs (no crash loops).
• Database: connect and run a lightweight query. Check table schemas match expected.
• Rollback plan must be tested BEFORE the deploy - if it doesn't work in staging, don't deploy to prod.