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Elastic Stack 7 : Install Elasticsearch2019/06/18

 
Install Full-Text search engine [Elasticsearch].
[1]
[2] Install and Run Elasticsearch.
[root@dlp ~]#
cat > /etc/yum.repos.d/elasticsearch.repo <<EOF
[elasticsearch-7.x]
name=Elasticsearch repository for 7.x packages
baseurl=https://artifacts.elastic.co/packages/7.x/yum
gpgcheck=1
gpgkey=https://artifacts.elastic.co/GPG-KEY-elasticsearch
enabled=1
autorefresh=1
type=rpm-md
EOF
[root@dlp ~]#
yum -y install elasticsearch
[root@dlp ~]#
systemctl start elasticsearch

[root@dlp ~]#
systemctl enable elasticsearch
# verify working

[root@dlp ~]#
curl http://127.0.0.1:9200

{
  "name" : "dlp.srv.world",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "fIQnFLWcTJCoC_AmELuJvA",
  "version" : {
    "number" : "7.1.1",
    "build_flavor" : "default",
    "build_type" : "rpm",
    "build_hash" : "7a013de",
    "build_date" : "2019-05-23T14:04:00.380842Z",
    "build_snapshot" : false,
    "lucene_version" : "8.0.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}
[3] This is the basic usage of Elasticsearch.
Create an Index first, it is like Database on RDB.
# show Index list ([pretty] means it shows JSON with human readable)

[root@dlp ~]#
curl http://127.0.0.1:9200/_aliases?pretty

{ }
# create Index

[root@dlp ~]#
curl -X PUT "http://127.0.0.1:9200/test_index"

{"acknowledged":true,"shards_acknowledged":true,"index":"test_index"}
# verify

[root@dlp ~]#
curl http://127.0.0.1:9200/_aliases?pretty

{
  "test_index" : {
    "aliases" : { }
  }
}
[root@dlp ~]#
curl http://127.0.0.1:9200/test_index/_settings?pretty

{
  "test_index" : {
    "settings" : {
      "index" : {
        "creation_date" : "1560476161429",
        "number_of_shards" : "1",
        "number_of_replicas" : "1",
        "uuid" : "u5nanOeOSCmGbSIlrqluZA",
        "version" : {
          "created" : "7010199"
        },
        "provided_name" : "test_index"
      }
    }
  }
}
[4] Define Mapping and insert test data.
Mapping defines structure of Index. If inserting data, Mapping will be defined automatically, but it's possible to define manually, of course.
# insert data

[root@dlp ~]#
curl -H "Content-Type: application/json" \
-X PUT "http://127.0.0.1:9200/test_index/doc01/1" -d '{
    "subject" : "Test Post No.1",
    "description" : "This is the initial post",
    "content" : "This is the test message for using Elasticsearch."
}'
{"_index":"test_index","_type":"doc01","_id":"1","_version":1,"result":"created","_shards":{"total":2,"successful":1,"failed":0},"_seq_no":0,"_primary_term":1}

# show Mapping

[root@dlp ~]#
curl "http://127.0.0.1:9200/test_index/_mapping/?pretty"

{
  "test_index" : {
    "mappings" : {
      "properties" : {
        "content" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "description" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        },
        "subject" : {
          "type" : "text",
          "fields" : {
            "keyword" : {
              "type" : "keyword",
              "ignore_above" : 256
            }
          }
        }
      }
    }
  }
}

# show data

[root@dlp ~]#
curl "http://127.0.0.1:9200/test_index/doc01/1?pretty"

{
  "_index" : "test_index",
  "_type" : "doc01",
  "_id" : "1",
  "_version" : 1,
  "_seq_no" : 0,
  "_primary_term" : 1,
  "found" : true,
  "_source" : {
    "subject" : "Test Post No.1",
    "description" : "This is the initial post",
    "content" : "This is the test message for using Elasticsearch."
  }
}

# search data

# example of Search conditions below means [description] field includes a word [initial]

[root@dlp ~]#
curl "http://127.0.0.1:9200/test_index/doc01/_search?q=description:initial&pretty=true"

{
  "took" : 156,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 0.2876821,
    "hits" : [
      {
        "_index" : "test_index",
        "_type" : "doc01",
        "_id" : "1",
        "_score" : 0.2876821,
        "_source" : {
          "subject" : "Test Post No.1",
          "description" : "This is the initial post",
          "content" : "This is the test message for using Elasticsearch."
        }
      }
    ]
  }
}
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