Struct nats::Options [−][src]
pub struct Options { /* fields omitted */ }
Expand description
Connect options.
Implementations
Options
for establishing a new NATS Connection
.
Example
let options = nats::Options::new();
let nc = options.connect("demo.nats.io")?;
Authenticate with NATS using a token.
Example
let nc = nats::Options::with_token("t0k3n!")
.connect("demo.nats.io")?;
Authenticate with NATS using a username and password.
Example
let nc = nats::Options::with_user_pass("derek", "s3cr3t!")
.connect("demo.nats.io")?;
Authenticate with NATS using a .creds
file.
This will open the provided file, load its creds, perform the desired authentication, and then zero the memory used to store the creds before continuing.
Example
let nc = nats::Options::with_credentials("path/to/my.creds")
.connect("connect.ngs.global")?;
Authenticate with NATS using a static credential str, using
the creds file format. Note that this is more hazardous than
using the above with_credentials
method because it retains
the secret in-memory for the lifetime of this client instead
of zeroing the credentials after holding them for a very short
time, as the with_credentials
method does.
Example
let creds =
"-----BEGIN NATS USER JWT-----
eyJ0eXAiOiJqd3QiLCJhbGciOiJlZDI1NTE5...
------END NATS USER JWT------
************************* IMPORTANT *************************
NKEY Seed printed below can be used sign and prove identity.
NKEYs are sensitive and should be treated as secrets.
-----BEGIN USER NKEY SEED-----
SUAIO3FHUX5PNV2LQIIP7TZ3N4L7TX3W53MQGEIVYFIGA635OZCKEYHFLM
------END USER NKEY SEED------
";
let nc = nats::Options::with_static_credentials(creds)
.expect("failed to parse static creds")
.connect("connect.ngs.global")?;
Authenticate with a function that loads user JWT and a signature function.
Example
let seed = "SUANQDPB2RUOE4ETUA26CNX7FUKE5ZZKFCQIIW63OX225F2CO7UEXTM7ZY";
let kp = nkeys::KeyPair::from_seed(seed).unwrap();
fn load_jwt() -> std::io::Result<String> {
todo!()
}
let nc = nats::Options::with_jwt(load_jwt, move |nonce| kp.sign(nonce).unwrap())
.connect("localhost")?;
Authenticate with NATS using a public key and a signature function.
Example
let nkey = "UAMMBNV2EYR65NYZZ7IAK5SIR5ODNTTERJOBOF4KJLMWI45YOXOSWULM";
let seed = "SUANQDPB2RUOE4ETUA26CNX7FUKE5ZZKFCQIIW63OX225F2CO7UEXTM7ZY";
let kp = nkeys::KeyPair::from_seed(seed).unwrap();
let nc = nats::Options::with_nkey(nkey, move |nonce| kp.sign(nonce).unwrap())
.connect("localhost")?;
Set client certificate and private key files.
Example
let nc = nats::Options::new()
.client_cert("client-cert.pem", "client-key.pem")
.connect("nats://localhost:4443")?;
Set the default TLS config that will be used
for connections. Note that this is less secure
than specifying TLS certificate file paths
using the other methods on Options
, which
will avoid keeping raw key material in-memory
and will zero memory buffers that temporarily
contain key material during connection attempts.
This is intended to be used as a method of
last-resort when providing well-known file
paths is not feasible.
To avoid version conflicts, the rustls
version
used by this crate is exported as nats::rustls
.
Example
let mut tls_client_config = nats::rustls::ClientConfig::default();
tls_client_config
.set_single_client_cert(
vec![nats::rustls::Certificate(b"MY_CERT".to_vec())],
nats::rustls::PrivateKey(b"MY_KEY".to_vec()),
);
let nc = nats::Options::new()
.tls_client_config(tls_client_config)
.connect("nats://localhost:4443")?;
Add a name option to this configuration.
Example
let nc = nats::Options::new()
.with_name("My App")
.connect("demo.nats.io")?;
Select option to not deliver messages that we have published.
Example
let nc = nats::Options::new()
.no_echo()
.connect("demo.nats.io")?;
Set the maximum number of reconnect attempts. If no servers remain that are under this threshold, then no further reconnect shall be attempted. The reconnect attempt for a server is reset upon successfull connection. If None then there is no maximum number of attempts.
Example
let nc = nats::Options::new()
.max_reconnects(3)
.connect("demo.nats.io")?;
Set the maximum amount of bytes to buffer when accepting outgoing traffic in disconnected mode.
The default value is 8mb.
Example
let nc = nats::Options::new()
.reconnect_buffer_size(64 * 1024)
.connect("demo.nats.io")?;
Establish a Connection
with a NATS server.
Multiple servers may be specified by separating them with commas.
Example
let options = nats::Options::new();
let nc = options.connect("demo.nats.io")?;
In the below case, the second server is configured
to use TLS but the first one is not. Using the
tls_required
method can ensure that all
servers are connected to with TLS, if that is
your intention.
let options = nats::Options::new();
let nc = options.connect("nats://demo.nats.io:4222,tls://demo.nats.io:4443")?;
Set a callback to be executed when connectivity to a server has been lost.
Example
let nc = nats::Options::new()
.disconnect_callback(|| println!("connection has been lost"))
.connect("demo.nats.io")?;
Set a callback to be executed when connectivity to a server has been reestablished.
Example
let nc = nats::Options::new()
.reconnect_callback(|| println!("connection has been reestablished"))
.connect("demo.nats.io")?;
Set a custom JetStream
API prefix. This is useful
when using JetStream
through exports/imports.
Example
let nc = nats::Options::new()
.jetstream_api_prefix("some_exported_prefix".to_string())
.connect("demo.nats.io")?;
nc.drain().unwrap();
Set a callback to be executed when the client has been closed due to exhausting reconnect retries to known servers or by completing a drain request.
Example
let nc = nats::Options::new()
.close_callback(|| println!("connection has been closed"))
.connect("demo.nats.io")?;
nc.drain().unwrap();
Set a callback to be executed for calculating the backoff duration to wait before a server reconnection attempt.
The function takes the number of reconnects as an argument
and returns the Duration
that should be waited before
making the next connection attempt.
It is recommended that some random jitter is added to
your returned Duration
.
Example
let nc = nats::Options::new()
.reconnect_delay_callback(|c| Duration::from_millis(std::cmp::min((c * 100) as u64, 8000)))
.connect("demo.nats.io")?;
Setting this requires that TLS be set for all server connections.
If you only want to use TLS for some server connections, you may
declare them separately in the connect string by prefixing them
with tls://host:port
instead of nats://host:port
.
Examples
let nc = nats::Options::new()
.tls_required(true)
.connect("tls://demo.nats.io:4443")?;