Configuration

leafnodes Configuration Block

The leaf node configuration block is used to configure incoming as well as outgoing leaf node connections. Most properties are for the configuration of incoming connections. The properties remotes and reconnect are for outgoing connections.

Property Description
host Interface where the server will listen for incoming leafnode connections.
port Port where the server will listen for incoming leafnode connections (default is 7422).
listen Combines host and port as <host>:<port>
tls TLS configuration block (same as other nats-server tls configuration).
advertise Hostport <host>:<port> to advertise how this server can be contacted by leaf nodes. This is useful in cluster setups with NAT.
no_advertise if true the server shouldn’t be advertised to leaf nodes.
authorization Authorization block. See Authorization Block section below.
remotes List of remote entries specifying servers where leafnode client connection can be made.
reconnect Interval in seconds at which reconnect attempts to a remote server are made.

Authorization Block

Property Description
user Username for the leaf node connection.
password Password for the user entry.
account Account this leaf node connection should be bound to.
timeout Maximum number of seconds to wait for leaf node authentication.
users List of credentials and account to bind to leaf node connections. See User Block section below.

Users Block

Property Description
user Username for the leaf node connection.
password Password for the user entry.
account Account this leaf node connection should be bound to.

Here are some examples of using basic user/password authentication for leaf nodes (note while this is using accounts it is not using JWTs)

Singleton mode:

  1. leafnodes {
  2.   port: ...
  3.   authorization {
  4.     user: leaf
  5.     password: secret
  6.     account: TheAccount
  7.   }
  8. }

With above configuration, if a soliciting server creates a Leafnode connection with url: nats://leaf:secret@host:port, then the accepting server will bind the leafnode connection to the account “TheAccount”. This account need to exist otherwise the connection will be rejected.

Multi-users mode:

  1. leafnodes {
  2.   port: ...
  3.   authorization {
  4.     users = [
  5.       {user: leaf1, password: secret, account: account1}
  6.       {user: leaf2, password: secret, account: account2}
  7.     ]
  8.   }
  9. }

With the above, if a server connects using leaf1:secret@host:port, then the accepting server will bind the connection to account account1. If using leaf2 user, then the accepting server will bind to connection to account2.

If username/password (either singleton or multi-users) is defined, then the connecting server MUST provide the proper credentials otherwise the connection will be rejected.

If no username/password is provided, it is still possible to provide the account the connection should be associated with:

  1. leafnodes {
  2.   port: ...
  3.   authorization {
  4.     account: TheAccount
  5.   }
  6. }

With the above, a connection without credentials will be bound to the account “TheAccount”.

If other form of credentials are used (jwt, nkey or other), then the server will attempt to authenticate and if successful associate to the account for that specific user. If the user authentication fails (wrong password, no such user, etc..) the connection will be also rejected.

LeafNode remotes Entry Block

Property Description
url Leafnode URL (URL protocol should be nats-leaf).
urls Leafnode URL array. Supports multiple URLs for discovery, e.g., urls: [ “nats-leaf://host1:7422”, “nats-leaf://host2:7422” ]
account Account name or JWT public key identifying the local account to bind to this remote server. Any traffic locally on this account will be forwarded to the remote server.
credentials Credential file for connecting to the leafnode server.
tls A TLS configuration block. Leafnode client will use specified TLS certificates when connecting/authenticating.
ws_compression If connecting with Websocket protocol, this boolean (true or false) indicates to the remote server that it wishes to use compression. The default is false.
ws_no_masking If connecting with Websocket protocol, this boolean indicates to the remote server that it wishes not to mask outbound WebSocket frames. The default is false, which means that outbound frames will be masked.

Connecting using WebSocket protocol

Since NATS 2.2.0, Leaf nodes support outbound WebSocket connections by specifying ws as the scheme component of the remote server URLs:

  1. leafnodes {
  2.   remotes [
  3.     {urls: ["ws://hostname1:443", "ws://hostname2:443"]}
  4.   ]
  5. }

Note that if a URL has the ws scheme, all URLs the list must be ws. You cannot mix and match. Therefore this would be considered an invalid configuration:

  1.   remotes [
  2.     # Invalid configuration that will prevent the server from starting
  3.     {urls: ["ws://hostname1:443", "nats-leaf://hostname2:7422"]}
  4.   ]

Note that the decision to make a TLS connection is not based on wss:// (as opposed to ws://) but instead in the presence of a TLS configuration in the leafnodes{} or the specific remote configuration block.

To configure Websocket in the remote server, check the Websocket section.

tls Configuration Block

Property Description
cert_file TLS certificate file.
key_file TLS certificate key file.
ca_file TLS certificate authority file.
insecure Skip certificate verification.
verify If true, require and verify client certificates.
verify_and_map If true, require and verify client certificates and use values map certificate values for authentication purposes.
cipher_suites When set, only the specified TLS cipher suites will be allowed. Values must match golang version used to build the server.
curve_preferences List of TLS cypher curves to use in order.
timeout TLS handshake timeout in fractional seconds.