8.7 Testing

Testing the containers can be split into 2 categories:

  • functional - making sure that code works

  • business - making sure that it does what is supposed to do.

Functional testing

Functional testing is the process of testing the functionality of a software application. It is a type of black-box testing that is performed to verify that the application under test is working as expected. Functional testing involves testing the application against the functional requirements/specifications.

Validating the structure and configuration of container images is an essential step to ensure that they are built correctly and securely. Here are some methods and tools you can use to validate your container images:

  1. Lint Dockerfile: Use a linter tool like hadolint to check your Dockerfile for best practices and common issues. This can help you catch potential problems before building the image.

  2. Analyze image layers: Use tools like dive or Docker Desktop to inspect the layers of your container image. This can help you identify unnecessary files or dependencies that could be removed to reduce the image size.

  3. Check for vulnerabilities: Scan your container image for known vulnerabilities using tools like clair, trivy, or anchore. These tools can help you identify and fix security issues in your images.

  4. Verify image metadata: Inspect the image metadata, such as labels, environment variables, and exposed ports, using the docker inspect command. This can help you verify that the image is configured correctly.

  5. Test image configurations: Test the configurations of your container image by running it with various environment variables, command-line arguments, or configuration files. This can help you ensure that your container behaves correctly under different settings.

  6. Use configuration management tools: Tools like Ansible, Chef, or Puppet can help you manage your container configurations and ensure that they are consistent across your environment.

  7. Validate container runtime settings: Test your container with different runtime settings, such as resource limits, network configurations, and storage options, to ensure that it works correctly in various environments.

  8. Test container orchestration: If you’re using an orchestration platform like Kubernetes, make sure to validate your container configurations in that environment. Use tools like docker, kubectl, helm, or kustomize to manage and test your container configurations.

  9. Implement continuous integration (CI): Set up a CI pipeline to automatically build, test, and validate your container images whenever changes are made to the codebase or configurations. Tools like Jenkins, GitLab CI/CD, and GitHub Actions can help automate the process.

  10. Monitor and log container behavior: Use monitoring and logging tools like Prometheus, Grafana, Elasticsearch, or Fluentd to track the behavior of your containers in production. This can help you identify and address any issues related to the structure and configuration of your container images.

Business testing

Business testing is the process of testing the business requirements of a software application. It is a type of black-box testing that is performed to verify that the application under test is working as expected. Business testing involves testing the application against the business requirements/specifications.