CST8915 Week 2: The Twelve-Factor Application

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Questions and Answers

What is the main purpose of the Twelve-Factor methodology?

To provide a framework for constructing applications optimized for cloud environments. (correct)

To offer a guide for developing traditional monolithic applications.

To simplify the process of building desktop applications.

To ensure applications are suitable for mobile devices.

What is emphasized in the Twelve-Factor methodology regarding deployment environments?

Portability across different environments is essential. (correct)

All environments must be identical.

No specific environments are required for deployment.

Code should only be deployed in production environments.

Which factor ensures that an application has a single codebase?

Factor 1: Code Base (correct)

Factor 4: Backing Services

Factor 2: Dependencies

Factor 3: Configuration

What should configuration values, such as database credentials, be stored in?

Environment variables Signup and view all the answers

Why is it important for dependencies to be explicitly declared?

To prevent the application from relying on the host for dependencies. Signup and view all the answers

What happens if multiple codebases are used for an application?

It is categorized as a distributed system. Signup and view all the answers

What is considered a backing service?

A service consumed over the network like a database Signup and view all the answers

What does the build stage transform in the deployment process?

A code repository into an executable bundle Signup and view all the answers

What does explicitly declaring dependencies typically involve?

Including dependencies in a dependency management file. Signup and view all the answers

What approach allows an application to switch between different instances of a backing service?

Changing configurations without code alterations Signup and view all the answers

What principle aids in rapidly deploying and scaling applications according to the Twelve-Factor methodology?

Declarative automation. Signup and view all the answers

Which of the following is NOT a pillar of cloud-native application design according to the Twelve-Factor methodology?

Extensive use of hardcoded paths. Signup and view all the answers

Why should dependencies be isolated?

To simplify deployment with containers Signup and view all the answers

What is the purpose of storing configuration separately from code?

To improve portability and security Signup and view all the answers

What does treating local services the same as remote services imply?

Configurations should allow switching without code modifications Signup and view all the answers

What is an appropriate description of the transformation from codebase to deploy?

Conversion through build, release, and run stages Signup and view all the answers

What is the primary characteristic of processes in the Twelve-Factor App methodology?

Processes should be stateless and share-nothing. Signup and view all the answers

Which service is NOT typically considered a stateful backing service in the Twelve-Factor App methodology?

Redis Signup and view all the answers

What does port binding encourage in the deployment of a Twelve-Factor App?

The application to directly bind to a port for handling requests. Signup and view all the answers

What is the primary benefit of favoring fast startup in application deployment?

To enhance scalability opportunities Signup and view all the answers

What scaling method is preferred in a Twelve-Factor App?

Horizontal scaling by running multiple instances of stateless processes. Signup and view all the answers

Why is it important to maintain development, staging, and production environments similar?

To prevent discrepancies and costly shortcuts Signup and view all the answers

How should logs be treated according to best practices?

As event streams output to stdout Signup and view all the answers

What should happen to service instances according to the disposability factor?

They should be disposable and allow for fast startup and graceful shutdown. Signup and view all the answers

What is a key characteristic of admin processes in an application environment?

They should be executed as one-off processes Signup and view all the answers

Which of the following statements about stateless processes is NOT true?

They store data permanently in memory for fast access. Signup and view all the answers

What can help ensure that the same execution environment is used across development and production?

Adopting containerization Signup and view all the answers

How do Twelve-Factor Apps manage robustness according to the disposability factor?

By allowing for quick termination and reinvention of instances. Signup and view all the answers

Which of the following is a benefit of the Twelve-Factor App's approach to port binding?

It enables the application to handle requests independently, without needing an external web server. Signup and view all the answers

What is the main reason to propagate log data to external systems like Azure Monitor?

To facilitate log processing and long-term archival Signup and view all the answers

Which factor helps avoid issues with divergent environments during admin tasks?

Executing tasks under the same codebase and environment Signup and view all the answers

What should applications primarily avoid concerning log management?

Managing log files directly by the app Signup and view all the answers

What does the build stage fetch and compile during the deployment process?

Vendor dependencies and binaries Signup and view all the answers

What must each release enforce according to best practices?

Strict separation across the build, release, and run stages Signup and view all the answers

What is the outcome of the release stage in the deployment process?

It combines the build with the deployment's current config Signup and view all the answers

What does it mean when it is stated that 'each release should be tagged with a unique ID'?

It simplifies the rollback process in case of failure Signup and view all the answers

Why is it impossible to make changes to the code at runtime?

There is no way to propagate those changes back to the build stage Signup and view all the answers

What is the function of the run stage in the deployment process?

To run the app in the execution environment Signup and view all the answers

In modern CI/CD systems, what principle is particularly fulfilled regarding releases?

Separation of build, release, and run stages Signup and view all the answers

What is a defining characteristic of a successful deployment process?

Strict adherence to a unique ID for each release Signup and view all the answers

Study Notes

Overview of Twelve-Factor Methodology

A cloud-native application framework emphasizing portability and declarative automation.
Ideal for constructing applications that can rapidly deploy and scale.
Serves as a foundational guideline for cloud-native app development.

Code Base

Must have a single codebase in version control (e.g., Git), supporting multiple deployment environments.
Each application maps to one codebase; multiple codebases indicate a distributed system.

Dependencies

All app dependencies should be explicitly declared in a management file (e.g., requirements.txt, package.json).
Applications must not depend on the host’s pre-installed libraries; package dependencies with the app.

Configurations

Store configuration settings (e.g., database credentials) in environment variables instead of hard-coding.
Enhances security and allows easy changes in configurations during runtime.

Backing Services

Treat any service utilized over a network (datastores, messaging systems) as attached resources.
Applications should operate with both local and remote services interchangeably without code modifications.

Build, Release, Run

Separate the processes of build (creating an executable bundle), release (combining build with config), and run (executing the app).
Unique IDs for releases facilitate strategic rollbacks if necessary.

Processes

Applications should be executed as stateless processes, relying on external stateful services for data storage.
This structure promotes scalability and reliability.

Port Binding

Applications should self-bind to ports, accepting incoming requests directly without requiring external web servers.
This encourages self-contained deployments.

Concurrency

Focus on horizontal scaling by running multiple stateless process instances instead of scaling vertically.
Enhances the cloud-native experience by facilitating easy scaling.

Disposability

Service instances must be easily disposable, ensuring minimal startup time and graceful shutdowns.
Containers, like Docker, naturally support these requirements.

Dev/Prod Parity

Maintain similar conditions across development, staging, and production environments to prevent inconsistencies.
Containers can help standardize execution environments.

Logging

Handle logs as event streams; applications should not manage log files directly.
Logs should be output to standard output and processed externally for analysis.

Admin Processes

Execute administrative tasks (e.g., database migrations) as one-off processes utilizing the same codebase and environment.
Ensures consistency and avoids discrepancies in task execution environments.

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Description

In this lesson, we will dive into the Twelve-Factor methodology for cloud-native development. Explore the core principles that guide the construction of robust, scalable cloud-based applications. Additionally, we will cover three extra factors relevant to modern applications, enhancing your understanding of contemporary cloud design.