Add Microsoft Azure support

[rmachielse]

Problem

Resolves #231. We would like to use ruby-openai with Microsoft Azure OpenAI, however its endpoints and authentication headers are slightly different, making it impossible currently to use this gem.

Solution

This PR adds a configuration setting api_type, which can be set to :azure, similar to how https://github.com/openai/openai-python supports Microsoft Azure.

Alternatives

I'm aware of the changes being worked on in #150, it might be possible to create a subclass of OpenAI::Client instead once this has been implemented. I'm happy to rebase and refactor this PR once this is merged.

Additional context

• Microsoft Azure currently only supports completions and embeddings, so these are the only endpoints implemented
• A Microsoft Azure account is needed to rerecord the tests with VCR, and the account needs to have OpenAI access. Currently a form needs to be submitted for this. Also, a deployment has to be created for every model used in the tests, and the deployment name has to match the model name. Documentation should probably be written for this.

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[rmachielse]

Now sure why circle is failing, it seems all the tests are missing the OPENAI_ACCESS_TOKEN

[steffansluis]

In cooperation with my colleague @rmachielse I've followed up on this. Initially I was looking at rebasing his changes, but I realized it would likely be easier to add the minimal required changes on top of main and slightly change the associated configuration changes.

In practice, the only differences that are really needed are to the uri and the headers, so I only ported those changes and added some tests for them. This works with the following (or similar) configuration (the example specifies config/initializers/openai.rb):

require 'openai'

OpenAI.configure do |config|
  config.access_token = Rails.application.config.app[:azure_openai_api_key]
  config.uri_base = "#{Rails.application.config.app[:azure_openai_uri]}/openai/deployments/gpt-35-turbo"
  config.api_type = :azure
  config.api_version = '2023-03-15-preview'
end

where azure_openai_uri is something like https://custom-domain.openai.azure.com.

In the process I realized there was an inconsistency with /es in the constructed URI, which I tried to fix with URI.join, however this resulted in some code constructions I didn't like so I ended up removing that part of the logic again. That unfortunately leads to the inconsistency where when using Azure, no trailing / is expected in the uri_base but when using the regular API a trailing / is expected and necessary.

I think the being able to use Azure outweighs this inconsistency so I went ahead with the changes like this. If you want I can see if I can come up with a clean way of addressing this. My suggestion would be to do it in a separate PR though, since the behavior was already problematic (no trailing / results in problems with the current logic) and being able to use the gem with Azure outweighs delaying this to fix it in my opinion.

Curious to hear what you think @alexrudall !

[rmachielse]

@alexrudall what do you think? These minimal changes should make it quite straight forward to at least allow usage of this gem with Microsoft Azure.

[timrwilliams]

I'd also like to see this merged. I think more and more people will be transitioning across to the Azure version, especially within corporate environments so this would be very helpful.

[IanRAnderson]

I'm also hoping for this functionality. Been using this Gem for developing a proof of concept for a new feature, but my organization is moving to Azure OpenAI for a variety of reasons, so the ability to continue to use this gem with Azure would be great.

[eichert12]

We're also moving to an Azure based version of OpenAI so would love to see Azure support in this gem.

[rmachielse]

@alexrudall seems like merging this PR would make a lot of people happy 😄 note that we simplified the implementation to the minimum necessary changes!

[alexrudall]

Released in v4.2!

Thanks for your patience on this all! @rmachielse and @steffansluis thanks a lot for your work. @steffansluis I fixed the trailing / issue. I think.