# Elasticsearch
[](https://hex.pm/packages/elasticsearch)
[](https://semaphoreci.com/ir/elasticsearch-elixir)
[](https://coveralls.io/github/infinitered/elasticsearch-elixir?branch=master)
A simple, no-nonsense Elasticsearch library for Elixir. Highlights include:
- **No DSLs.** Interact directly with the `Elasticsearch` JSON API.
- **Zero-downtime index (re)building.** Via `Mix.Tasks.Elasticsearch.Build` task.
- **Dev Tools**. Helpers for runnig Elasticsearch as part of your supervision
tree during development.
## Installation
Add `elasticsearch` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:elasticsearch, "~> 0.1.0"}
]
end
```
## Configuration
See the annotated example configuration below.
```elixir
config :elasticsearch,
# The URL where Elasticsearch is hosted on your system
url: "http://localhost:9200", # or {:system, "ELASTICSEARCH_URL"}
# If your Elasticsearch cluster uses HTTP basic authentication,
# specify the username and password here:
username: "username", # or {:system, "ELASTICSEARCH_USERNAME"}
password: "password", # or {:system, "ELASTICSEARCH_PASSWORD"}
# When indexing data using the `mix elasticsearch.build` task,
# control the data ingestion rate by raising or lowering the number
# of items to send in each bulk request.
bulk_page_size: 5000,
# Likewise, wait a given period between posting pages to give
# Elasticsearch time to catch up.
bulk_wait_interval: 15_000, # 15 seconds
# If you want to mock the responses of the Elasticsearch JSON API
# for testing or other purposes, you can inject a different module
# here. It must implement the Elasticsearch.API behaviour.
api_module: Elasticsearch.API.HTTP,
# Customize the library used for JSON encoding/decoding.
json_library: Poison, # or Jason
# You should configure each index which you maintain in Elasticsearch here.
# This configuration will be read by the `mix elasticsearch.build` task,
# described below.
indexes: %{
# This is the base name of the Elasticsearch index. Each index will be
# built with a timestamp included in the name, like "posts-5902341238".
# It will then be aliased to "posts" for easy querying.
posts: %{
# This file describes the mappings and settings for your index. It will
# be posted as-is to Elasticsearch when you create your index, and
# therefore allows all the settings you could post directly.
settings: "priv/elasticsearch/posts.json",
# This store module must implement the Elasticsearch.Store
# behaviour. It will be used to fetch data for each source in each
# indexes' `sources` list, below:
store: MyApp.ElasticsearchStore,
# This is the list of data sources that should be used to populate this
# index. The `:store` module above will be passed each one of these
# sources for fetching.
#
# Each piece of data that is returned by the store must implement the
# Elasticsearch.Document protocol.
sources: [Post]
}
}
```
## Protocols & Behaviours
#### Elasticsearch.Store
Your app must provide a `Store` module, which will fetch data to upload to
Elasticsearch. This module must implement the `Elasticsearch.Store`
behaviour.
```elixir
defmodule MyApp.ElasticsearchStore do
@behaviour Elasticsearch.Store
@impl Elasticsearch.Store
def load(MyApp.Post, offset, limit) do
# Return MyApp.Posts, restricted by offset and limit
end
end
```
#### Elasticsearch.Document
Each result returned by your store must implement the `Elasticsearch.Document`
protocol.
```elixir
defimpl Elasticsearch.Document, for: MyApp.Post do
def id(post), do: post.id
def type(_post), do: "post"
def parent(_post), do: false
def encode(post) do
%{
title: post.title,
author: post.author
}
end
end
```
#### Elasticsearch.API
You can plug in a different module to make API requests, as long as it
implements the `Elasticsearch.API` behaviour.
This can be used in test mode, for example:
```elixir
# config/test.exs
config :elasticsearch,
api_module: MyApp.ElasticsearchMock
```
Your mock can then stub requests and responses from Elasticsearch.
```elixir
defmodule MyApp.ElasticsearchMock do
@behaviour Elasticsearch.API
def get("/posts/1", _headers, _opts) do
{:ok, %HTTPoison.Response{
status_code: 404,
body: %{
"status" => "not_found"
}
}}
end
end
```
## Indexing
#### Bulk
Use the `mix elasticsearch.build` task to build indexes using a zero-downtime,
hot-swap technique with Elasticsearch aliases.
```bash
# This will read the `indexes[posts]` configuration seen above, to build
# an index, `posts-123123123`, which will then be aliased to `posts`.
$ mix elasticsearch.build posts
```
See the docs on `Mix.Tasks.Elasticsearch.Build` and `Elasticsearch.Index`
for more details.
#### Individual Documents
Use `Elasticsearch.put_document/2` to upload a document to a particular index.
```elixir
# MyApp.Post must implement Elasticsearch.Document
Elasticsearch.put_document(%MyApp.Post{}, "index-name")
```
To remove documents, use `Elasticsearch.delete_document/2`:
```elixir
Elasticsearch.delete_document(%MyApp.Post{}, "index-name")
```
## Querying
You can query Elasticsearch the `post/2` function:
```elixir
# Raw query
Elasticsearch.post("/posts/post/_search", '{"query": {"match_all": {}}}')
# Using a map
Elasticsearch.post("/posts/post/_search", %{"query" => %{"match_all" => %{}}})
```
See the official Elasticsearch [documentation](https://www.elastic.co/guide/en/elasticsearch/reference/6.x/index.html)
for how to write queries.
## Dev Tools
This package provides two utilities for developing with Elasticsearch:
- `mix elasticsearch.install`: A mix task to install Elasticsearch and Kibana
to a folder of your choosing.
- `Elasticsearch.Executable`. Use this to start and stop Elasticsearch as part
of your supervision tree.
```elixir
children = [
worker(Elasticsearch.Executable, [
"Elasticsearch",
"./vendor/elasticsearch/bin/elasticsearch", # assuming elasticsearch is in your vendor/ dir
9200
]),
worker(Elasticsearch.Executable, [
"Kibana",
"./vendor/kibana/bin/kibana", # assuming kibana is in your vendor/ dir
5601
])
]
```
## Documentation
Run `mix docs` to generate local documentation.
## Contributing
To contribute code to this project, you'll need to:
1. Fork the repo
2. Clone your fork
3. Run `bin/setup`
4. Create a branch
5. Commit your changes
6. Open a PR
## Premium Support
[Infinite Red](https://infinite.red) offers premium support for this library and general web &
mobile app design/development services. Get in touch [here](https://infinite.red/contact) or email us at [hello@infinite.red](mailto:hello@infinite.red).
