Domain 1: SDLC Automation

Key Concepts

• Continuous Integration (CI): The practice of merging all developers' working copies to a shared mainline several times a day.
• Continuous Delivery (CD): An extension of CI, ensuring that code can be released to production at any time.
• Infrastructure as Code (IaC): Managing and provisioning infrastructure through code instead of manual processes.
• Automated Testing: Using automated scripts to validate code changes, ensuring they meet quality standards.
• Version Control: Tracking and managing changes to software code, typically using tools like Git.

Detailed Explanation

Continuous Integration (CI)

CI involves regularly merging code changes into a central repository, after which automated builds and tests are run. This practice helps to detect errors quickly and locate them more easily.

Example: A team of developers working on a web application might use Jenkins to automatically build and test their code every time a new commit is made to the main branch.

Continuous Delivery (CD)

CD ensures that code changes are automatically built, tested, and prepared for a release to production. It allows for frequent, low-risk releases by automating the entire software release process.

Example: After passing all CI tests, the code is automatically packaged and deployed to a staging environment where further tests are run. If successful, it can be manually or automatically deployed to production.

Infrastructure as Code (IaC)

IaC treats infrastructure setup as software. This means using code to define, provision, and manage infrastructure, which can be versioned, tested, and reused.

Example: Using AWS CloudFormation to define an entire stack of resources (like EC2 instances, S3 buckets, and RDS databases) in a YAML or JSON template.

Resources:
  MyInstance:
    Type: 'AWS::EC2::Instance'
    Properties:
      ImageId: 'ami-0abcdef1234567890'
      InstanceType: t2.micro
      KeyName: MyKeyPair
    

Automated Testing

Automated testing involves using scripts to run tests on code changes, ensuring that new features or bug fixes do not introduce new issues. This can include unit tests, integration tests, and end-to-end tests.

Example: A Python application might use pytest to automatically run a suite of tests every time new code is pushed to the repository.

def test_addition():
    assert 1 + 1 == 2

def test_subtraction():
    assert 5 - 3 == 2
    

Version Control

Version control systems like Git allow developers to track changes to their code, collaborate with others, and revert to previous versions if necessary. This is crucial for maintaining code integrity and collaboration.

Example: A developer might use Git to create a new branch for a feature, make changes, and then merge those changes back into the main branch after review.

git checkout -b feature-branch
git add .
git commit -m "Implemented new feature"
git push origin feature-branch