Use the CCR feature to migrate data

Procedure

1. Preparations
   Prepare a local cluster, a remote cluster, and a leader index.
2. Step 1: Connect clusters
   Connect the remote cluster to the local cluster.
3. Step 2: Add the remote cluster
   In the Kibana console of the local cluster, add the remote cluster.
4. Step 3: Configure CCR
   In the Kibana console of the local cluster, configure the leader index and a follower index.
5. Step 4: View migration results
   Insert data into the remote cluster. Then, verify the data migration on the local cluster.

Preparations

1. Prepare a local cluster and a remote cluster.
   For more information, see Create an Alibaba Cloud Elasticsearch cluster. The two clusters must be single-zone clusters and belong to the same virtual private cloud (VPC) and VSwitch. The versions of the two clusters must be the same (V6.7.0 or later).
2. Log on to the Kibana console of the remote cluster and create a leader index.
   Notice

   • When you create an index in an Elasticsearch cluster of V7.0 or earlier, you must enable the soft_deletes attribute. Otherwise, an error is reported.
   • If you want to migrate data in an existing index, you can call the reindex operation to enable the soft_deletes attribute.

   PUT myindex
   {
     "settings": {
       "index.soft_deletes.retention.operations": 1024,
       "index.soft_deletes.enabled": true
     }
   }

3. Disable the physical replication feature for the leader index.
   The physical replication feature is automatically enabled for indexes in Elasticsearch V6.7.0 clusters. Before you use CCR, you must disable the physical replication feature.
   1. Disable the index.

      POST myindex/_close

   2. Update the settings configuration of the index to disable the physical replication feature.

      PUT myindex/_settings
      {
      "index.replication.type" : null
      }

   3. Enable the index.

      POST myindex/_open

Step 1: Connect clusters

Configure the remote cluster to connect it to the local cluster. For more information, see Connect two Elasticsearch clusters. If the two clusters are connected, the information shown in the following figure appears.

Step 2: Add the remote cluster

1. Log on to the Kibana console of the local cluster.
   For more information, see Log on to the Kibana console.
2. In the left-side navigation pane, click Management.
3. In the Elasticsearch section, click Remote Clusters.
4. Click Add a remote cluster.
5. In the Add remote cluster section, configure the following parameters.
   

   • Name: the name of the remote cluster. The name must be unique.
   • Seed nodes: the nodes in the remote cluster. Specify each node in the format of Node IP address:9300. To obtain the IP addresses of nodes, log on to the Kibana console of the remote cluster and run the GET /_cat/nodes?v command on the Console tab of the Dev Tools page. The nodes you specify must include a dedicated master node of the remote cluster. We recommend that you specify multiple nodes. This way, if the dedicated master node fails, you can still use CCR.
     Notice During CCR, Kibana uses the IP addresses of data nodes to access clusters over TCP port 9300. HTTP port 9200 is not supported.
6. Click Save.
   The system then automatically connects to the remote cluster. If the connection is established, Connected appears.

Step 3: Configure CCR

1. Log on to the Kibana console of the local cluster. In the left-side navigation pane, click Management. In the Elasticsearch section of the page that appears, click Cross Cluster Replication.
2. On the Follower indices tab, click Create a follower index.
3. In the Add follower index section, configure the following parameters.
   

   Parameter	Description
   Remote cluster	Select the cluster you added in Step 2: Add the remote cluster.
   Leader index	The index whose data you want to migrate. In this example, the myindex index that is created in Preparations is used.
   Follower index	The index to which data is migrated. You must specify a unique name.

4. Click Create.
   After the follower index is created, the index is in the Active state.

Step 4: View migration results

1. Log on to the Kibana console of the remote cluster and insert data into the cluster.

   POST myindex/_doc/
   {
     "name":"Jack",
     "age":40
   }

2. Run the following command in the Kibana console of the local cluster to check whether the inserted data is migrated to the local cluster:

   GET myindex_follow/_search

   If the command is successfully executed, the result shown in the following figure is returned.

   The preceding figure shows that data in the leader index myindex of the remote cluster is migrated to the follower index myindex_follow of the local cluster.

   Notice The follower index is read-only. To write data to the follower index like to a common index, you must first convert it into a common index. For more information, see Cross-Datacenter Replication with Elasticsearch Cross-Cluster Replication.
3. Insert a data record into the remote cluster and check whether the data record is migrated to the local cluster in real time.

   POST myindex/_doc/
   {
     "name":"Pony",
     "age":50
   }

   Query the inserted data record in the local cluster immediately. The following figure shows the data record.

   The preceding figure shows that the CCR feature can implement real-time migration of incremental data.

   Note You can also call the API operations for this feature to perform related operations. For more information, see Cross-cluster replication APIs.

FAQ

Q: I can use port 9300 to add a remote cluster. Why is only port 9200 accessible when I use a domain name to access an Elasticsearch cluster?

A: Port 9300 is an open port. However, when you access a cluster over the Internet, Server Load Balancer (SLB) enables only port 9200 during port verification for security purposes. This will be adjusted in the future.