Kashka

Elixir Kafka REST proxy client for Confluent REST Proxy.

Examples

Produce

{:ok, conn} = Kashka.Kafka.produce("http://localhost:8082/", "topic_name', [%{value: %{foo: "bar"}}])
:ok == Kashka.Kafka.close(conn)

See Kashka.Kafka.produce/4 for details.

Consume

defmodule TestModule do
  @behaviour Kashka.GenConsumer

  def init(conn, _args) do
    {:ok, conn, :state}
  end

  def handle_message_set(conn, :state, message_set) do
    IO.inspect(message_set)

    #[%{"key" => nil, "offset" => 0, "partition" => 0, "topic" => "test_name", "value" => %{"foo" => "bar"}}]

    {:ok, conn, :state}
  end
end

args = [
  url: "http://localhost:8082/",
  instance_id: "my",
  consumer_group: "consumer_group",
  topics: ["topic_name"],
  module: TestModule,
  delete_on_exists: false,
  retry_on_exists: true,
  consumer_opts: %{"auto.offset.reset": :earliest, "auto.commit.enable": true},
]

{:ok, pid} = GenConsumer.start_link(args)

See Kashka.GenConsumer for details.

More

See tests for more examples.

Kafka URL explanation

Kafka URL can be a String or a Keyword list. Keyword list can contain url, headers, fix_schema, fix_port, fix_host keys.

Examples:

[url: "http://127.0.0.1:8811", headers: [{"host", "smth.com"}]]

With fix_* keys:

[url: "http://127.0.0.1", fix_port: true, fix_schema: true, fix_host: true, headers: [{"host", "smth.com"}]]

fix_* keys used to automatically preprocess the URL returned from the consumer creation method.

For example if create_consumer method returns https://smth1.com:443/comsumers/group/instances/name as a base_uri, it is transformed to http://127.0.0.1:80/comsumers/group/instances/name with host header smth1.com.

It can be helpful while connecting to Kafka REST API through Nginx proxy.

protocols: option can be used for explicit specification of HTTP protocols negotiation with Kafka REST server. It can take the following values: :http1, :http2 or :any by default.

How to run tests

1. Run doker-compose up.
2. Run mix test in separate terminal.

Roadmap

• Make protection from endless loop in Kashka.Http.request.
• Correctly process other errors in Kashka.Http.request.