1. Overview (Project Background)

DoAllTech is a B2B SaaS company supporting digital transformation in the construction industry,
providing various solutions including project management, access control, and drawing management.

With increasing customer numbers and SaaS business expansion, the existing legacy architecture centered on Windows-based EC2 faced limitations in
service scalability, deployment speed, and cost efficiency.

Accordingly, DoAllTech pursued a project aimed at securing business agility, multi-tenancy security, and operational efficiency simultaneously through
not just a simple infrastructure migration, but a transition to a container-based SaaS architecture and service modernization (App Modernization).

2. Challenge (Problem Definition)

Prior to the project, DoAllTech faced the following business and technical challenges.

Business Perspective

• Slow service deployment speed taking days to reflect customer requirements and improve features

• Concerns about service stability degradation due to traffic spikes when user numbers increase

• Need to secure multi-tenancy structure and revenue scalability for SaaS model transition

Technical Perspective

• Limitations in scaling and deployment due to monolithic .NET application structure

• Operational complexity due to lack of IaC and automation

• Absence of modern architecture suitable for organic service integration and expansion

• Need for security, authentication, and isolation models in multi-tenant environments

These limitations became factors hindering continuous growth and SaaS business expansion.

3. Solution (Resolution Approach)

DoAllTech, together with Megazone Cloud, established a phased SaaS transition strategy and
reorganized services centered on AWS-based container architecture and DevOps automation.

1. Architecture Diagnosis and Redesign

• Architecture design considering reliability, scalability, and cost efficiency through AWS Well-Architected Review (WAR)

• Reorganization of existing EC2-based services from an App Modernization perspective

2. Container-Based Service Transition

• Transition of existing Windows/.NET workloads to Linux container-based ECS architecture

• Separation of monolithic structure into function-specific microservices

• Implementation of multi-tenant authentication and tenant isolation model based on AWS Cognito

3. CI/CD and IaC Enhancement

• Integration of GitHub Actions with AWS CodePipeline/CodeDeploy

• Application of ECS-based Blue-Green zero-downtime deployment

• Codification of ECS, ECR, ALB, and CI/CD resources through Terraform-based IaC

4. Cost Optimization Operations Strategy

• Selection of ECS over EKS to reduce operational complexity and labor costs

• Container density optimization using M7i-flex and ENI Trunking

• Continuous cost reduction through flexible staging environment operations and build cache strategy

Through this, operational stability and service innovation speed were secured simultaneously.

4. Result (Achievements)

Through SaaS transition and infrastructure modernization, DoAllTech achieved the following results.

• Improved service response speed and customer satisfaction

• 60% reduction in service deployment cycle
  (Manual deployment → Automatic deployment within 5 minutes after Git push)

• Reduced infrastructure operations burden on development team to secure environment focused on product innovation

• Secured scalable SaaS architecture based on multi-tenancy

• Established foundation for future growth through cost-effective and stable operations structure

Based on this, DoAllTech is actively expanding its B2B SaaS business.