Got it to work.
We need to set the content-encoding to gzip
and then manually compress the responses like so
conn
|> put_resp_header("cache-control", "no-cache")
|> put_resp_header("connection", "keep-alive")
|> put_resp_header("content-type", "text/event-stream;")
|> put_resp_header("content-encoding", "gzip")
|> send_chunked(200)
And then compress the message manually and send them
defp send_chunk(conn, message) do
message = :zlib.gzip(message)
{:ok, conn} =
conn
|> prepare_sse()
|> chunk(message)
conn
end
