Mint adapter does not support HTTP2 push

[ZsoltMaslanyi]

Hi guys,

This is a feature request that I can't take on on my own.

The Mint adapter does not support HTTP2 push messages and I haven't found a way to disable it through the adapter configuration.

The following arguments were given to anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3:
# 1
{:push_promise, #Reference<0.1726172914.1690042371.196731>,
 #Reference<0.1726172914.1690042371.196749>,
 [
   {":method", "GET"},
   {":path", "/assets/index.css?1583114754"},
   {":scheme", "https"},
   {":authority", "remoteok.io"},
   {"user-agent", "mint/1.0.0"}
 ]}
# 2
%{}

[teamon]

Please share an example code, these is little I can do with the given information.

I'm also not sure if this is a feature, or a bug. Please clarify.

[ZsoltMaslanyi]

Hi @teamon , thanks for taking the time to check this!

Sorry if it wasn't obvious from the description, here's the example code:

defmodule TeslaClient do
  use Tesla
  adapter(Tesla.Adapter.Mint)

  def get_example_http2_site() do
    get("https://remoteok.io")
  end
end

TeslaClient.get_example_http2_site()

The error message is the same as the original post I wrote.
The Mint adapter's reduce_responses/3 gets called with :push_promise to push down content on the connection, but the response is not handled by the adapter.

Re for if it's a feature request or a bug - I'd go with feature request, but you'll be the judge.
Tesla does have a Mint adapter, but it fails to work on any HTTP2 sites.

[teamon]

Confirmed:

iex(5)> Tesla.get(client, "https://remoteok.com")
** (FunctionClauseError) no function clause matching in anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3    
    
    The following arguments were given to anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3:
    
        # 1
        {:push_promise, #Reference<0.179896103.3862429701.90397>,
         #Reference<0.179896103.3862429701.90400>,
         [
           {":method", "GET"},
           {":path", "/global.css?1639217940"},
           {":scheme", "https"},
           {":authority", "remoteok.com"},
           {"user-agent", "mint/1.3.0"}
         ]}
    
        # 2
        %{}
    
    (tesla 1.4.3) lib/tesla/adapter/mint.ex:328: anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3
    (elixir 1.12.3) lib/enum.ex:2385: Enum."-reduce/3-lists^foldl/2-0-"/3
    (tesla 1.4.3) lib/tesla/adapter/mint.ex:298: Tesla.Adapter.Mint.receive_packet/4
    (tesla 1.4.3) lib/tesla/adapter/mint.ex:258: Tesla.Adapter.Mint.receive_responses/4
    (tesla 1.4.3) lib/tesla/adapter/mint.ex:197: Tesla.Adapter.Mint.format_response/3
    (tesla 1.4.3) lib/tesla/adapter/mint.ex:59: Tesla.Adapter.Mint.call/2

[yordis]

I tried to replicate this: https://gist.github.com/yordis/ea7226110cc578e4372845e3dffd92d3#file-elixir-tesla-tesla-pull-591-livemd

But it seems to be working just fine.