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How to Create a Microservices Migration Project Plan

Create a microservices migration project plan with a Gantt chart. Track domain decomposition, service extraction, API gateway setup, and cutover milestones. Free online tool.

How to Create a Microservices Migration Project Plan

The Problem: Monolith-to-Microservices Migrations Take Years Without a Plan

Migrating from a monolith to microservices is one of the most complex engineering undertakings a team can attempt. It's not a single project—it's a program spanning domain decomposition, service extraction, inter-service communication design, data migration, deployment infrastructure changes, and organizational restructuring (Conway's Law applies).

Without a microservices migration project plan, teams make two common mistakes: they try to extract too many services too fast, or they work on different domains simultaneously and create integration chaos. Both paths lead to a codebase that's neither a clean monolith nor functioning microservices—the worst of both worlds.

A Gantt chart with explicit service extraction sequencing, infrastructure phases, and feature freeze gates prevents this. gantt-chart.io is free and requires no account.

Prerequisites

  • Domain model: Is the domain model clearly defined? (Domain-Driven Design boundary analysis)
  • Team structure: Will teams own individual services? (Conway's Law alignment)
  • Current monolith: What is the data layer? Shared database that needs to be decomposed?
  • Infrastructure readiness: Is Kubernetes/container orchestration in place?
  • Service mesh decision: Istio, Linkerd, or simple REST/gRPC with manual service discovery?
  • Migration approach: Strangler fig (recommended) or big bang?

Step-by-Step Instructions

Step 1: Set Up the Timeline

  1. Open gantt-chart.io
  2. Title the chart: Microservices Migration - [System Name]
  3. Plan 6–18 months depending on monolith size
  4. Use service extraction phases as the core structure
  5. Use Week view for infrastructure phases; Month for full program view

Step 2: Define the Five Migration Phases

  1. Domain Analysis — identify service boundaries, decompose domain model
  2. Infrastructure Foundation — container orchestration, service mesh, CI/CD
  3. Service Extraction (Waves) — extract services one bounded context at a time
  4. Data Decomposition — break up shared database per service
  5. Monolith Decommission — retire remaining monolith code

Step 3: Domain Analysis (Month 1)

  1. Event storming workshop — Week 1-2
  2. Bounded context identification — Week 2-3
  3. Service dependency map — Week 3
  4. Data ownership mapping — Week 3-4
  5. Extraction sequence prioritized — Week 4
  6. Domain model approved — Week 4 (milestone)

Extract services in this order: leaf services (fewest dependencies) first, core domain services last.

Step 4: Infrastructure Foundation (Month 1-3)

  1. Container strategy defined (Docker) — Month 1
  2. Kubernetes cluster provisioned — Month 1-2
  3. CI/CD pipeline for microservices — Month 2
  4. API gateway configured — Month 2
  5. Service discovery and load balancing — Month 2-3
  6. Observability: distributed tracing (Jaeger/Zipkin) — Month 2-3
  7. Centralized logging — Month 3
  8. Infrastructure complete — Month 3 (milestone)

Step 5: Service Extraction Wave 1 (Month 3-6)

Target leaf services—those with few dependencies on other domains:

Service 1: Notification Service

  1. Extract notification logic into service — Month 3, Week 1-3
  2. Publish async events from monolith — Month 3, Week 3-4
  3. Route notifications through new service — Month 4, Week 1
  4. Notification service live — Month 4 (milestone)

Service 2: Authentication Service

  1. Extract auth logic — Month 4, Week 1-3
  2. Issue JWTs from new service — Month 4, Week 3-4
  3. Monolith validates tokens from new service — Month 5, Week 1
  4. Auth service live — Month 5 (milestone)

Service 3: [Next leaf service]

  1. Continue pattern — Month 5-6

Step 6: Service Extraction Wave 2 (Month 6-10)

Target core domain services. These are harder—they involve data decomposition:

Service: [Core Domain A]

  1. Extract service code — Month 6-7
  2. Dual-write to monolith DB and service DB — Month 7
  3. Data validation: both DBs consistent — Month 7-8
  4. Switch reads to service DB — Month 8
  5. Remove dual-write — Month 9
  6. Service fully independent — Month 9 (milestone)

Step 7: Data Decomposition (Running Throughout Wave 2)

  1. Identify shared tables in monolith DB — Month 5
  2. Schema decomposition design per service — Month 6
  3. Create new database per service — Month 7
  4. Dual-write phase per service — Month 7-9
  5. Cut reads to service database — Month 9-11
  6. Shared tables removed from monolith DB — Month 12

Step 8: Monolith Decommission (Month 12-18)

As each service is extracted:

  1. Remove extracted code from monolith — after each service cutover
  2. Remove shared DB tables — after data migration complete
  3. Monolith down to API gateway + glue code only — Month 14
  4. Final monolith code retired — Month 18 (milestone)

Warning: The Distributed Monolith Anti-Pattern

The most common microservices failure is creating a "distributed monolith": services that are deployed independently but are tightly coupled through synchronous API calls and shared databases. Signs you've built a distributed monolith:

  • Services always deployed together
  • One service failure brings down others
  • Database is still shared

Every service in your migration plan should be deployable independently, own its data, and communicate asynchronously where possible.

Common Mistakes

Extracting too many services simultaneously. Extract one service at a time. Once it's stable in production, extract the next. Parallel extraction creates integration chaos.

Shared database at the start. Starting with microservices that share a monolith database defeats the purpose. Plan data decomposition as a first-class workstream.

Build your microservices migration plan at gantt-chart.io—free, no account required.