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Legacy System Migration Readiness Checklist

Tick each item that applies to your system. At the bottom, enter your email to receive the unchecked items — the gaps most likely to block or delay your migration.

0 of 29 checked

Risk levels: High = migration blocker or penalty risk   Medium = significant effort required   Low = manageable with planning

1. Runtime & Operating System

  • PHP version is still officially supported (php.net/supported-versions)PHP 8.1 EOL: Dec 2025 · PHP 7.x: already EOL · PHP 5.x: EOL since 2018 High
  • Operating system receives security updatesSuSE SLES, CentOS, Debian — check vendor EOL dates High
  • All runtime dependencies (Python, Node, Java, etc.) are on supported versions Medium
  • System can be provisioned from scratch without manual stepsOr: is there a runbook that fully documents how to rebuild the server? Medium
  • No self-compiled binaries without documented build instructions High

2. Version Control

  • All application code is stored in Git (or another VCS)FTP deployments, direct server edits, and ZIP archives are red flags High
  • Commit history reflects the actual evolution of the codebaseNot just a single "initial commit" with everything in it Medium
  • Shell scripts and automation are versioned alongside application code Medium
  • Configuration files (non-secret) are versioned; environment-specific values use env vars or a secrets manager Medium
  • The production system reflects exactly what is in the repositoryNo "hotfixes" applied directly to the server that were never committed High

3. Dependency Management

  • PHP dependencies are managed via Composer with a committed composer.lock High
  • All third-party libraries are at versions that support the target PHP version High
  • No vendored or manually patched library copies in the repository Medium
  • External services and APIs the system depends on are documentedDatabases, message queues, monitoring agents, LDAP, payment gateways Medium
  • System integrations (e.g. CheckMK, monitoring agents) are compatible with the target OS Medium

4. Deployment & CI/CD

  • Deployments are automated and reproducibleNo manual file copying, no "only Bob knows how to deploy" High
  • A CI pipeline runs on every merge/pushAt minimum: syntax check and basic test run High
  • Rollback procedure is documented and tested Medium
  • Staging or test environment mirrors production closely enough to catch integration issues Medium
  • Deployment does not require downtime (or planned maintenance windows are formally defined) Low

5. Test Coverage

  • Automated tests exist for the core business logicEven basic unit tests catch regressions during PHP version upgrades High
  • Critical user flows are covered by integration or end-to-end tests Medium
  • Tests run in CI and a failing test blocks deployment Medium
  • Code coverage is measured (even if not enforced at a threshold) Low

6. Documentation & Knowledge Transfer

  • Architecture is documented: what the system does, how it is structured, what depends on what High
  • Database schema is documented or self-describing (migrations, ER diagram) Medium
  • Non-obvious shell scripts are commented or explained in a runbook Medium
  • At least two team members understand the system well enough to make changes independently High
  • Credentials and secrets are managed in a secrets store (not hardcoded or in a text file on the server) High

7. Monitoring & Observability

  • Errors are logged and centralised (not only in server log files nobody reads) Medium
  • Alerting is in place for system failures and critical errors Medium
  • Monitoring agents (e.g. CheckMK) are compatible with the target platform and configuration is versioned Medium
  • Application performance baseline is known (response times, throughput) to validate post-migration Low

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If several High items are unchecked, your system needs stabilisation before a migration can begin. That is exactly what the migration audit engagement is designed for.

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