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explain clustering - #929
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| the cluster. | ||
| each sized for its workload. This is how OpenFn's own cloud runs. As on Docker | ||
| Engine, every web app pod is active, and on GKE the pods join one Erlang cluster | ||
| on their own. For the database, use a high-availability managed Postgres service |
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@taylordowns2000 Does on their own. equate to using Gossip? if so, I am not sure that is correct - we provision a service in GKE and pass that service (via K8S_HEADLESS_SERVICE) to Cluster.Strategy.Kubernetes.DNS (provided by libcluster).
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Good call. Have removed. Thank you!
| Outside Kubernetes, Lightning finds other nodes with gossip by default. Gossip | ||
| uses UDP multicast, which most cloud networks block between VMs. On Docker | ||
| Engine across several hosts, set `ERLANG_NODE_DISCOVERY_VIA_POSTGRES_ENABLED` to | ||
| `true` so nodes find each other through the Postgres database they already | ||
| share. |
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Docker Engine side only, that's what I've deployed Lightning clustered on.
One thing the tip could add. Postgres discovery only finds peers; the connection is still plain TCP, so you also need the same RELEASE_COOKIE, RELEASE_DISTRIBUTION=name, RELEASE_NODE as a reachable address rather than a container id, a pinned port (ERL_AFLAGS=-kernel inet_dist_listen_min 9100 inet_dist_listen_max 9100) and the firewall open for epmd 4369 plus that port.
Set only the flag and the nodes discover each other and still can't connect.
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Ah ok, let's make sure this information lives in Zeus
Tedion
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Tedion
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Docker Engine side reads right to me. I'll get the connection-level details into Zeus: the shared RELEASE_COOKIE, RELEASE_NODE as a reachable address, the pinned distribution port, and the firewall rule for epmd 4369 plus that port.
@bensonmiller , @rorymckinley , @Tedion , heard there was some confusion about how clustering works in Erlang and thought this might be useful! does this line up with your understanding?
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