Managing Connections

  • how-to
    This section describes how to connect the PHP 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 is to call new Cluster() with a connection string and a ClusterOptions object containing your credentials:

    $connectionString = "couchbase://localhost";
    $opts = new \Couchbase\ClusterOptions();
    $opts->credentials("Administrator", "password");
    $cluster = new \Couchbase\Cluster($connectionString, $opts);
    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:

    $opts = new ClusterOptions();
    $opts->credentials("Administrator", "password");
    $connectionString = "couchbase://,";
    $cluster = new Cluster($connectionString, $opts);
    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
    Connection string with two seed nodes,
    Connection string with two parameters

    A connection string may optionally be prefixed by either "couchbase://" or, for TLS, "couchbases://".

    Connection Options

    The backend implementation of connection strings parameters changed substantially in 4.0. See more details on migrating to 4.0.

    Configuring client settings with ClusterOptions() is the preferred option. More details can be found in the API reference.

    Connection Lifecycle

    Most of the high-level classes in the PHP 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 NAT’d 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.

    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 instead of a connection string.

    $opts = new ClusterOptions();
    $opts->credentials("Administrator", "password");
    $connectionString = "couchbase://,";
    $cluster = new Cluster($connectionString, $opts);
    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 io.networkResolution 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). That 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 verification the SDK uses the following certificates:

    • The certificates in the Mozilla Root CA bundle (bundled with the SDK as of 4.1.4 and obtained from curl).

    • The certificates in OpenSSL’s default certificate store (as of 4.1.0).

    • The self-signed root certificate that is used to sign Capella Certificates (bundled with the SDK as of 4.0.0).

    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 using the disable_mozilla_ca_certificates connection string parameter.

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

    $  php -r 'print_r(Couchbase\Extension\version());'
        [mozilla_ca_bundle_date] => Tue Jan 10 04:12:06 2023 GMT
        [mozilla_ca_bundle_embedded] => 1
        [mozilla_ca_bundle_sha256] => fb1ecd641d0a02c01bc9036d513cb658bbda62a75e246bedbc01764560a639f0
        [mozilla_ca_bundle_size] => 137
        [openssl_default_cert_dir] => /opt/homebrew/etc/openssl@3/certs
        [openssl_default_cert_dir_env] => SSL_CERT_DIR
        [openssl_default_cert_file] => /opt/homebrew/etc/openssl@3/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:

    [2023-05-17 15:54:23.907] [28822,310461] [debug] 7ms, [6d92f0-c4ba-d843-9d86-3c6839a2bed362]: loading 137 CA certificates from Mozilla bundle. Update date: "Tue Jan 10 04:12:06 2023 GMT", SHA256: "fb1ecd641d0a02c01bc9036d513cb658bbda62a75e246bedbc01764560a639f0"
    • Couchbase Capella

    • Couchbase Server

    The PHP 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.

    Certificates from the Mozilla Root CA store are now bundled with the SDK. If the server’s certificate is signed by a well-known CA (e.g., GoDaddy, Verisign, etc.), you don’t need to configure the trust_certiciate path in your connection string.

    You can still provide a certificate explicitly if necessary:

    1. Get the CA certificate from the cluster and save it in a text file.

    2. Enable encryption on the client side and point it to the file containing the certificate.

    It is important to make sure you are transferring the certificate in an encrypted manner from the server to the client side, so either copy it through SSH or through a similar secure mechanism.

    If you are running on localhost and just want to enable TLS for a development machine, just copying and pasting it suffices — so long as you use rather than localhost in the connection string. This is because the certificate will not match the name localhost.

    Navigate in the admin UI to Settings  Cluster and copy the input box of the TLS certificate into a file on your machine (which we will refer to as cluster.crt). It looks similar to this:

    -----END CERTIFICATE-----

    The next step is to enable encryption by connecting to a cluster with the 'couchbases://' protocol in the connection string and pass it the path to the certificate file via '?trust_certificate=…​' in the connection string itself.

    $opts = new ClusterOptions();
    $opts->credentials("Administrator", "password");
    $connectionString = "couchbases://localhost?trust_certificate=/path/to/ca/certificates.pem";
    $cluster = new Cluster($connectionString, $opts);

    Then use this custom Cluster when opening the connection to the cluster.

    If you want to verify it’s actually working, you can use a tool like tcpdump. For example, an unencrypted upsert request looks like this (using sudo tcpdump -i lo0 -A -s 0 port 11210):


    After enabling encryption, you cannot inspect the traffic in cleartext (same upsert request, but watched on port 11207 which is the default encrypted port):

    ..... ...xuG.O=.#.........?.Q)8..D...S.W.4.-#....@7...^.Gk.4.t..C+......6..)}......N..m..o.3...d.,.	...W.....U..

    Using DNS SRV records

    As an alternative to specifying multiple hosts in your program, you can get the actual bootstrap node list from a DNS SRV record. The following steps are necessary to make it work:

    1. Set up your DNS server to respond properly from a DNS SRV request.

    2. Enable it on the SDK and point it towards the DNS SRV entry.

    Your DNS server should be set up like this (one row for each bootstrap node):  3600  IN  SRV  0  0  11210  3600  IN  SRV  0  0  11210  3600  IN  SRV  0  0  11210
    The ordering, priorities, and weighting are completely ignored and should not be set on the records to avoid ambiguities.

    If you plan to use secure connections, you use _couchbases instead:  3600  IN  SRV  0  0  11207  3600  IN  SRV  0  0  11207  3600  IN  SRV  0  0  11207

    DNS SRV bootstrapping is available in the PHP SDK from version 3.0. In order to make the SDK actually use the SRV records, you need to enable DNS SRV on the environment and pass in the host name from your records (here

    $opts = new ClusterOptions();
    $opts->credentials("Administrator", "password");
    $connectionString = "couchbase://";
    $cluster = new Cluster($connectionString, $opts);

    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

    Also, if you pass in more than one node, DNS SRV bootstrap will not be initiated:

    Working in the Cloud

    For most use cases, connecting client software using a Couchbase SDK to the new 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.