The client port is the port VoltDB client applications use to communicate with the database cluster nodes. By default, VoltDB uses port 21212 as the client port. You can change the client port. However, all client applications must then use the specified port when creating connections to the cluster nodes.

To specify a different client port on the command line, use the --client flag when starting the VoltDB database. For example, the following command starts the database using port 12345 as the client port:

$ voltdb start -l ~/license.xml \
         -dir=~/mydb -H serverA \
         --client=12345

If you change the default client port, all client applications must also connect to the new port. The client interfaces for Java and C++ accept an additional, optional argument to the createConnection method for this purpose. The following examples demonstrate how to connect to an alternate port using the Java and C++ client interfaces.

Java

org.voltdb.client.Client voltclient;
voltclient = ClientFactory.createClient();
voltclient.createConnection("myserver",12345);  

C++

boost::shared_ptr<voltdb::Client> client = voltdb::Client::create();
client->createConnection("myserver", 12345);

The admin port is similar to the client port, it accepts and processes requests from applications. However, the admin port has the special feature that it continues to accept write requests when the database enters admin, or read-only, mode.

By default, VoltDB uses port 21211 on the default external network interface as the admin port. You can change the port assignment in the configuration file using the <admin-mode> tag or on the command line using the --admin flag. For example, the following configuration file sets the admin port to 2222:

<deployment>
   ...
   <admin-mode port="2222" />
</deployment>

The same effect can be achieved using the --admin flag on the command line:

$ voltdb start -l ~/license.xml \
         -dir=~/mydb -H serverA \
         --admin=2222

When the admin port is set in both the configuration file and on the command line, the command line setting supersedes the configuration file.

The web interface port is the port that VoltDB listens to for web-based connections. This port is used for both the JSON interface and access to the VoltDB Management Center. There are three related attributes associated with the web interface. The first attribute is whether the port is enabled. If the port is not enabled, then neither the JSON interface nor the Management Center are available from the cluster. The second attribute is which port to use. (Note that you can also use the --http flag on the command line to set the httpd port.) By default, the web interface is enabled and the default port is 8080. The third attribute is whether the web interface uses an unencrypted HTTP protocol or SSL encryption over HTTPS. By default, the web interface is not encrypted, but you can enable encryption using the <https> element in the configuration file.

<httpd port="8083">
        <jsonapi enabled="true"/>
</httpd>

http://athena.mycompany.com:8083/api/1.0/?Procedure=@SystemInformation

<httpd>
   <https enabled="true">
      <keystore path="/etc/mydb/keystore" password="twiddledee"/>
      <truststore path="/etc/mydb/truststore" password="twiddledum"/>
   </https>
</httpd>

$ java -cp $HOME/voltdb/lib/jetty-util*.jar \
  org.eclipse.jetty.util.security.Password twiddledee

A VoltDB cluster uses ports to communicate among the cluster nodes. This port is internal to VoltDB and should not be used by other applications.

By default, the internal server port is port 3021 for all nodes in the cluster^[2]. You can specify an alternate port using the --internal flag when starting the VoltDB process. For example, the following command starts the VoltDB process using an internal port of 4000:

$ voltdb start -l ~/license.xml \
         -dir=~/mydb -H serverA \
          --internal=4000

During database replication, the replica uses a dedicated port to connect to the master database. By default, the replication port is port 5555. You can use a different port by specifying a different port number either on the voltdb command line or in the configuration file.

Adding the replication port to the configuration file is useful when setting the port for all nodes in the cluster. Using the command line option is useful for changing the default port for only one node in the cluster or for specifying a specific network interface. If you specify the replication port in both the configuration file and on the command line, the command line argument takes precedence.

VoltDB uses a version of Apache Zookeeper to communicate among supplementary functions that require coordination but are not directly tied to database transactions. Zookeeper provides reliable synchronization for functions such as command logging without interfering with the database's own internal communications.

VoltDB uses a network port bound to the local interface (127.0.0.1) to interact with Zookeeper. By default, 7181 is assigned as the Zookeeper port for VoltDB. You can specify a different port number using the --zookeeper flag when starting the VoltDB process. It is also possible to specify a different network interface, like with other ports. However, accepting the default for the zookeeper network interface is recommended where possible. For example:

$ voltdb start -l ~/license.xml \
         -dir=~/mydb -H serverA \
         --zookeeper=2288