Pulsar proxy

Pulsar proxy is an optional gateway. Pulsar proxy is used when direct connections between clients and Pulsar brokers are either infeasible or undesirable. For example, when you run Pulsar in a cloud environment or on Kubernetes or an analogous platform, you can run Pulsar proxy.

Configure the proxy

Before using the proxy, you need to configure it with the brokers addresses in the cluster. You can configure the broker URL in the proxy configuration, or the proxy to connect directly using service discovery.

In a production environment service discovery is not recommended.

Use broker URLs

It is more secure to specify a URL to connect to the brokers.

Proxy authorization requires access to ZooKeeper, so if you use these broker URLs to connect to the brokers, you need to disable authorization at the Proxy level. Brokers still authorize requests after the proxy forwards them.

You can configure the broker URLs in conf/proxy.conf as follows.

brokerServiceURL=pulsar://brokers.example.com:6650
brokerWebServiceURL=http://brokers.example.com:8080
functionWorkerWebServiceURL=http://function-workers.example.com:8080

If you use TLS, configure the broker URLs in the following way:

brokerServiceURLTLS=pulsar+ssl://brokers.example.com:6651
brokerWebServiceURLTLS=https://brokers.example.com:8443
functionWorkerWebServiceURL=https://function-workers.example.com:8443

The hostname in the URLs provided should be a DNS entry which points to multiple brokers or a virtual IP address, which is backed by multiple broker IP addresses, so that the proxy does not lose connectivity to Pulsar cluster if a single broker becomes unavailable.

The ports to connect to the brokers (6650 and 8080, or in the case of TLS, 6651 and 8443) should be open in the network ACLs.

Note that if you do not use functions, you do not need to configure functionWorkerWebServiceURL.

Use service discovery

Pulsar uses ZooKeeper for service discovery. To connect the proxy to ZooKeeper, specify the following in conf/proxy.conf.

metadataStoreUrl=my-zk-0:2181,my-zk-1:2181,my-zk-2:2181
configurationMetadataStoreUrl=my-zk-0:2184,my-zk-remote:2184

To use service discovery, you need to open the network ACLs, so the proxy can connects to the ZooKeeper nodes through the ZooKeeper client port (port 2181) and the configuration store client port (port 2184).

However, it is not secure to use service discovery. Because if the network ACL is open, when someone compromises a proxy, they have full access to ZooKeeper.

Start the proxy

To start the proxy:

$ cd /path/to/pulsar/directory
$ bin/pulsar proxy \
  --metadata-store zk:my-zk-1:2181,my-zk-2:2181,my-zk-3:2181 \
  --configuration-metadata-store zk:my-zk-1:2181,my-zk-2:2181,my-zk-3:2181

You can run multiple instances of the Pulsar proxy in a cluster.

Stop the proxy

Pulsar proxy runs in the foreground by default. To stop the proxy, simply stop the process in which the proxy is running.

Proxy frontends

You can run Pulsar proxy behind some kind of load-distributing frontend, such as an HAProxy load balancer.

Use Pulsar clients with the proxy

Once your Pulsar proxy is up and running, preferably behind a load-distributing frontend, clients can connect to the proxy via whichever address that the frontend uses. If the address is the DNS address pulsar.cluster.default, for example, the connection URL for clients is pulsar://pulsar.cluster.default:6650.

For more information on Proxy configuration, refer to Pulsar proxy.