Can't override base_url to connect to local PubSub simulator

[jeffdeville]

GoogleApi.PubSub.V1.Connection
uses:
plug Tesla.Middleware.BaseUrl

instead of

Tesla.Middleware.BaseUrlFromConfig

As a result, it's impossible to try and direct commands to the local Pubsub simulator.

[chingor13]

Thanks, for the report.

It looks like BaseUrlFromConfig is being removed from Tesla so we'll need to find a different approach to allow configuring the base url.

[jeffdeville]

**Ok, NM. Just discovered swagger codegen, and it looks like this wasn't your decision to make. **

FWIW, Tesla, like Faraday that it's based on, introduced a ton of complexity for what looked like very little value. I can see where the idea came from, since just about all web frameworks do the same thing, but for an API client, there's really just 3 concerns. Where it's going, how it's secured, and how to format the data you need to send. A pipeline model is simply overkill.

Obviously I shouldn't really care what the underlying tech is here, and perhaps with this swagger code generator you have there's something it adds. But if not, I'd personally consider dropping it in favor of using the HTTPoison.Base macro instead. Short of that, it looks like tesla needs to be flexible enough to take it's various plug parameters as function definitions, and invoke them at runtime to allow things to be configurable.

[chingor13]

So yes, these libraries are all generated via Swagger Codegen. We do maintain our own templates here, so it's possible to swap out Tesla. Originally we picked Tesla because of multipart http posts and the ease of building requests.

We do have a goal to try and create a shared core library which could encapsulate the transport and try and simplify the generated code (and allow better configuration). We could either switch to HTTPoison or provide an equivalent BaseUrlFromConfig implementation.

Alternatively, we can look to simply swap out the middleware if we're ok locking the 0.x (the middleware is being removed in 1.0), but it could conflict in the future.

[teamon]

Disclaimer: I'm the author of tesla

BaseUrlFromConfig middleware was removed because it is not needed, you can achieve the same thing using:

plug Tesla.Middleware.BaseUrl, fetch_base_url_however_you_like()
# or
plug Tesla.Middleware.BaseUrl, Application.get_env(:google, :base_uri)

Middleware arguments are evaluated at runtime so everything will work just fine.

[florinpatrascu]

@teamon - I did that in my fork of the mustache templates, and it works very well, even closer to the initial intent of the author?! That of using a package specific env var. In my fork:

    Tesla.build_client([
      {Tesla.Middleware.BaseUrl, env_base_url()},
      {Tesla.Middleware.Headers, [{"Authorization", "Bearer #{token}"}]}
    ])

where the env_base_url is as simple as this:

  defp env_base_url() do
    Application.get_env(:{{#underscored}}{{packageName}}{{/underscored}}, :url, "{{{basePath}}}")
  end

@chingor13 - please observe the use of packageName rather than the appName, as the latter will result in something like: :google_cloud_pub/sub_api, an invalid Elixir Atom, of course.

[chingor13]

We just released new versions of the client libraries which includes the fix from #81