Add Azure OpenAI provider, take 2

[gjtorikian]

What this does

This is a continuation of @oxaroky02's excellent PR (#279); in fact, I cherry-picked most of their commits. As mentioned, this adds the Azure OpenAI provider:

context =  RubyLLM.context do |config|
  config.azure_openai_api_base = ENV.fetch('AZURE_OPENAI_URI')
  config.azure_openai_api_key = ENV.fetch('AZURE_OPENAI_API_KEY', nil)
  config.azure_openai_api_version = ENV.fetch('AZURE_OPENAI_API_VER', nil)
  config.default_model = ENV.fetch('AZURE_OPENAI_MODEL') || 'gpt-4o'
end

chat = context.chat(
  provider: :azure_openai,
  model: ENV.fetch('AZURE_OPENAI_MODEL') || 'gpt-4o',
  assume_model_exists: true)

chat.ask "Hello!"

A lot of changes occurred since the PR was first opened, and, as I didn't have access to make changes to the original branch, I decided to just open a new PR with the fixes necessary to speed things up and push this addition over the line. Those changes include:

• migrating the provider from a module to a class
• removing extraneous files
• adding VCR cassettes for the new provider

The biggest "gotcha" is that Azure OpenAI does not have all the models that "regular" OpenAI has; as well, the endpoints for some of the features are different. So there's some inheritance from the OpenAI provider going on, and some patches necessary to get this working with Azure.

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation
• Performance improvement

Scope check

• I read the Contributing Guide
• This aligns with RubyLLM's focus on LLM communication
• This isn't application-specific logic that belongs in user code
• This benefits most users, not just my specific use case

Quality check

• I ran overcommit --install and all hooks pass
• I tested my changes thoroughly
  • For provider changes: Re-recorded VCR cassettes with bundle exec rake vcr:record[provider_name]
  • All tests pass: bundle exec rspec
• I updated documentation if needed
• I didn't modify auto-generated files manually (models.json, aliases.json)

API changes

• Breaking change
• New public methods/classes
• Changed method signatures
• No API changes

Related issues

Closes #15

[oxaroky02]

@gjtorikian, thank you for doing this. 🙏

[gjtorikian]

@crmne bump for review on this? I’m not keen to keep fixing merge conflicts if there’s no interest.

context: MSFT gives out 100k in free OpenAI credits to qualifying startups so I suspect there are a lot of people using their Azure tie-in (myself included) that would benefit from an official way to integrate, rather than monkey patching.

[MirkoMignini]

@crmne bump for review on this? I’m not keen to keep fixing merge conflicts if there’s no interest.

context: MSFT gives out 100k in free OpenAI credits to qualifying startups so I suspect there are a lot of people using their Azure tie-in (myself included) that would benefit from an official way to integrate, rather than monkey patching.

Thanks for your work on this, hope will be merged soon