Elasticsearch ¶

Elasticsearch (63.8k ⭐) is a RESTful open-source search engine with an API and clients in many languages.

You can install version 8.7 using Docker as follows:

$ docker network create elastic
$ docker pull docker.elastic.co/elasticsearch/elasticsearch:8.7.0
$ docker run --name elasticsearch --net elastic -p 9200:9200 -p 9300:9300 -e "discovery.type=single-node" -t elasticsearch:8.7.0
# in another terminal
$ docker pull docker.elastic.co/kibana/kibana:8.7.0
$ docker run --name kibana --net elastic -p 5601:5601 docker.elastic.co/kibana/kibana:8.7.0

Note down the username/password and enrollment token. You can terminate both and start them again from the docker desktop app.

Navigate to the URL prompted by Kibana: http://localhost:5601/?code=xxxx or http://localhost:5601/ afterward. You can log in from there, and access the elasticsearch dashboard.

API notes

Elasticsearch will ask you to index the searchable documents first. Once you did, you will be able to search for them.

After setting up elasticsearch, you need to install elasticsearch-php:

$ composer require elasticsearch/elasticsearch

You can obtain the certificate using:

# output "http_ca.crt" in the current directory
$ docker cp elasticsearch:/usr/share/elasticsearch/config/certs/http_ca.crt .

The starter code would look like this:

$client = ClientBuilder::create()
    ->setHosts(['https://localhost:9200'])
    ->setBasicAuthentication('elastic', 'password here')
    ->setCABundle('path/to/http_ca.crt')
    ->build();

// version
$response = $client->info();
echo $response['version']['number'];

You can index a document as follows. The id is optional, while both the index and the body are up to you, and it can be JSON too.

$client->index([
    'id'=>'some_id_here',
    'index'=>'some_index_here',
    'body'=> [
        "xxx" => "I want to say 'Hello, World'!"
    ],
]);

To search for something, you can use query.match with xxx a key from the user-defined body.

$params = [
    'index' => 'same_index_as_before',
    'query' => [
        'match' => [
            'xxx' => 'hello world'
        ]
    ]
];
$response = $client->search($params);

echo "<pre>";
printf("Total docs: %d\n", $response['hits']['total']['value']);
printf("Max score : %.4f\n", $response['hits']['max_score']);
printf("Took      : %d ms\n", $response['took']);
print_r($response['hits']['hits']); // documents
echo "</pre>";

You can delete all documents in an index using:

$client->deleteByQuery([
    'index' => 'same_index_as_before',
    'body'=> [
        'query' => ['match_all' => (object)[]]
    ]
]);