[grid][java]: dynamic grid re-fetch browser images if they were pruned during runtime

[VietND96]

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Description

Motivation and Context

Fix: SeleniumHQ/docker-selenium#1644

Steps to reproduce:

• launch Selenium Grid in dynamic grid mode (in our case, grid was deployed in docker stack, but this should not make a difference)
• spin up a browser node in dynamic grid and terminate it (image is persisted afterwards)
• perform docker image prune -a
• try to spin up the same browser node again

Expected behavior:

• browser node image is fetched again as it is missing locally
• browser node is launched successfully after image was fetched

Actual behavior:
Grid fails fatally trying to spin up a browser with the now missing image.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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Type

enhancement, bug_fix

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Description

• Added a new method getImage() in ContainerConfig to facilitate image retrieval.
• Enhanced the container creation process to automatically re-fetch browser images if they were pruned during runtime, addressing a fatal grid failure issue.
• Implemented a retry mechanism in the container creation process to handle cases where the Docker image is not found locally, by attempting to pull the image again before retrying.

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Changes walkthrough

	Relevant files
Enhancement	ContainerConfig.java Add Method to Retrieve Image from ContainerConfig                java/src/org/openqa/selenium/docker/ContainerConfig.java Added a method getImage() to retrieve the image from a ContainerConfig object. +4/-0
Bug_fix	CreateContainer.java Implement Image Re-fetch Logic for Docker Containers          java/src/org/openqa/selenium/docker/v1_41/CreateContainer.java Implemented a retry mechanism in apply method to handle "No such image" DockerException. Added a createContainer method to encapsulate container creation logic. Utilized PullImage to fetch the image if it's not found locally before retrying container creation. +15/-0

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[qodo-merge-pro]

PR Description updated to latest commit (079cc93)

• Copy walkthrough table to "Files Changed" Tab

[qodo-merge-pro]

PR Review

⏱️ Estimated effort to review [1-5]	2, because the changes are localized to specific methods within two classes, and the logic added is straightforward. The addition of a method to retrieve the image from a container configuration and the handling of a specific Docker exception to re-pull an image if it's not found are clear and concise modifications.
🧪 Relevant tests	No
🔍 Possible issues	Error Handling: The catch block in CreateContainer.apply only checks for the presence of "No such image" in the exception message. This could potentially lead to false positives if the DockerException message changes or includes "No such image" in a different context.
	Retry Logic: The retry mechanism after pulling the image does not have a limit. If the pull image operation fails silently (i.e., does not throw an exception but does not result in the image being available), this could lead to an infinite loop.
🔒 Security concerns	No

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[qodo-merge-pro]

PR Code Suggestions

Category	Suggestions
Best practice	Limit the visibility of the getImage method if it's for internal use. Consider making the getImage method package-private or protected if it's intended for internal use only, to adhere to the principle of least privilege. java/src/org/openqa/selenium/docker/ContainerConfig.java [87-89] -public Image getImage() { +Image getImage() { return this.image; }
	Use error codes for DockerException handling. Consider handling specific DockerException subtypes or error codes for more granular error handling instead of relying on message content. java/src/org/openqa/selenium/docker/v1_41/CreateContainer.java [59-62] -if (e.getMessage().contains("No such image")) { +if (e.getStatusCode() == HttpStatus.NOT_FOUND) { // Assuming DockerException includes a method to get HTTP status PullImage pullImage = new PullImage(client); pullImage.apply(Reference.parse(info.getImage().getName())); return createContainer(info); }
Maintainability	Refactor image pulling logic into a separate method. Extract the logic for pulling an image into a separate method to improve readability and maintainability. java/src/org/openqa/selenium/docker/v1_41/CreateContainer.java [56-66] try { return createContainer(info); } catch (DockerException e) { if (e.getMessage().contains("No such image")) { - PullImage pullImage = new PullImage(client); - pullImage.apply(Reference.parse(info.getImage().getName())); - return createContainer(info); + pullAndRetryCreateContainer(info); } else { throw e; } } +private Container pullAndRetryCreateContainer(ContainerConfig info) { + PullImage pullImage = new PullImage(client); + pullImage.apply(Reference.parse(info.getImage().getName())); + return createContainer(info); +} +
Enhancement	Add logging before image pull operations. Add logging before pulling an image to aid in debugging and monitoring the pull process. java/src/org/openqa/selenium/docker/v1_41/CreateContainer.java [60-61] +logger.info("Pulling image: " + info.getImage().getName()); PullImage pullImage = new PullImage(client); pullImage.apply(Reference.parse(info.getImage().getName()));
Possible issue	Prevent infinite loops in image pull retry logic. Ensure that the retry logic after pulling an image does not lead to an infinite loop in case of repeated failures. java/src/org/openqa/selenium/docker/v1_41/CreateContainer.java [59-62] if (e.getMessage().contains("No such image")) { PullImage pullImage = new PullImage(client); pullImage.apply(Reference.parse(info.getImage().getName())); - return createContainer(info); + try { + return createContainer(info); + } catch (DockerException retryException) { + logger.error("Failed to create container even after pulling image", retryException); + throw retryException; + } }

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[VietND96]

@diemol, could you please review this?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.72%. Comparing base (8d77159) to head (2608802).
Report is 6 commits behind head on trunk.

❗ Current head 2608802 differs from pull request most recent head c5c54e7. Consider uploading reports for the commit c5c54e7 to get more accurate results

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Additional details and impacted files

@@            Coverage Diff             @@
##            trunk   #13821      +/-   ##
==========================================
- Coverage   58.82%   58.72%   -0.10%     
==========================================
  Files          86       86              
  Lines        5272     5298      +26     
  Branches      219      226       +7     
==========================================
+ Hits         3101     3111      +10     
- Misses       1952     1961       +9     
- Partials      219      226       +7     

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