Introduction
The recent past has witnessed a significant transformation of software development life cycle. Architecting containerized and microservice based applications is a crucial and efficient approach to get rid of tightly coupled monolithic applications.
Containerization is a process of encapsulating applications into a unit that supports the environment to build, run, and deploy applications. It is a lightweight and portable environment for software components. Docker is a well-known platform to containerize an application by providing OS level virtualization and delivering software into bundles which is known as a container.
Application modernization and microservice-based architectures offer greater flexibility by dividing an application into smaller, independent services. This approach enhances stability and results in a loosely coupled architecture, in contrast to traditional monolithic applications.
Each service is designed based on a specific business logic and can interact with other services internally using API (Application programming interface) calls or different protocols. Hence, the design provides much more flexibility in terms of development, deployment, and balancing the load.
In this article, we will explore the fundamental components, benefits, challenges, and the architecture of containerized microservices, along with a bonus tip on creating the first containerized service using the Docker platform.
Components of containerized microservices
Services
Services are the individual components which are containerized with the specific business logic and capabilities. Each service is deployed individually using containers. Those services are loosely coupled and have capabilities to communicate with each other in a scalable fashion.
Containers
Containers are light weight, portable, and individually built units that provide an environment to run the application along with the dependencies. It provides runtime computing capabilities and flexibility to get it deployed at multiple platforms. There are various tools and platforms available such as Docker, Kubernetes, and Amazon ECS that take care of containerizing applications for deployment and scaling.
API Gateway
A common entry point for the requests to access the microservices architecture. API gateways take care of request routing, authorization, protocol configuration, and a common interface to the end consumers.
Load Balancer
Load balancer is a component responsible for scaling microservices by distributing the incoming requests from multiple sources. It helps keep minimum utilization of server resources by identifying service registries and configured routings.
Message or Events streaming
A reliable messaging system that facilitates asynchronous transmission between microservices. Its event-driven architecture design pattern enables scalable and robust message transmission. These components include two subcomponents called messages broker that takes care of communication across services and message queue that holds the events/messages temporarily and ensures successful delivery with fault tolerance.
Security
This component manages user identities, authentication, and authorization within the microservices architecture by identifying the roles and permitted actions of an incoming request. It ensures complete protection against the actions being performed using API endpoints. RBAC, API gateway security, Transport Later Security (TLS), Secured storage, Runtime protection, and Audit trails and logging are the major components of security.
Logging and Monitoring
A dedicated service that takes care of aggregating and storing the logs and data at a common repository helping monitoring, logging, and troubleshooting further. Monitoring is a process of harvesting the stored logs and app insights to check the system health, application insights, resource utilization, and performance.
Continuous Integration/Continuous Deployment (CI/CD)
CICD is an automated process for containerizing and building an app, testing, and deploying services. It enables quick and robust software delivery to the desired platform with minimal effort and with less time. This eliminates the basic human interference and risks while deploying the application.
Architectural Diagram
The microservices and containerization architecture diagram demonstrates a modern software architecture utilizing microservices and containerized solution to build scalable, robust, and efficient applications. It includes several components as shown below in the diagram.
This architecture contains four major components as below:
1. Consumer: The end user or system interacts with the service endpoints to exchange data between the client and server. The consumer is responsible for sending requests to the API gateway in a specified format, including required authentication and protocol details.
2. Container Host: It serves as a platform for executing services or code within a virtual operating system, containing all essential dependencies specific to the environment. The container host manages the entire lifecycle of an application, including initiating the service, handling over-the-air (OTA) updates, and terminating the application. It provides flexibility to manage the application behavior by specifying the environment variables and configuration parameters into the configuration file.
3. Microservices
Microservices is a collection of individual services designed for specific business objectives, interacting via configured internal endpoints or protocol on an event bus. These services are engineered to allow independent scaling of each component, minimizing disruption to others. In the event of a service failure, the impact is limited to specific service and business logic, ensuring resilience across the ecosystem. Troubleshooting becomes very easy with this modular approach.
In the diagram, four services are operational within a Docker host. These services communicate with each other through an event bus and are accessible to consumers via specific endpoints. Each service is equipped with its own unique business logic and database, resulting in consumer traffic being distributed accordingly. Scaling and load balancing can be independently managed for each service based on consumer traffic volume or request frequency.
4. Event Bus or Messaging channel
A microservice is a decentralized platform operating across multiple containers or virtual machines, necessitating interaction among various processes or services to fulfill specific business objectives. This communication method varies based on the nature of services, adapting to requirements and implementation. Possible protocols include HTTP, TCP, MQTT, AMQP, WebSocket, or others. The event bus plays a crucial role in enabling decoupled, asynchronous communication, and event-driven interactions within microservices architecture, fostering scalability, flexibility, and resilience in distributed systems.
Overall, container-based microservices provide significant advantages in terms of flexibility, scalability, resource efficiency, monitoring, and resilience, making them a preferred architectural approach for modern cloud-native applications.
Challenges and Considerations in containerized microservices
Containerized microservices provide much more flexibility and advantages though they also come with their own challenges and considerations. There are some key challenges that need consideration when choosing containerized microservices.
Architectural Complexity
Managing multiple services using containerized platforms like Docker and Kubernetes needs specific skills and expertise to handle it seamlessly. It might become complex to containerized multiple services with their own set of dependencies.
Networking and communication
Networking becomes challenging while communicating with the application, especially when the specific services keep scaling up and down depending on the requirements. Sometimes port forwarding, port mapping, volume mapping, and exposure of elements outside of a container become challenging.
Security
Containerized microservices offer additional security considerations, such as container vulnerabilities and network security. While deploying containerized code we might need to take care of coding practices, container image scanning, and access control to eliminate security risks.
Data management
Data management in containerized microservices environments can be challenging because each service might use distributed databases. Therefore, implementing data storage, backup, and recovery methods becomes a bottleneck to ensure data integrity.
Monitoring and troubleshooting
Monitoring and troubleshooting a containerized application demand specialized tools or expertise due to its encapsulation within a container on the host. Consequently, identifying logs, errors, or traces can be challenging, necessitating proper configuration of logging and monitoring features for effective troubleshooting of the application.
Cost Management
Containerized microservices environments may require additional costs associated with infrastructure, orchestration, monitoring, and troubleshooting tools. Considerations such as resource utilization, scaling methodologies, licensing, and troubleshooting tools must be factored in during the microservices’ development.
Continuous Integration/Continuous Deployment (CI/CD)
Containerized microservices can have multiple applications, posing challenges for CI/CD to ensure compatibility between images and source code. Proper versioning and compatibility measures must be implemented to address this complexity effectively.
Adopting containerized microservices might require additional skillful devops team to handle the deployment, potentially requiring additional resource allocation for adequate support.
Bonus Tip: “Hello World” of containerized app
Up to this point, we have grasped the concept of containerized microservice architecture. Here’s a bonus tip showcasing the orchestration of a .NET Core application within a Docker containerized platform.
1. Setup your .NET Core Web API project
You may use your convenient IDM to create .NET Core web API project but make sure your system has dotnet core pre-installed. If not, you can install it from the following link:
https://dotnet.microsoft.com/en-us/download
You may create a .NET Core web API from the template project, or you can create it using a command like argument as below by specifying the appropriate directory. The command will create a .NET Core web API project inside the FirstWebAPI directory.
2. Follow the project directory
Please follow the source code directory using cd command as below:
3. Dockerize Your .NET Core Web API Project
Create a Dockerfile at the root directory of your .NET Core Web API project, create a new file named “Dockerfile” with the following content:
This Dockerfile uses the .NET Core Docker images from Microsoft’s Container Registry to build and run your Web API project inside a docker container. You may use the appropriate .NET Core application base image depending on your need but here we have used .NET Core 5.0 as a base image.
The above commands take care of building and publishing your code using Dockerfile.
4. Build Y our Containerized .NET Core Web API
Build the Docker image: Run the following command in the terminal to build the Docker image for your .NET Core Web API project.
5. Run Your Containerized .NET Core Web API
Once the Docker image is built successfully, you can run the container using the following command:
This command runs the container in the detached mode (-d) and maps port 8080 on the host to port 80 inside the container. You will be able to access the API using localhost:8080 port because we have mapped container and host port using -p 8080:80 command.
You can test your API using https://localhost:8080/api/values depending on your controller’s name.
Bingo!! You have successfully containerized .NET Core application using Docker commands.
Conclusion
Containerized microservices provide a scalable, robust, and efficient way to build and deploy the software by orchestrating individual services within lightweight containers for better flexibility, agility, and resource utilization. However, this architectural design has certain challenges such as those which we have already gone through above. Adoption of containerized microservices needs careful planning, monitoring, troubleshooting skills, and tools. Though the benefits of containerized microservices are portability, scalability, and faster development time, they make them a superior choice for application modernization. With proper implementation and moderation, containerized microservices can be a boon in terms of organizational goals and requirements.
