57 lines
3.1 KiB
Go
57 lines
3.1 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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// Package proxycfg contains components for sourcing the data required to
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// configure Connect proxies. The Manager provides an API with which proxy
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// services can be registered, and coordinates the fetching (and refreshing)
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// of intentions, upstreams, discovery chain, certificates etc. Consumers
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// such as the xDS server can then subscribe to receive snapshots of this
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// data whenever it changes.
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//
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// Consul client agents support the configuration of proxies locally
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// registered to them, whereas Consul servers support both this and proxies
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// in the catalog.
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//
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// The following diagram depicts the component relationships on a server, as
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// this is the more complex mode of operation:
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//
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// +-------+ 1. +------------+
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// | Local | ◀------------▶ | Local |
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// | State | | State Sync |
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// +-------+ +-----+------+
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// ▲ |
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// +-------+ | +---------------+ | 2.
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// | envoy | 4. | 4a. | Local | |
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// +-------+ | +-▶ | Config Source +-+ |
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// | stream | | +---------------+ | |
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// ▼ | | ▼ ▼
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// +--------+ 3. +-+-+-----------+ 6. +----------+ 2a. +----------+
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// | xDS +---▶ | Catalog +-----▶ | proxycfg +----▶ | proxycfg |
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// | Server | ◀---+ Config Source +-----▶ | Manager +--+ | State |
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// +--------+ 8. +----+----------+ 7. +----------+ | +----------+
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// 5. | |
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// ▼ 7a. | +----------+
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// +-------+ +-▶ | proxycfg |
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// | State | | State |
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// | Store | +----------+
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// +-------+
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//
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// 1. local.Sync watches the agent's local state for changes.
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// 2. If any sidecar proxy or gateway services are registered to the local agent
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// they are sync'd to the proxycfg.Manager.
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// 2a. proxycfg.Manager creates a state object for the service and begins
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// pre-fetching data (go to 8).
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// 3. Client (i.e., envoy) begins a stream and the xDS server calls Watch on its
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// ConfigSource - on a client agent this would be a local config source, on a
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// server it would be a catalog config source.
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// 4. On server, the catalog config source will check if service is registered locally.
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// 4a. If the service *is* registered locally it hands off the the local config
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// source, which calls Watch on the proxycfg manager (and serves the pre-
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// fetched data).
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// 5. Otherwise, it fetches the service from the state store.
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// 6. It calls Watch on the proxycfg manager.
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// 7. It registers the service with the proxycfg manager.
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// 7a. See: 2a.
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// 8. xDS server receives snapshots of configuration data whenever it changes.
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package proxycfg
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