Adding Nodes to Clusters

reference

Nodes are added to clusters with the POST /controller/addNode HTTP method and URI.

HTTP method and URI

POST /controller/addNode

Description

This adds a server node to the cluster. Every Operational Insights node runs exactly the Data Service (kv) and the Analytics Service (cbas), and the added node is given both. The services parameter can therefore be omitted; if it is specified, its value must be kv,cbas.

Operational Insights provides heightened security for adding nodes to clusters: a node that is to be added must itself be provisioned with conformant certificates before addition can be successfully performed. The new node is now always added over an encrypted connection. See Adding and Joining New Nodes.

In consequence, a server to be added can be prefixed with the scheme https://, and/or can be suffixed with the port 18091): if no scheme or port is specified, https:// and 18091 are used as defaults. The scheme http:// cannot be used; nor can the port 8091, since addition takes place only over a secure connection.

To further increase cluster security, restrictions can be placed on node-addition, based on the establishment of node-naming conventions. Only nodes whose names correspond to at least one of the stipulated conventions can be added. For information, see Restrict Node-Addition.

Validating Node Certificates

The node-name must be correctly identified in the node certificate as a Subject Alternative Name. If such identification is not correctly configured, failure may occur when attempting to add or join the node to a cluster. For information, see Certificates.

Curl Syntax

curl -u [admin]:[password]
  http://[localhost]:8091/controller/addNode
  -d hostname=[IPaddress]
  -d user=[username]
  -d password=[password]
  -d services=kv,cbas

Note that the administrative username and password must be specified. If the new node has not yet been provisioned, placeholder names must be provided.

Responses

Success gives 200 OK, and returns an object of the form {"otpNode":"ns_1@ip-address-of-added-node"}, to confirm that the node has been added. Specifying an unknown service gives 400 Bad Request, and an object of the form ["Unknown services: [\"unknown-service-name\"]"]. Specifying any list of services other than kv,cbas gives 400 Bad Request, and an error of the form Invalid services list. Expected [kv,cbas], got […]. If the node to be added has already been provisioned, and its administrative credentials are not properly specified, 400 Bad Request is given, and an object is returned of the form ["Prepare join failed. Authentication failed. Verify username and password."]

If the IP address of the new node cannot be reached, 400 Bad Request is given, and an object is returned of the form ["Failed to reach erlang port mapper at node \"ip-address-of-new-node\". Error: ehostunreach"]. If the IP address of the host cluster is not accurately specified, or otherwise cannot be reached, the request times out, giving Empty reply from server. Failure to authenticate with the cluster gives 401 Unauthorized.

If an attempt is made to specify a node to be added with the scheme http:// and/or the suffix 8091, the request fails with 400 Bad Request, and the error-message http is prohibited due to security reasons, please use https.

When failure results from certificate checking (see Certificates), a message of the following form is provided: Attention: Prepare join failed. Unable to validate certificate on host: 127.0.0.1. Please make sure the certificate on this host contains host name '127.0.0.1' in Subject Alternative Name. Refer to Couchbase docs for more info on how to create node certificates.

Example

The following example adds a server node, 10.143.190.103, to the cluster at 10.143.190.101:8091, establishing the Data and Analytics Services on the new node. The IP address for the new server and its administrative credentials are provided.

curl -v -X POST -u Administrator:password \
http://10.143.190.101:8091/controller/addNode \
-d 'hostname=https://10.143.190.103' \
-d 'user=Administrator' \
-d 'password=password' \
-d 'services=kv,cbas'

If successful, Operational Insights responds as follows, identifying the node that has been added:

{"otpNode":"ns_1@10.143.190.103"}

Subsequent to addition, the node must be rebalanced into the cluster. See Rebalancing the Cluster.

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