Table of Contents
What Does Container Image Mean?
A container image is a packaged file that contains all the components needed to create a container instance. It includes the application code, libraries, system tools, runtime, and configuration files.
When an image is executed by a container runtime, it becomes a live container. Because the image is immutable, containers started from the same image always behave consistently across environments.
Why Container Images Matter
Container images are fundamental to cloud-native workflows because they:
- Guarantee consistency by ensuring every container starts from the same source.
- Enable portability across development laptops, CI/CD pipelines, and production clusters.
- Support versioning and traceability through registries that store and tag images.
- Simplify automation, making it possible to rapidly spin up reproducible test and application environments.
Real-World Examples and Use Cases
- Application delivery: Teams build images and push them to container registries (e.g., Docker Hub, Amazon ECR).
- Test executors: Packaging JMeter, Postman, or Cypress executors into images for Testkube.
- CI/CD workflows: Automatically building, tagging, and deploying new images on every commit.
- Security scanning: Validating images for vulnerabilities before deployment.
How Container Images Work with Testkube
Testkube relies on container images to package test executors. Each supported testing tool—whether it’s load testing with JMeter, API testing with Postman, or UI testing with Cypress—can be containerized into an image.
Testkube then:
- Pulls images from registries into Kubernetes clusters.
- Runs executors in isolated pods based on those images.
- Ensures consistency so tests run reliably regardless of cluster or environment.
- Supports customization, letting teams create their own container images for specialized executors.