Elasticsearch Connector as Source in Flink

Question

I used Elasticsearch Connector as a Sink to insert data into Elasticsearch (see : https://ci.apache.org/projects/flink/flink-docs-release-1.7/dev/connectors/elasticsearch.html ).

But, I did not found any connector to get data from Elasticsearch as source.

Is there any connector or example to use Elasticsearch documents as source in a Flink pipline?

Regards,

Ali

Answer 1

I don't know of an explicit ES source for Flink. I did see one user talking about using elasticsearch-hadoop as a HadoopInputFormat with Flink, but I don't know if that worked for them (see their code ).

Answer 2

I finaly defined a simple read from ElasticSearch function

    public static class ElasticsearchFunction
        extends ProcessFunction<MetricMeasurement, MetricPrediction> {

    public ElasticsearchFunction() throws UnknownHostException {
        client = new PreBuiltTransportClient(settings)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("YOUR_IP"), PORT_NUMBER));
    }

    @Override
    public void processElement(MetricMeasurement in, Context context, Collector<MetricPrediction> out) throws Exception {
        MetricPrediction metricPrediction = new MetricPrediction();

        metricPrediction.setMetricId(in.getMetricId());
        metricPrediction.setGroupId(in.getGroupId());
        metricPrediction.setBucket(in.getBucket());

        // Get the metric measurement from Elasticsearch
        SearchResponse response = client.prepareSearch("YOUR_INDEX_NAME")
                .setSearchType(SearchType.DFS_QUERY_THEN_FETCH)
                .setQuery(QueryBuilders.termQuery("YOUR_TERM", in.getMetricId()))   // Query
                .setPostFilter(QueryBuilders.rangeQuery("value").from(0L).to(50L))     // Filter
                .setFrom(0).setSize(1).setExplain(true)
                .get();

        SearchHit[] results = response.getHits().getHits();
        for(SearchHit hit : results){
            String sourceAsString = hit.getSourceAsString();
            if (sourceAsString != null) {
                ObjectMapper mapper = new ObjectMapper();
                MetricMeasurement obj = mapper.readValue(sourceAsString, MetricMeasurement.class);
                obj.getMetricId();
                metricPrediction.setPredictionValue(obj.getValue());
            }
        }
        out.collect(metricPrediction);
    }
}

Answer 3

Hadoop Compatibility + Elasticsearch Hadoop

https://github.com/cclient/flink-connector-elasticsearch-source