Faraday: How to use retry with POST method

Hi @yusefu, apologies for the lack of documentation, this is something we're trying to address in v1.0.
In the meantime, let me help with your issue. Basically the retry_if is an option you can pass exactly how you pass max: 5, exceptions: [BadRequest, NotFound, ServerError, Faraday::Error::ConnectionFailed]. The only difference is that retry_if must be a function (either a lambda or a proc.
If you're unfamiliar with those, I would suggest to go with a proc, which can be instantiated with Proc.new { ... } or with the multi-line Proc.new do ... end.

So if you want to use retry_if your example would become something like:

def my_connection(my_api_endpoint)
  # This is optional, I've added the @connections memoized variable to avoid
  # re-creating the connection every time. Not sure it's applicable to your case
  # but consider it as it might improve performances
  @connections ||= []
  @connections[my_api_endpoint] ||= Faraday.new(url: my_api_endpoint) do |faraday|
    faraday.request  :retry, max: 5, exceptions:
      [BadRequest, NotFound, ServerError, Faraday::Error::ConnectionFailed],
      retry_if: Proc.new do |env, exception|
        # your implementation goes here...
      end
     faraday.response :logger
     faraday.adapter  Faraday.default_adapter
     faraday.options[:open_timeout] = 10
  end
end

However, if your only aim is to add :post to the list of retry methods, you can also use the methods option added on that PR you linked:

def my_connection(my_api_endpoint)
  # This is optional, I've added the @connections memoized variable to avoid
  # re-creating the connection every time. Not sure it's applicable to your case
  # but consider it as it might improve performances
  @connections ||= []
  @connections[my_api_endpoint] ||= Faraday.new(url: my_api_endpoint) do |faraday|
    faraday.request  :retry, max: 5, exceptions:
      [BadRequest, NotFound, ServerError, Faraday::Error::ConnectionFailed],
      methods: Faraday::Request::Retry::IDEMPOTENT_METHODS + [:post]
     faraday.response :logger
     faraday.adapter  Faraday.default_adapter
     faraday.options[:open_timeout] = 10
  end
end

Please let me know if this helps 😄

The connections instance gave a TypeError.

expected MyAPI::BadRequest, got #<TypeError: {:req=>{}, :res=>nil, :headers=>nil, :reason_phrase=>nil}> with backtrace:

But with the simple add of post to IDEMPOTENT_METHODS the retry is now possible.
Thank you very much @iMacTia 🙏 it did work.

Thanks for the feedback @yusefu and sorry for the TypeError.
I think the issue is that @connections should be a hash, not an array, my bad!

@connections ||= {}

Anyway, happy to know your issue is now solved 👍!