Snap

Snap is an Elasticsearch client. It provides a flexible, performant API on top of your Elasticsearch cluster, supporting high level features like versioned index management, while also providing a convenient interface into low level operations.

See the full API docs.

Features

• Versioned index management with zero-downtime hotswapping (compatible with elasticsearch)
• Streaming bulk operations
• Connection pooling
• Telemetry events

Installation

The package can be installed by adding snap to your list of dependencies in mix.exs:

def deps do
  [
    {:snap, "~> 0.6"},
    {:finch, "~> 0.8"}, # By default, Snap uses Finch to make HTTP requests
  ]
end

Snap supports Elixir 1.11 or later.

Usage

Implement your own cluster module, similar to an Ecto.Repo:

defmodule MyApp.Cluster do
  use Snap.Cluster, otp_app: :my_app
end

Configure it:

config :my_app, MyApp.Cluster,
  url: "http://localhost:9200",
  username: "my_username",
  password: "my_password"

Then wire it into your application supervisor:

def start(_type, _args) do
  children = [
    {MyApp.Cluster, []}
  ]

  opts = [strategy: :one_for_one, name: MyApp.Supervisor]
  Supervisor.start_link(children, opts)
end

Now you can perform operations on your cluster:

{:ok, %{"count" => count}} = MyApp.Cluster.get("/my-index/_count")

Testing

If you want to test your app that uses this library, but don't want to have integration tests with a Elasticsearch instance running in you local dev environment, you can mock the responses using a custom HTTP client adapter.

Supposing you are using mox, you can do something like this:

# in test_helper.exs
Mox.defmock(HTTPClientMock, for: Snap.HTTPClient)
Mox.stub(HTTPClientMock, :child_spec, fn _config -> :skip end)

# in config/test.exs
config :my_app, MyApp.Cluster, http_client_adapter: HTTPClientMock

# in a test file
Mox.expect(HTTPClientMock, :request, fn _cluster, _method, _url, _headers, _body, _opts
  body = "{}" # valid json
  {:ok, %Snap.HTTPClient.Response{status: 200, headers: [], body: body}}
end)

See the API documentation for more advanced features.