Monolith to Microservices: 5 Strategies, Challenges and Solutions

To understand the transition from Monolith to Microservices, we first need to define these two terms. A monolith refers to a traditional software application where all the functionality resides in a single codebase. This model, while simple, can become increasingly complex and difficult to manage as the application grows.

Microservices, on the other hand, break down the monolithic architecture into smaller, independent services, each with its own codebase and responsibility. In this model, different teams can work on different services, allowing for faster development and deployment cycles.

Migrating an application from a monolithic architecture to a microservices architecture can be complex and challenging, but the benefits often outweigh the drawbacks. We’ll review these benefits, common strategies for migrating from monolith to microservices, and touch on key challenges in the process and possible solutions.

Monolith to Microservices: Key Benefits 

Scalability

Scaling a monolithic application can be a daunting task. Since all components are interwoven, you often have to scale the entire application, even if only a single component needs more resources. This leads to unnecessary resource consumption and cost overhead.

With microservices, you can scale individual services based on their demand. This granular scalability allows you to optimize resource utilization and cost. It also enables you to handle increased loads proficiently, contributing to a better user experience.

Polyglot Architecture

In a monolithic architecture, you’re generally stuck with the technology stack you initially chose. This can hinder innovation and make it difficult to adopt new technologies.

Microservices offer the freedom to choose the best technology stack for each service (this is known as a polyglot architecture, because it can “speak many languages”). This can foster innovation and allow you to leverage the latest technologies to improve your applications. It also means teams can work in parallel, using the tools and languages they’re most comfortable with, increasing productivity and morale.

Resilience

In a monolithic application, a failure in one part of the application can bring the entire system down. It is possible to make monolithic applications fault tolerant, but this is complex and requires intensive maintenance.

Microservices, by their very nature, are isolated and independent. A failure in one service doesn’t affect the functioning of others. Microservices can also be scaled more easily, which enables redundancy. This increases the overall resilience of the application, leading to higher availability and a better user experience.

Optimized Resource Utilization

In a monolithic application, resources are often over-allocated to ensure that increased demand can be met. This leads to wastage and inefficient resource utilization.

Microservices, on the other hand, allow for more efficient resource utilization. You can allocate resources based on the demand of individual services, reducing wastage and optimizing utilization. This can lead to significant cost savings over the long term.

5 Strategies for Migrating from Monolith to Microservices 

Here are some of the common strategies to make the move from monolith to microservices.

1. Incremental Refactoring

Incremental refactoring involves gradually transforming a monolithic system into a microservices architecture. This strategy allows you to progressively decompose a monolith into microservices, reducing the risk of business disruption.

With incremental refactoring, you can start by identifying the parts of the monolith that are most suitable for becoming independent microservices. These could be functionalities that are relatively isolated from the rest of the system or those that would benefit most from the advantages offered by microservices, such as scalability and speed of deployment.

2. Strangler Pattern

The strangler pattern is a strategy that involves gradually replacing parts of a monolithic application with microservices while the monolith is still running. This pattern is inspired by the strangler fig tree, which grows around other trees and gradually replaces them.

The strangler pattern allows you to gradually introduce microservices into your system without disrupting the functioning of the monolith. This approach helps reduce risk and allows for a smoother transition process.

3. Decomposing by Business Capability

This strategy involves breaking down a monolith into microservices based on business functionalities. This strategy aligns the technical components of your system with your business objectives, making it easier to manage and evolve your system in response to business needs.

When decomposing by business capability, it is important to ensure that each microservice is responsible for a single business capability. This helps maintain the independence of microservices and reduces the complexity of the system.

4. Anticorruption Layer (ACL)

The anticorruption layer (ACL) is a strategy used to ensure that the transition from monolith to microservices does not corrupt the business logic of your system. The ACL acts as a barrier between the monolith and the microservices, converting data and requests between the two systems.

Using an ACL can help ensure that the transition process does not affect the integrity of your system’s business logic. This is particularly important when dealing with legacy systems, which often lack the necessary documentation to fully understand their business logic.

5. Domain-Driven Design (DDD)

Domain-driven design (DDD) is a software development approach that focuses on understanding the business domain and using this understanding to guide the design and development of software. In the context of transitioning from monolith to microservices, DDD can be used to identify the boundaries of microservices and to ensure that the transition process aligns with business goals.

DDD involves creating a model of the business domain and using this model to design the microservices. This approach helps ensure that each microservice corresponds to a specific part of the business domain, which can help ensure that the microservices architecture fully supports your business objectives.

Tips from the expert

Itiel Shwartz

Co-Founder & CTO

Itiel is the CTO and co-founder of Komodor. He’s a big believer in dev empowerment and moving fast, has worked at eBay, Forter and Rookout (as the founding engineer). Itiel is a backend and infra developer turned “DevOps”, an avid public speaker that loves talking about things such as cloud infrastructure, Kubernetes, Python, observability, and R&D culture.

In my experience, here are tips that can help you transition from monolith to microservices effectively:

Start with a Comprehensive Assessment

Begin with a detailed assessment of your monolithic application. Identify tightly coupled components, potential service boundaries, and areas with the most significant impact on performance or maintenance.

Prioritize Independent and High-Impact Services

Prioritize the decomposition of services that are relatively independent and have a high impact on scalability or performance. This allows for quicker wins and demonstrates the value of microservices.

Implement API Gateway for Unified Access

Use an API Gateway to manage and route requests to your microservices. This provides a single entry point for clients, handles cross-cutting concerns like authentication and rate limiting, and simplifies the transition process.

Adopt Event-Driven Architecture

Consider using an event-driven architecture to facilitate communication between microservices. This decouples services and allows them to react to changes asynchronously, improving scalability and resilience.

Utilize Circuit Breakers for Fault Tolerance

Implement circuit breakers to handle failures gracefully. Tools like Hystrix can help detect failures and prevent cascading issues by isolating problematic services.

Challenges of the Transition from Monolith to Microservices Architecture and How to Solve Them 

Data Management

In a monolithic system, all components typically share the same database. However, in a microservices architecture, each service ideally has its own database to ensure decoupling. This makes it necessary to overhaul the data architecture of an application.

Solution: Implement a carefully planned data migration strategy that may involve breaking down the monolithic database into smaller, service-specific databases. Make use of database refactoring techniques and adopt data synchronization methods where necessary. Consider implementing API endpoints to handle cross-service data interactions, and look into techniques such as eventual consistency to manage data across services.

Service Communication

In a monolithic system, components usually communicate through method calls within the same codebase. When moving to a microservices architecture, you must determine how services will interact with each other, as they are now separate entities running in different environments.

Solution: Utilize well-defined APIs for service-to-service communication. Make use of service orchestration or choreography patterns to manage complex interactions. Protocols like HTTP/REST or messaging queues can be used for asynchronous communication. Implement service discovery mechanisms to dynamically locate services within the system.

Deployment and Monitoring

Deploying and monitoring a microservices-based application involves more complexity compared to a monolithic one. Each microservice may have its own deployment pipeline, and monitoring multiple services can be a challenge due to the distributed nature of the system.

Solution: Use containerization technologies like Docker and orchestration tools like Kubernetes to standardize deployment and scaling. Implement centralized logging and monitoring solutions to keep track of the entire system’s health. Automate as much of the deployment and monitoring processes as possible to reduce manual error and increase efficiency.

Learn more in our detailed guide to microservices deployment (coming soon)

Updating Legacy Systems

Many organizations that seek to transition to microservices are working with older, legacy systems that might be poorly documented and hard to understand. The transition could be risky if not managed properly.

Solution: Conduct a thorough codebase and documentation review to understand how the legacy system functions. Make use of strategies like incremental refactoring and the strangler pattern to gradually transition to a microservices architecture. Where documentation is lacking, consider implementing reverse-engineering techniques or an Anti Corruption Layer to understand legacy system functionality and prevent unexpected behavior.

Learn more in our detailed guide to monolith to microservices migration (coming soon)

Managing and Monitoring Microservices Applications with Komodor

Komodor is a dev-first Kubernetes operations and reliability management platform. It excels in providing a simplified and unified UI through which you can manage the daily tasks associated with Kubernetes clusters. At its core, the platform gives you a real-time, high-level view of your cluster’s health, configurations, and resource utilization. This abstraction is particularly useful for routine tasks like rolling out updates, scaling applications, and managing resources. You can easily identify bottlenecks, underutilized nodes, or configuration drift, and then make informed decisions without needing to sift through YAML files or execute a dozen kubectl commands.

Beyond just observation, Komodor integrates with your existing CI/CD pipelines and configuration management tools to make routine tasks more seamless. The platform offers a streamlined way to enact changes, such as scaling deployments or updating configurations, directly through its interface. It can even auto-detect and integrate with CD tools like Argo or Flux to support a GitOps approach! Komodor’s “app-centric” approach to Kubernetes management is a game-changer for daily operational tasks, making it easier for both seasoned DevOps engineers and those new to Kubernetes to keep their clusters running smoothly, and their applications maintaining high-availability.

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