The [gossip] configuration

The [gossip] block configures the peer-to-peer API. Corrosion uses QUIC (UDP) to exchange information between nodes of a cluster.

Required fields

gossip.addr

Socket address reachable from other nodes in the cluster. Listens on UDP for QUIC packets.

Optional fields

gossip.bootstrap

List of node addresses from the cluster for the initial join. Defaults to an empty array.

It's recommended to use a partial list of nodes that overlap. The cluster discover nodes it doesn't know about automatically via SWIM.

Simple example:

bootstrap = ["127.0.0.1:3333", "127.0.0.1:3334"]

It can resolve names (using the system's DNS resolver):

bootstrap = ["my-fly-app.internal:3333"]

It can resolve names w/ a custom DNS server:

bootstrap = ["my-fly-app.internal:3333@[fdaa::3]:53"]

gossip.plaintext

Allows using QUIC without encryption. The only reason to set this to true is if you're running a toy cluster or if the underlying transport is already handling cryptography (such as WireGuard) AND authorization is bound by the network (such is the case for a Fly.io app's private network).

gossip.idle_timeout_secs

The max idle timeout in seconds for QUIC connection.

Defaults to 30 seconds.

gossip.max_mtu

Define the max MTU for QUIC. Instead of attempting to discover the best MTU value automatically, you can define this upper bound.

This should be your "effective" MTU: network interface's MTU - IP header size - UDP header size. For example, if the MTU on your network interface is 1500 and you're listening on IPv6, you'll need to subtract 40 bytes for the IP header and 8 bytes for the UDP header (you'd set max_mtu = 1452).

gossip.disable_gso

Certain environments don't support GSO (Generic Segmentation Offload). This is detected by the QUIC implementation, but it's possible to pre-emptively disable it to avoid re-trying the initial packets without GSO as it is detected as unavailable.

gossip.tls

Strong encryption is highly recommended for any non-development usage of Corrosion.

You can easily generate the necessary certificates using corrosion tls.

Using gossip.tls.insecure = true means the certificate's signing authority won't be checked.

[gossip.tls] # optional
cert_file = "/path/to/server_cert.pem"
key_file = "/path/to/server_key.pem"
ca_file = "/path/to/ca_cert.pem" # optional
insecure = false # optional

It's also possible to specify client certification authorization (mutual TLS or mTLS):

[gossip.tls.client] # optional
cert_file = "/path/to/client_cert.pem"
key_file = "/path/to/client_key.pem"

Example config (w/ default values)

[gossip]
addr = "" # required, no default value

bootstrap = []

plaintext = false  # optional
max_mtu = 1200  # optional
disable_gso = false  # optional

[gossip.tls] # optional
cert_file = "/path/to/server_cert.pem"
key_file = "/path/to/server_key.pem"
ca_file = "/path/to/ca_cert.pem" # optional
insecure = false # optional

[gossip.tls.client] # optional
cert_file = "/path/to/client_cert.pem"
key_file = "/path/to/client_key.pem"