January 19, 2025
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This section describes how to connect the Ruby SDK to a Couchbase cluster. It contains best practices as well as information on TLS/SSL and other advanced connection options.

Connecting to a Cluster

A connection to a Couchbase Server cluster is represented by a Cluster object. A Cluster provides access to Buckets, Scopes, and Collections, as well as various Couchbase services and management interfaces. The simplest way to create a Cluster object is to call Cluster.connect() with a connection string, username, and password:

ruby
require "couchbase" include Couchbase # to avoid repeating module name options = Cluster::ClusterOptions.new options.authenticate("Administrator", "password") cluster = Cluster.connect("couchbase://localhost", options)
If you are connecting to a version of Couchbase Server older than 6.5, it will be more efficient if the addresses are those of data (KV) nodes. You will in any case, with 6.0 and earlier, need to open a Bucket instance before connecting to any other HTTP services (such as Query or Search).

In a production environment, your connection string should include the addresses of multiple server nodes in case some are currently unavailable. Multiple addresses may be specified in a connection string by delimiting them with commas:

options = Couchbase::ClusterOptions.new
options.authenticator = Couchbase::PasswordAuthenticator.new("Administrator", "password")
cluster = Cluster.connect("couchbase://192.168.56.101,192.168.56.102", options)
You don’t need to include the address of every node in the cluster. The client fetches the full address list from the first node it is able to contact.

Connection Strings

A Couchbase connection string is a comma-delimited list of IP addresses and/or hostnames, optionally followed by a list of parameters.

The parameter list is just like the query component of a URI; name-value pairs have an equals sign (=) separating the name and value, with an ampersand (&) between each pair. Just as in a URI, the first parameter is prefixed by a question mark (?).

Simple connection string with one seed node
couchbase://127.0.0.1
Connection string with two seed nodes
couchbase://nodeA.example.com,nodeB.example.com
Connection string with two parameters
couchbases://127.0.0.1?enable_dns_srv=false&query_timeout=10000

The full list of recognized parameters is in the table below.

A connection string must be prefixed by either couchbase:// or couchbases://.

Connection Lifecycle

Most of the high-level classes in the Ruby SDK are designed to be safe for concurrent use by multiple threads.

We recommend creating a single Cluster instance when your application starts up, and sharing this instance throughout your application. If you know at startup time which buckets, scopes, and collections your application will use, we recommend obtaining them from the Cluster at startup time and sharing those instances throughout your application as well.

Alternate Addresses and Custom Ports

If your Couchbase Server cluster is running in a containerized, port mapped, or otherwise NATed environment like Docker or Kubernetes, a client running outside that environment may need additional information in order to connect the cluster. Both the client and server require special configuration in this case.

On the server side, each server node must be configured to advertise its external address as well as any custom port mapping. This is done with the setting-alternate-address CLI command introduced in Couchbase Server 6.5. A node configured in this way will advertise two addresses: one for connecting from the same network, and another for connecting from an external network. This can also be set and retrieved through the REST API.

On the client side, the externally visible ports must be used when connecting. If the external ports are not the default, you can specify custom ports explicitly in the connection string.

options = Couchbase::ClusterOptions.new
options.authenticator = Couchbase::PasswordAuthenticator.new("Administrator", "password")
cluster = Cluster.connect("couchbase://192.168.42.101:12000,192.168.42.102:12002", options)
In a deployment that uses multi-dimensional scaling, a custom KV port is only applicable for nodes running the KV service. A custom manager port may be specified regardless of which services are running on the node.

In many cases the client is able to automatically select the correct set of addresses to use when connecting to a cluster that advertises multiple addresses. If the detection heuristic fails in your environment, you can override it by setting the network client setting to default if the client and server are on the same network, or`external` if they’re on different networks.

Any TLS certificates must be set up at the point where the connections are being made.

Secure Connections

Couchbase Server Enterprise Edition and Couchbase Capella support full encryption of client-side traffic using Transport Layer Security (TLS). This includes key-value type operations, queries, and configuration communication. Make sure you have the Enterprise Edition of Couchbase Server, or a Couchbase Capella account, before proceeding with configuring encryption on the client side.

For TLS certificate verification the SDK uses the following CA certificates:

  • The certificates in the Mozilla Root CA bundle (bundled with the SDK as of 3.4.3 and obtained from curl).

  • The certificates in OpenSSL’s default CA certificate store (as of SDK 3.4.0).

  • The self-signed root certificate that is used to sign the Couchbase Capella certificates (bundled with the SDK as of 3.3.0).

The OpenSSL defaults can be overridden using the SSL_CERT_DIR and SSL_CERT_FILE environment variables. The SSL_CERT_DIR variable is used to set a specific directory in which the client should look for individual certificate files, whereas the SSL_CERT_FILE environment variable is used to point to a single file containing one or more certificates. More information can be found in the relevant OpenSSL documentation.

Loading the Mozilla certificates can be disabled by setting the disable_mozilla_ca_certificates parameter in the connection string.

The Couchbase++ core’s metadata provide information about where OpenSSL’s default certificate store is located, which version of the Mozilla CA certificate store was bundled, and other useful details. You can get the relevant metadata using the following command:

console
$ ruby -r couchbase -e 'pp Couchbase::BUILD_INFO[:cxx_client].select{|k, _| k =~ /^(mozilla|openssl_default)/}'
ruby
{:mozilla_ca_bundle_date=>"Tue Jan 10 04:12:06 2023 GMT", :mozilla_ca_bundle_embedded=>true, :mozilla_ca_bundle_sha256=>"fb1ecd641d0a02c01bc9036d513cb658bbda62a75e246bedbc01764560a639f0", :mozilla_ca_bundle_size=>137, :openssl_default_cert_dir=>"/etc/pki/tls/certs", :openssl_default_cert_dir_env=>"SSL_CERT_DIR", :openssl_default_cert_file=>"/etc/pki/tls/cert.pem", :openssl_default_cert_file_env=>"SSL_CERT_FILE"}

With debug-level logging enabled, if the Mozilla certificates have been loaded, a message with the information about the version of the Mozilla CA certificate store will be outputted. For example:

console
loading 137 CA certificates from Mozilla bundle. Update date: "Tue Jan 10 04:12:06 2023 GMT", SHA256: "fb1ecd641d0a02c01bc9036d513cb658bbda62a75e246bedbc01764560a639f0"

The Ruby SDK bundles Capella’s standard root certificate by default. This means you don’t need any additional configuration to enable TLS — simply use couchbases:// in your connection string.

Capella’s root certificate is not signed by a well known CA (Certificate Authority). However, as the certificate is bundled with the SDK, it is trusted by default.

DNS SRV bootstrapping is enabled by default in the Ruby SDK. In order to make the SDK use the SRV records, you need to pass in the hostname from your records (here example.com):

options = Couchbase::ClusterOptions.new
options.authenticator = Couchbase::PasswordAuthenticator.new("Administrator", "password")
cluster = Cluster.connect("couchbases://couchbase.example.com?enable_dns_srv=true", options)

If the DNS SRV records could not be loaded properly you’ll get the message logged and the given host name will be used as an A record lookup.

[2020-09-07 14:30:26.358] [186383,186390] [warning] 47ms, DNS SRV query returned 0 records for "localhost", assuming that cluster is listening this address

Working in the Cloud

For most use cases, connecting client software using a Couchbase SDK to the Couchbase Capella service is similar to connecting to an on-premises Couchbase Cluster. The use of DNS-SRV, Alternate Address, and TLS is covered above.

We strongly recommend that the client and server are in the same LAN-like environment (e.g. AWS Region). As this may not always be possible during development, read the guidance on working with constrained network environments. More details on connecting your client code to Couchbase Capella can be found in the Cloud docs.

Troubleshooting Connections to Cloud

Some DNS caching providers (notably, home routers) can’t handle an SRV record that’s large — if you have DNS-SRV issues with such a set-up, reduce your DNS-SRV to only include three records. [For development only, not production.]. Our Troubleshooting Cloud Connections page will help you to diagnose this and other problems — as well as introducing the SDK doctor tool.

Further Reading

For more on RBAC, refer to the Server docs.