Add base-path so the web UI can be served under a path prefix#17
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florianl
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May 5, 2026
florianl
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Thanks for the contribution!
Just a minor issue: Can we use strings.ReplaceAll() instead of the boiler platte, that is introduced by html/template?
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Thank you @florianl! |
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Summary
--base-pathflag andBASE_PATHenv var to allow serving the web UI and API under a sub-path prefix (e.g./firepit)fetch()calls use the correct prefixed URLs/to<base-path>/when a base path is configuredMotivation
On the OTel Demo Firepit will be deployed behind Envoy.
Without this change the browser fetches
/api/*instead of/<whatever>/api/*, breaking the UI entirely.Changes
cmd/firepit/main.goBasePath stringtoConfigand wired up the flag/env varnormalizeBasePathenforces a leading slash and strips any trailing slashstartWebUIServerrefactored intobuildWebUIMux(testable without starting a real listener) andstartWebUIServer/,/api/*,/debug/pprof/*) are now prefixed withcfg.BasePathindex.htmlis served as a parsed Go template that injects{{.BasePath}}into awindow.__BASE_PATH__script tag; all other static assets are served by the existing stripped file serverBasePath != "", a redirect handler sends/→<base-path>/cmd/firepit/web/index.html<script>window.__BASE_PATH__ = '{{.BasePath}}';</script>in<head>fetch()calls now prefix withwindow.__BASE_PATH__cmd/firepit/main_test.goTestNormalizeBasePath— unit tests for the normalization helperTestLoadConfigBasePath— env var parsing, including edge cases (/, trailing slash, no leading slash)TestWebUIServerBasePath— integration-style tests usingbuildWebUIMuxdirectly, covering redirect behaviour and prefixed routes for both the empty and/firepitcases