knox-site/docs/service_elasticsearch.md

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### Elasticsearch ###

Elasticsearch provides a REST API for communicating with Elasticsearch via JSON over HTTP. Elasticsearch uses X-Pack to do its own security (authentication and authorization). Therefore, the Knox Gateway is to forward the user credentials to Elasticsearch, and treats the Elasticsearch-authenticated user as "anonymous" to the backend service via a doas query param while Knox will authenticate to backend services as itself.

#### Gateway configuration ####

The Gateway can be configured for Elasticsearch by modifying the topology XML file and providing a new service XML file.

In the topology XML file, add the following new service named "ELASTICSEARCH" with the correct elasticsearch-rest-server hostname and port number (e.g., 9200):

     <service>
       <role>ELASTICSEARCH</role>
       <url>http://<elasticsearch-rest-server>:9200/</url>
       <name>elasticsearch</name>
     </service>

#### Elasticsearch via Knox Gateway ####

After adding the above to a topology, you can make a cURL request similar to the following structures:

##### 1.  Elasticsearch Node Root Query #####

    curl -i -k -u username:password -H "Accept: application/json"  -X GET  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch"

    or

    curl -i -k -u username:password -H "Accept: application/json"  -X GET  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/"

The quotation marks around the URL, can be single quotes or double quotes on both sides, and can also be omitted (Note: This is true for all other Elasticsearch queries via Knox). Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 16:36:34 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 356
     Server: Jetty(9.2.15.v20160210)
     
     {"name":"w0A80p0","cluster_name":"elasticsearch","cluster_uuid":"poU7j48pSpu5qQONr64HLQ","version":{"number":"6.2.4","build_hash":"ccec39f","build_date":"2018-04-12T20:37:28.497551Z","build_snapshot":false,"lucene_version":"7.2.1","minimum_wire_compatibility_version":"5.6.0","minimum_index_compatibility_version":"5.0.0"},"tagline":"You Know, for Search"}
    
##### 2.  Elasticsearch Index - Creation, Deletion, Refreshing and Data Operations - Writing, Updating and Retrieval #####

###### (1) Index Creation ######

    curl -i -k -u username:password -H "Content-Type: application/json"  -X PUT  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}"  -d '{
    "settings" : {
        "index" : {
            "number_of_shards" : {index-shards-number},
            "number_of_replicas" : {index-replicas-number}
        }
      }
    }'

Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 16:51:31 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 65
     Server: Jetty(9.2.15.v20160210)
     
     {"acknowledged":true,"shards_acknowledged":true,"index":"estest"}

###### (2) Index Data Writing ######

For adding a "Hello Joe Smith" document:

    curl -i -k -u username:password -H "Content-Type: application/json"  -X PUT  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}/{document-type-name}/{document-id}"  -d '{
        "title":"Hello Joe Smith" 
    }'

Below is an example response:

     HTTP/1.1 201 Created
     Date: Wed, 23 May 2018 17:00:17 GMT
     Location: /estest/greeting/1
     Content-Type: application/json; charset=UTF-8
     Content-Length: 158
     Server: Jetty(9.2.15.v20160210)
     
     {"_index":"estest","_type":"greeting","_id":"1","_version":1,"result":"created","_shards":{"total":1,"successful":1,"failed":0},"_seq_no":0,"_primary_term":1}

###### (3) Index Refreshing ######

    curl -i -k -u username:password  -X POST  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}/_refresh" 

Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 17:02:32 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 49
     Server: Jetty(9.2.15.v20160210)
     
     {"_shards":{"total":1,"successful":1,"failed":0}}

###### (4) Index Data Upgrading ######

For changing the Person Joe Smith to Tom Smith:

    curl -i -k -u username:password -H "Content-Type: application/json"  -X PUT  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}/{document-type-name}/{document-id}"  -d '{ 
    "title":"Hello Tom Smith" 
    }'

Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 17:09:59 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 158
     Server: Jetty(9.2.15.v20160210)
     
     {"_index":"estest","_type":"greeting","_id":"1","_version":2,"result":"updated","_shards":{"total":1,"successful":1,"failed":0},"_seq_no":1,"_primary_term":1}

###### (5) Index Data Retrieval or Search ######

For finding documents with "title":"Hello" in a specified document-type:

    curl -i -k -u username:password -H "Accept: application/json" -X GET  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}/{document-type-name}/ _search?pretty=true;q=title:Hello"

Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 17:13:08 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 244
     Server: Jetty(9.2.15.v20160210)
     
     {"took":0,"timed_out":false,"_shards":{"total":1,"successful":1,"skipped":0,"failed":0},"hits":{"total":1,"max_score":0.2876821,"hits":[{"_index":"estest","_type":"greeting","_id":"1","_score":0.2876821,"_source":{"title":"Hello Tom Smith"}}]}}

###### (6) Index Deleting ######

    curl -i -k -u username:password  -X DELETE  "https://{gateway-hostname}:{gateway-port}/gateway/{topology-name}/elasticsearch/{index-name}"

Below is an example response:

     HTTP/1.1 200 OK
     Date: Wed, 23 May 2018 17:20:19 GMT
     Content-Type: application/json; charset=UTF-8
     Content-Length: 21
     Server: Jetty(9.2.15.v20160210)
     
     {"acknowledged":true}