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AWS Solutions Architect · Lesson

Operational Excellence and Security Pillars

Apply IaC, small reversible changes, and runbooks for operations; use the principle of least privilege, data protection, and incident response for security.

The Well-Architected Framework

The AWS Well-Architected Framework provides a set of best practices and guiding questions to help architects build secure, high-performing, resilient, and efficient cloud infrastructure. It is organised into six pillars: Operational Excellence, Security, Reliability, Performance Efficiency, Cost Optimisation, and Sustainability. This lesson covers the first two pillars. The SAA-C03 exam frequently asks which pillar a given design principle belongs to, so understanding each pillar clearly is essential.

# Six Pillars of the Well-Architected Framework:
# 1. Operational Excellence
# 2. Security
# 3. Reliability
# 4. Performance Efficiency
# 5. Cost Optimisation
# 6. Sustainability

# Each pillar has:
# - Design principles (practices to adopt)
# - Questions (evaluation criteria)
# - Best practices (specific implementation guidance)

Operational Excellence: Core Design Principles

The Operational Excellence pillar focuses on running and monitoring systems to deliver business value and continually improving processes. Key design principles: Perform operations as code — use CloudFormation, CDK, or Systems Manager to automate infrastructure and operational tasks. Make frequent, small, reversible changes — deploy in small increments that can be rolled back. Anticipate failure — design for and practice recovering from failure. Learn from operational failures — conduct post-mortems and improve.

# CloudFormation: operations as code
aws cloudformation create-stack \
  --stack-name my-app-stack \
  --template-url s3://my-bucket/template.yaml \
  --parameters ParameterKey=Env,ParameterValue=prod

# Rollback on failure is automatic
# Small, reversible change: deploy a new AMI
aws autoscaling start-instance-refresh \
  --auto-scaling-group-name my-asg \
  --preferences MinHealthyPercentage=90

All lessons in this course

  1. Operational Excellence and Security Pillars
  2. Reliability and Performance Efficiency Pillars
  3. Cost Optimisation and Sustainability Pillars
  4. Well-Architected Tool and Review Process
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