36 lines
1.8 KiB
Markdown
36 lines
1.8 KiB
Markdown
---
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layout: "docs"
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page_title: "Gossip Protocol"
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sidebar_current: "docs-internals-gossip"
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description: |-
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Nomad uses a gossip protocol to manage membership. All of this is provided
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through the use of the Serf library.
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---
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# Gossip Protocol
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Nomad uses a [gossip protocol](https://en.wikipedia.org/wiki/Gossip_protocol)
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to manage membership. This is provided through the use of the [Serf library](https://www.serf.io/).
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The gossip protocol used by Serf is based on
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["SWIM: Scalable Weakly-consistent Infection-style Process Group Membership Protocol"](https://www.cs.cornell.edu/~asdas/research/dsn02-swim.pdf),
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with a few minor adaptations. There are more details about [Serf's protocol here](https://www.serf.io/docs/internals/gossip.html).
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~> **Advanced Topic!** This page covers technical details of
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the internals of Nomad. You do not need to know these details to effectively
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operate and use Nomad. These details are documented here for those who wish
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to learn about them without having to go spelunking through the source code.
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## Gossip in Nomad
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Nomad makes use of a single global WAN gossip pool that all servers participate in.
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Membership information provided by the gossip pool allows servers to perform cross region
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requests. The integrated failure detection allows Nomad to gracefully handle an entire region
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losing connectivity, or just a single server in a remote region. The gossip protocol
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is also used to detect servers in the same region to perform automatic clustering
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via the [consensus protocol](/docs/internals/consensus.html).
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All of these features are provided by leveraging [Serf](https://www.serf.io/). It
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is used as an embedded library to provide these features. From a user perspective,
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this is not important, since the abstraction should be masked by Nomad. It can be useful
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however as a developer to understand how this library is leveraged.
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