Embedded NATS

AnyCable supports running a NATS server as a part of the anycable-go WebSocket server. Thus, you don't need any external pub/sub services to build AnyCable clusters (i.e., having multiple WebSocket nodes).

🎥 Check out this AnyCasts episode to learn how to use AnyCable with embedded NATS on Fly.io

There are multiple ways to use this functionality:

• Single-server configuration
• Cluster configuration

Single-server configuration

The easiest way to start using embedded NATS in AnyCable is to run a single anycable-go instance with eNATS (this is how we call "Embedded NATS") enabled and connecting all other instances to it. This is how you can do that locally:

# first instance with NATS embedded
$ anycable-go --broadcast_adapter=nats --embed_nats --enats_addr=nats://0.0.0.0:4242

INFO 2023-02-28T00:06:45.618Z context=main Starting AnyCable 1.3.0
INFO 2023-02-28T00:06:45.649Z context=main Embedded NATS server started: nats://127.0.0.1:4242Copy to clipboardErrorCopied

Now you can run another WebSocket server connected to the first one:

anycable-go --port 8081 --broadcast_adapter=nats --nats_servers=nats://0.0.0.0:4242Copy to clipboardErrorCopied

RPC servers can also connect to the first AnyCable-Go server:

bundle exec anycable --broadcast_adapter=nats --nats_servers=nats://0.0.0.0:4242Copy to clipboardErrorCopied

This setup is similar to running a single NATS server independently.

Cluster configuration

Alternatively, you can form a cluster from embedded NATS instances. For that, you should start each anycable-go instance with a NATS cluster address and connect them together via the routes table:

# first instance
$ anycable-go --broadcast_adapter=nats --embed_nats --enats_addr=nats://0.0.0.0:4242 --enats_cluster=nats://0.0.0.0:4243

INFO 2023-02-28T00:06:45.618Z context=main Starting AnyCable 1.3.0
INFO 2023-02-28T00:06:45.649Z context=main Embedded NATS server started: nats://127.0.0.1:4242 (cluster: nats://0.0.0.0:4243, cluster_name: anycable-cluster)

# other instances
$ anycable-go --port 8081 --broadcast_adapter=nats --embed_nats --enats_addr=nats://0.0.0.0:4342 --enats_cluster=nats://0.0.0.0:4343 --enats_cluster_routes=nats://0.0.0.0:4243

INFO 2023-02-28T00:06:45.618Z context=main Starting AnyCable 1.3.0
INFO 2023-02-28T00:06:45.649Z context=main Embedded NATS server started: nats://127.0.0.1:4342 (cluster: nats://0.0.0.0:4343, cluster_name: anycable-cluster, routes: nats://0.0.0.0:4243)Copy to clipboardErrorCopied

See more information in the NATS documentation.

Using on Fly.io

AnyCable automatically infers sensible default configuration values for applications deployed to Fly.io.

To configure a cluster from embedded NATS servers, all you need is to turn the embedded NATS feature on and use the defaults. AnyCable automatically configures cluster addresses and routes to build a cluster within the current region.

See also Fly deployment documentation.

Super-cluster

You can also setup a super-cluster by configuring gateways:

# first cluster
$ anycable-go --broadcast_adapter=nats --embed_nats \
--enats_addr=nats://0.0.0.0:4242 --enats_cluster=nats://0.0.0.0:4243 \
--enats_gateway=nats://0.0.0.0:7222

# second cluster
$ anycable-go --port 8081 --broadcast_adapter=nats --embed_nats \
--enats_addr=nats://0.0.0.0:4342 --enats_cluster=nats://0.0.0.0:4343 \
--enats_gateway=nats://0.0.0.0:7322 \
--enats_gateways=anycable-cluster:nats://0.0.0.0:7222Copy to clipboardErrorCopied

NOTE: The value of the --enats_gateways parameter must be have a form <name>:<addr-1>,<addr-2>;<name-2>:<addr-3>,<addr-4>.

IMPORTANT: All servers in the cluster must have the same gateway configuration.

You can also specify the advertised address for the gateway (in case your cluster is behind a NAT) via the --enats_gateway_advertise parameter.

See more information in the NATS documentation.