47 lines
3.9 KiB
HTML
47 lines
3.9 KiB
HTML
<!doctype html><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><link rel=stylesheet href=https://cdnjs.cloudflare.com/ajax/libs/github-markdown-css/5.1.0/github-markdown-dark.css><style>.markdown-body{box-sizing:border-box;min-width:200px;max-width:980px;margin:0 auto;padding:45px}@media(max-width:767px){.markdown-body{padding:15px}}</style><body class=markdown-body><a href=index>Index</a><h1><a id=user-content-reload-config class=anchor aria-hidden=true href=#reload-config><span aria-hidden=true class="octicon octicon-link"></span></a>Reload config</h1><p>This serves as design draft of reload config system<div class="highlight highlight-source-wsd"><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></div><p>Config storage can be any key value storage or database like etcd, Consul, mySQL, ...<p>If storage is key value storage, maybe there is API to listen on config change.
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Otherwise we should create a loop to get all config from storage for some interval, for example each 5 minute.<p>Each <code>other_service</code> need to get config from its memory, not hit <code>storage</code>.
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So there is some delay between upstream config (config in <code>storage</code>) and downstream config (config in <code>other_service</code>), but maybe we can forgive that delay (???).<p>Pros:<ul><li><p>Config can be dynamic, service does not need to restart to apply new config.<li><p>Each service only keep 1 connection to <code>storage</code> to listen to config change, not hit <code>storage</code> for each request.</ul><p>Cons:<ul><li>Each service has 1 more dependency, aka <code>storage</code>.<li>Need to handle fallback config, incase <code>storage</code> failure.<li>Delay between upstream/downstream config</ul><a href=mailto:hauvipapro+posts@gmail.com>Feel free to ask me via email</a>
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