156 lines
5.5 KiB
HTML
156 lines
5.5 KiB
HTML
<!doctype html>
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<html>
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<meta charset="utf-8" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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href="https://cdnjs.cloudflare.com/ajax/libs/github-markdown-css/5.5.1/github-markdown.min.css"
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<title>haunt98 posts</title>
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</head>
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<style>
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.markdown-body {
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box-sizing: border-box;
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min-width: 200px;
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margin: 0 auto;
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padding: 45px;
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font-family:
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Shantell Sans Normal,
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Rec Mono Casual,
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</style>
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<body class="markdown-body">
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<h2>
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<a href="index.html"><code>~</code></a>
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</h2>
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<div class="markdown-heading">
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<h1 class="heading-element">Reload config</h1>
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<a
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id="user-content-reload-config"
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class="anchor"
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aria-label="Permalink: Reload config"
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href="#reload-config"
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><span aria-hidden="true" class="octicon octicon-link"></span
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></a>
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</div>
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<p>This serves as design draft of reload config system</p>
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<div class="highlight highlight-source-wsd">
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<pre><span class="pl-k">@startuml</span> Reload config
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<span class="pl-k">skinparam</span> <span class="pl-k">defaultFontName</span> <span class="pl-s">Iosevka Term SS08</span>
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<span class="pl-k">participant</span> <span class="pl-c1">admin</span>
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<span class="pl-k">participant</span> <span class="pl-c1">other_service</span>
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<span class="pl-k">participant</span> <span class="pl-c1">config_service</span>
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<span class="pl-k">participant</span> <span class="pl-c1">storage</span>
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<span class="pl-k">==</span> <span class="pl-s">Admin handle</span> <span class="pl-k">==</span>
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<span class="pl-c1">admin</span> <span class="pl-k">-></span> <span class="pl-c1">config_service</span>: set/update/delete config
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<span class="pl-c1">config_service</span> <span class="pl-k">-></span> <span class="pl-c1">storage</span>: set/update/delete config
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<span class="pl-k">==</span> <span class="pl-s">Other service handle</span> <span class="pl-k">==</span>
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">other_service</span>: init service
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<span class="pl-k">activate</span> <span class="pl-c1">other_service</span>
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">storage</span>: make connection
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<span class="pl-k">loop</span>
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">storage</span>: listen on config change
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">other_service</span>: save config to memory
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<span class="pl-k">end</span>
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<span class="pl-k">deactivate</span> <span class="pl-c1">other_service</span>
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">other_service</span>: do business
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<span class="pl-k">activate</span> <span class="pl-c1">other_service</span>
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">other_service</span>: get config
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<span class="pl-c1">other_service</span> <span class="pl-k">-></span> <span class="pl-c1">other_service</span>: do other business
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<span class="pl-k">deactivate</span> <span class="pl-c1">other_service</span>
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<span class="pl-k">@enduml</span></pre>
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</div>
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<p>
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Config storage can be any key value storage or database like etcd, Consul,
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mySQL, ...
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</p>
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<p>
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If storage is key value storage, maybe there is API to listen on config
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change. Otherwise we should create a loop to get all config from storage
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for some interval, for example each 5 minute.
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</p>
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<p>
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Each <code>other_service</code> need to get config from its memory, not
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hit <code>storage</code>. So there is some delay between upstream config
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(config in <code>storage</code>) and downstream config (config in
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<code>other_service</code>), but maybe we can forgive that delay (???).
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</p>
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<p>Pros:</p>
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<ul>
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<li>
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<p>
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Config can be dynamic, service does not need to restart to apply new
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config.
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</p>
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</li>
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<li>
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<p>
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Each service only keep 1 connection to <code>storage</code> to listen
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to config change, not hit <code>storage</code> for each request.
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</p>
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</li>
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</ul>
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<p>Cons:</p>
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<ul>
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<li>Each service has 1 more dependency, aka <code>storage</code>.</li>
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<li>
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Need to handle fallback config, incase <code>storage</code> failure.
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</li>
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<li>Delay between upstream/downstream config</li>
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</ul>
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<div>
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Feel free to ask me via
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<a href="mailto:hauvipapro+posts@gmail.com">email</a> or
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<a rel="me" href="https://hachyderm.io/@haunguyen">Mastodon</a>.
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<br />Source code is available on
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<a href="https://github.com/haunt98/posts-go">GitHub</a>
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<a href="https://codeberg.org/yoshie/posts-go">Codeberg</a>
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<a href="https://git.sr.ht/~youngyoshie/posts-go">sourcehut</a>
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<a href="https://gitea.treehouse.systems/yoshie/posts-go">Treehouse</a>
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<a href="https://gitlab.com/youngyoshie/posts-go">GitLab</a>
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</div>
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</body>
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</html>
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