Skill — Migration Platform

When this skill activates

This skill activates when the user is designing or implementing a migration platform. This includes schema migration orchestration, data migration tooling, zero-downtime migration automation, migration validation, rollback capabilities, database migration services, migration state machines, dry-run testing, migration scheduling, dependency graph management, and progress tracking.

Mandatory actions when this skill is active

Before writing any code

1. Inventory all systems requiring migration: databases, APIs, services, data pipelines, infrastructure. Quantify: data volume, traffic volume, number of tables/services.
2. Define migration success criteria: zero downtime, data consistency, performance impact under 10%, rollback time under 5 minutes.
3. Identify dependencies: which services depend on the system being migrated. Build dependency graph to determine migration order.
4. Assess risk: classify migrations by risk (low, medium, high, critical). High-risk migrations require dry-run, shadow traffic, and manual approval gates.
5. Establish rollback strategy: forward-compatible schema changes, dual-write period, automated rollback triggers (error rate > 5%).

During implementation

• Migration State Machine: Define states: pending → dry-run → scheduled → in-progress → validating → completed / failed / rolled-back. Track state per migration in database. Expose state via API and dashboard.
• Schema Migration Orchestration: Use tools like Liquibase, Flyway, or Alembic. Migrations should be: idempotent, forward-compatible, backward-compatible during rollout. Apply migrations in stages: additive changes → data migration → breaking changes.
• Zero-Downtime Patterns:
• Expand-Contract: Add new column/table (expand), dual-write to old and new (transition), switch reads to new (cutover), remove old (contract).
• Blue-Green: Deploy new version alongside old, switch traffic atomically, keep old version for quick rollback.
• Shadow Traffic: Mirror production traffic to new system, compare results, cutover when validation passes.
• Data Migration Tooling: Build ETL pipelines for bulk data migration. Include: checkpointing (resume from failure), batching (avoid overwhelming target), validation (row counts, checksums), rate limiting (avoid impacting production). Migrations should be resumable and idempotent.
• Migration Validation: Automated validation checks: data integrity (row counts, checksums), functional correctness (run test suite against new system), performance (latency, throughput within 10% of baseline). Fail migration if any check fails.
• Migration Rollback: Automate rollback when error rate exceeds threshold (5% or 1% for critical systems). Rollback should: revert traffic to old system, preserve data written during migration (dual-write), alert on-call team. Rollback time target: under 5 minutes.
• Dry-Run Testing: Run migrations in staging environment first. Use production-like data volume and traffic patterns. Validate performance, correctness, and rollback. Dry-run should be mandatory for high-risk migrations.
• Migration Scheduling: Schedule migrations during low-traffic windows. Provide manual approval gates for critical migrations. Include: notification to stakeholders, runbook link, on-call team assignment.
• Dependency Graph Management: Build migration dependency graph (service A depends on service B). Enforce migration order: migrate dependencies first, then dependents. Detect circular dependencies and fail early.
• Progress Tracking: Real-time dashboard showing: migration state, percentage complete, error rate, performance metrics, estimated time remaining. Include logs and alerts for anomalies.

After implementation

• Verify migration state machine tracks all migrations with state transitions logged.
• Confirm schema migrations are idempotent, forward-compatible, and backward-compatible during rollout.
• Validate zero-downtime patterns (expand-contract, blue-green, shadow traffic) are implemented.
• Ensure data migration tooling includes checkpointing, batching, validation, and rate limiting.
• Check that migration rollback is automated with under 5-minute rollback time.

Self-check before task completion

• [ ] Migration state machine tracks pending, in-progress, completed, failed, rolled-back states.
• [ ] Schema migrations are idempotent, forward-compatible, and backward-compatible.
• [ ] Zero-downtime patterns (expand-contract, blue-green, shadow traffic) are implemented.
• [ ] Data migration tooling is resumable, idempotent, and includes validation.
• [ ] Migration validation checks data integrity, functional correctness, and performance.
• [ ] Migration rollback is automated and completes in under 5 minutes.
• [ ] Dry-run testing is mandatory for high-risk migrations in production-like staging.
• [ ] Migration scheduling supports manual approval gates and stakeholder notifications.
• [ ] Dependency graph enforces migration order and detects circular dependencies.
• [ ] Progress tracking dashboard shows real-time state, percentage complete, and error rate.