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How to Use GitScrum for Legacy System Modernization?
How to use GitScrum for legacy system modernization?
Manage legacy modernization in GitScrum with migration-specific labels, track parallel systems, and document decisions in NoteVault. Use strangler pattern for incremental migration, coordinate feature parity tracking. Modernization teams with structured approach reduce migration risk by 60% [Source: Software Modernization Research 2024].
Modernization workflow:
- Assess - Understand legacy
- Plan - Migration strategy
- Build new - New system
- Migrate - Data + features
- Parallel - Run both
- Cutover - Switch traffic
- Decommission - Remove legacy
Modernization labels
| Label | Purpose |
|---|---|
| type-modernization | All modernization |
| mod-refactor | Refactoring |
| mod-migrate | Data migration |
| mod-replace | System replacement |
| mod-strangler | Strangler pattern |
| system-legacy | Legacy system |
| system-new | New system |
Modernization strategies
| Strategy | When to Use |
|---|---|
| Strangler | Incremental replacement |
| Lift and shift | Quick cloud migration |
| Rewrite | Fundamental change |
| Refactor | Improve existing |
| Wrap | API facade |
Modernization columns
| Column | Purpose |
|---|---|
| Assessment | Understanding legacy |
| Planning | Migration strategy |
| Development | Building new |
| Migration | Moving data/features |
| Validation | Testing parity |
| Cutover | Traffic switching |
NoteVault modernization docs
| Document | Content |
|---|---|
| Legacy analysis | Current state |
| Migration plan | Strategy, timeline |
| Feature matrix | Parity tracking |
| Risk register | Identified risks |
| Decision log | Architecture decisions |
| Rollback plan | If things go wrong |
Feature parity tracking
| Feature | Legacy | New | Status |
|---|---|---|---|
| User login | ✓ | ✓ | Migrated |
| Reporting | ✓ | In Progress | Developing |
| Admin | ✓ | Not Started | Planned |
Migration task template
## Migration: [feature/component]
### Legacy Analysis
- Current behavior: [description]
- Dependencies: [list]
- Data: [data involved]
### New Implementation
- Approach: [how to build]
- Changes: [differences from legacy]
### Migration Steps
- [ ] Build new feature
- [ ] Data migration
- [ ] Integration testing
- [ ] Traffic shifting (X%)
- [ ] Full cutover
- [ ] Legacy decommission
### Rollback Plan
[How to revert if issues]
### Parity Testing
- [ ] Functional parity
- [ ] Performance parity
- [ ] Data integrity
Strangler pattern workflow
| Phase | Action |
|---|---|
| Facade | Route through new |
| Build | New component |
| Migrate | Shift traffic |
| Monitor | Check for issues |
| Complete | Remove legacy |
Traffic shifting
| Phase | Traffic |
|---|---|
| Initial | 5% new |
| Expand | 25% new |
| Majority | 75% new |
| Full | 100% new |
Risk management
| Risk | Mitigation |
|---|---|
| Data loss | Backup, validation |
| Feature gap | Parity testing |
| Performance | Benchmarking |
| Downtime | Gradual cutover |
| Rollback needed | Documented plan |
Common modernization issues
| Issue | Solution |
|---|---|
| Unknown dependencies | Discovery phase |
| Data inconsistency | Validation tasks |
| Feature gaps | Parity matrix |
| Scope creep | Clear boundaries |
Modernization metrics
| Metric | Track |
|---|---|
| Features migrated | % complete |
| Traffic on new | % of requests |
| Issues found | Post-migration bugs |
| Timeline | Milestone tracking |
Decommission checklist
| Check | Verify |
|---|---|
| ☐ All traffic migrated | No legacy traffic |
| ☐ Data archived | If needed |
| ☐ Rollback window passed | Stable period |
| ☐ Stakeholder sign-off | Approval |
| ☐ Infrastructure removed | Clean up |