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docs: remove references to serf.io site (#24114)
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The serf.io site is being taken down, so change all our links to point to the
repo docs instead.

Ref: hashicorp/serf#743
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tgross authored Oct 2, 2024
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7 changes: 4 additions & 3 deletions nomad/server.go
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Expand Up @@ -1644,9 +1644,10 @@ func (s *Server) setupSerf(conf *serf.Config, ch chan serf.Event, path string) (
return nil, err
}
}
// LeavePropagateDelay is used to make sure broadcasted leave intents propagate
// This value was tuned using https://www.serf.io/docs/internals/simulator.html to
// allow for convergence in 99.9% of nodes in a 10 node cluster
// LeavePropagateDelay is used to make sure broadcasted leave intents
// propagate This value was tuned using
// https://github.com/hashicorp/serf/blob/master/docs/internals/simulator.html.erb
// to allow for convergence in 99.9% of nodes in a 10 node cluster
conf.LeavePropagateDelay = 1 * time.Second
conf.Merge = &serfMergeDelegate{}

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38 changes: 22 additions & 16 deletions website/content/docs/concepts/gossip.mdx
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Expand Up @@ -8,11 +8,11 @@ description: |-

# Gossip Protocol

Nomad uses a [gossip protocol](https://en.wikipedia.org/wiki/Gossip_protocol)
to manage membership. This is provided through the use of the [Serf library](https://www.serf.io/).
The gossip protocol used by Serf is based on
["SWIM: Scalable Weakly-consistent Infection-style Process Group Membership Protocol"](https://www.cs.cornell.edu/projects/Quicksilver/public_pdfs/SWIM.pdf),
with a few minor adaptations. There are more details about [Serf's protocol here](https://www.serf.io/docs/concepts/gossip.html).
Nomad uses the [Serf library][serf] to provide a [gossip
protocol](https://en.wikipedia.org/wiki/Gossip_protocol) to manage membership.
The gossip protocol used by Serf is based on ["SWIM: Scalable Weakly-consistent
Infection-style Process Group Membership Protocol"][swim], with a few minor
adaptations. There are more details about [Serf's protocol here][gossip].

~> **Advanced Topic!** This page covers technical details of
the internals of Nomad. You do not need to know these details to effectively
Expand All @@ -21,14 +21,20 @@ to learn about them without having to go spelunking through the source code.

## Gossip in Nomad

Nomad makes use of a single global WAN gossip pool that all servers participate in.
Membership information provided by the gossip pool allows servers to perform cross region
requests. The integrated failure detection allows Nomad to gracefully handle an entire region
losing connectivity, or just a single server in a remote region. The gossip protocol
is also used to detect servers in the same region to perform automatic clustering
via the [consensus protocol](/nomad/docs/concepts/consensus).

All of these features are provided by leveraging [Serf](https://www.serf.io/). It
is used as an embedded library to provide these features. From a user perspective,
this is not important, since the abstraction should be masked by Nomad. It can be useful
however as a developer to understand how this library is leveraged.
Nomad makes use of a single global WAN gossip pool that all servers participate
in. Membership information provided by the gossip pool allows servers to perform
cross region requests. The integrated failure detection allows Nomad to
gracefully handle an entire region losing connectivity, or just a single server
in a remote region. Nomad also uses the gossip protocol to detect servers in the
same region to perform automatic clustering via the [consensus
protocol](/nomad/docs/concepts/consensus).

To provide all these features, Nomad uses [Serf][serf] as an embedded
library. From a user perspective, this is not important, since Nomad masks the
abstraction. However, developers may find it useful to understand how Nomad
leverages the Serf library.


[serf]: https://github.com/hashicorp/serf
[gossip]: https://github.com/hashicorp/serf/blob/master/docs/internals/gossip.html.markdown
[swim]: https://www.cs.cornell.edu/projects/Quicksilver/public_pdfs/SWIM.pdf
9 changes: 5 additions & 4 deletions website/content/docs/concepts/security.mdx
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Expand Up @@ -333,14 +333,15 @@ There are two main components to consider to for external threats in a Nomad clu

### Network Ports

| **Port / Protocol** | Agents | Description |
| -------------------- | ------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Port / Protocol** | Agents | Description |
|----------------------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **4646** / TCP | All | [HTTP](https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol) to provide [UI](/nomad/tutorials/web-ui/web-ui-access) and [API](/nomad/api-docs) access to agents. |
| **4647** / TCP | All | [RPC](https://en.wikipedia.org/wiki/Remote_procedure_call) protocol used by agents. |
| **4648** / TCP + UDP | Servers | [gossip](/nomad/docs/concepts/gossip) protocol to manage server membership using [Serf](https://www.serf.io/). |
| **4647** / TCP | All | [RPC](https://en.wikipedia.org/wiki/Remote_procedure_call) protocol used by agents. |
| **4648** / TCP + UDP | Servers | [gossip](/nomad/docs/concepts/gossip) protocol to manage server membership using [Serf][serf]. |


[api_metrics]: /nomad/api-docs/metrics
[api_status_peers]: /nomad/api-docs/status#list-peers
[Variables]: /nomad/docs/concepts/variables
[verify_https_client]: /nomad/docs/configuration/tls#verify_https_client
[serf]: https://github.com/hashicorp/serf

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