mirror of https://github.com/hashicorp/consul
54 lines
2.9 KiB
Go
54 lines
2.9 KiB
Go
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// Package proxycfg provides a component that monitors local agent state for
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// Connect proxy service registrations and maintains the necessary cache state
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// for those proxies locally. Local cache state keeps pull based proxies (e.g.
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// the built in one) performant even on first request/startup, and allows for
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// push-based proxy APIs (e.g. xDS for Envoy) to be notified of updates to the
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// proxy configuration.
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//
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// The relationship with other agent components looks like this:
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//
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// +------------------------------------------+
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// | AGENT |
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// | |
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// | +--------+ 1. +----------+ |
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// | | local |<-----+ proxycfg |<--------+ |
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// | | state +----->| Manager |<---+ | |
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// | +--------+ 2. +^---+-----+ | | |
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// | 5.| | | | |
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// | +----------+ | +-------+--+ |4. |
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// | | +->| proxycfg | | |
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// | | 3.| | State | | |
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// | | | +----------+ | |
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// | | | | |
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// | | | +----------+ | |
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// | | +->| proxycfg +-+ |
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// | | | State | |
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// | | +----------+ |
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// | |6. |
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// | +----v---+ |
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// | | xDS | |
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// | | Server | |
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// | +--------+ |
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// | |
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// +------------------------------------------+
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//
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// 1. Manager watches local state for changes.
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// 2. On local state change manager is notified and iterates through state
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// looking for proxy service registrations.
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// 3. For each proxy service registered, the manager maintains a State
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// instance, recreating on change, removing when deregistered.
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// 4. State instance copies the parts of the the proxy service registration
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// needed to configure proxy, and sets up blocking watches on the local
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// agent cache for all remote state needed: root and leaf certs, intentions,
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// and service discovery results for the specified upstreams. This ensures
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// these results are always in local cache for "pull" based proxies like the
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// built-in one.
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// 5. If needed, pull-based proxy config APIs like the xDS server can Watch the
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// config for a given proxy service.
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// 6. Watchers get notified every time something changes the current snapshot
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// of config for the proxy. That might be changes to the registration,
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// certificate rotations, changes to the upstreams required (needing
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// different listener config), or changes to the service discovery results
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// for any upstream (e.g. new instance of upstream service came up).
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package proxycfg
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