Make services stateless where possible

Making services stateless wherever possible improves their scalability, availability, and resilience. Stateless services do not retain information about previous interactions, allowing servers to be replaced or scaled up and down without impacting the availability of the system. To achieve this, services should offload state to external storage systems like Amazon ElastiCache or Amazon DynamoDB, ensuring that there is no reliance on local disk or memory for retaining state between client requests.

Establish stateless champions in each team: Assign stateless champions within each workload team to oversee the design of stateless services. These champions ensure that services minimize the use of local state, offloading necessary information to external systems for better scalability and reliability.

Provide training on stateless service design: Train builder teams on best practices for designing stateless services, including offloading state to external systems and managing client sessions. Training should cover the use of services like Amazon ElastiCache or Amazon DynamoDB to store transient or session data and how to architect stateless services effectively. Proper training helps teams understand the benefits of stateless architecture and how to implement it successfully.

Develop stateless service guidelines and standards: Create clear guidelines for implementing stateless services. These guidelines should include best practices for offloading state, managing client sessions, and choosing appropriate storage solutions for different types of state information. Documented standards help ensure consistency across services, improving scalability, availability, and resilience.

Integrate stateless validation into CI/CD pipelines: Integrate validation checks into CI/CD pipelines to ensure that services are designed to be stateless wherever possible. Automated tests can verify that services do not rely on local state and that any state information is offloaded to appropriate storage systems, reducing the risk of service disruptions due to reliance on local storage.

Define automated guardrails for stateless design: Use automated tools to enforce stateless design principles across services. Tools like AWS Lambda, Amazon DynamoDB, and Amazon ElastiCache can be leveraged to ensure that state is managed externally rather than being retained locally. Automated guardrails help maintain compliance with stateless architecture best practices and improve system reliability.

Foster a culture of scalable, stateless architecture: Encourage builder teams to prioritize stateless design when developing services. Recognize and reward teams that effectively offload state and design stateless services, ensuring that systems can be scaled and replaced seamlessly. Open discussions about challenges related to state management can help create a culture that values stateless architecture and continuous improvement.

Conduct regular stateless reviews: Schedule regular reviews to evaluate the design of services and ensure that they are stateless wherever possible. These reviews should assess whether state is being offloaded to appropriate storage systems and whether services can function independently of local state. Regular reviews help maintain a focus on scalability and resilience in system design.

Leverage automation for consistent stateless service implementation: Use Infrastructure as Code (IaC) tools like AWS CloudFormation or AWS CDK to automate the deployment of stateless services. Automating these processes helps ensure consistency across environments and prevents state from being retained locally, maintaining scalability and resilience.

Provide dashboards for visibility into state management: Use dashboards to provide visibility into state management across services, including the use of external state storage and adherence to stateless design principles. Tools like Amazon CloudWatch and AWS X-Ray can help monitor how services handle state and identify any instances where local state may be improperly retained. Dashboards help builder teams proactively manage state and ensure services are stateless where possible.

Supporting Questions

• How do you ensure that builder teams design services to be stateless wherever possible?
• What mechanisms are in place to validate that state is being offloaded appropriately and not retained locally?
• How do you align service design practices with organizational standards for scalability, availability, and resilience?

Roles and Responsibilities

Stateless Champion (within Builder Team)

Responsibilities:

• Promote the design of stateless services to improve scalability and resilience.
• Guide the team in offloading state to external systems like Amazon ElastiCache or Amazon DynamoDB.

Application Developer

Responsibilities:

• Implement features in a stateless manner, ensuring that state is offloaded to appropriate storage solutions.
• Use automated tools to validate that services do not rely on local state during the development process.

Operations Team Member

Responsibilities:

• Assist builder teams with configuring state management systems to offload state and ensure stateless service design.
• Provide guidance and training to ensure alignment with best practices for stateless architecture.

Artifacts

Stateless Service Design Guidelines and Standards: A document outlining best practices for designing stateless services and offloading state to external systems.

Training Resources for Stateless Architecture: Hands-on labs, workshops, and documentation to help teams understand how to implement stateless services effectively.

Automated Stateless Validation Configurations: Scripts and configurations that help automate the validation of stateless service design across services and environments.

Relevant AWS Services

Training and Awareness Tools:

• AWS Skill Builder and AWS Well-Architected Labs: Resources for learning about designing stateless services, offloading state, and managing scalable architectures.
• AWS Trusted Advisor: Provides insights into workload configurations and recommendations for improving stateless architecture.

Stateless Implementation and Guardrails:

• Amazon ElastiCache: Provides in-memory caching to offload transient state, enabling stateless service design.
• Amazon DynamoDB: Stores session and application state, allowing services to remain stateless and scalable.
• AWS Lambda: Encourages stateless design by enforcing limits on execution duration and by not retaining any state between invocations.

Monitoring and Visibility Tools:

• Amazon CloudWatch: Tracks metrics related to state management, providing alerts for any improper use of local state.
• AWS X-Ray: Traces requests across services to verify that state is being managed externally and that services adhere to stateless principles.
• AWS CloudFormation: Codifies stateless service configurations to automate and standardize stateless service implementation across environments.