Private registry error handling.

[thavaahariharangit]

What are you trying to accomplish?

Currently, if the private registry returns an error, Dependabot falls back to the global registry to fetch dependencies. Based on the discussion with the team, in this PR, I am now throwing an error and informing the customer that there was an issue accessing the configured registry.

Anything you want to highlight for special attention from reviewers?

The PR is not yet complete.

1. I still need to discuss with the team regarding which error should be thrown.
2. RSpec tests have not been implemented yet.
3. I need to have a discussion with @jakecoffman since he has implemented the fallback logic.

How will you know you've accomplished your goal?

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[randhircs]

As mentioned , separate pull request for complete fix. I approve it.

[abdulapopoola]

can you dig into where known_registries is set? It should only be a private registry if a private registry is set

[thavaahariharangit]

Yes it is,

However, I see that a fallback logic has been implemented by @jakecoffman (see line 102). That's why I requested his review on these changes.

[jakecoffman]

I need to have a discussion with @jakecoffman since he has implemented the fallback logic.

I'm not sure how you came to that conclusion. The change I have in this section of code is #5840 where I wrote:

When a global registry is present in one of these files, Dependabot shouldn't make calls to registry.npmjs.org.

So I am in agreement that a private registry failure shouldn't end up calling the public registry. Maybe you should also have the other rescue in this block raise a DependencyFileNotResolvable too.