[lens0021]

Requested by lens0021 · project thread

Part of femiwiki/femiwiki#671. Adds chart-renderer/, a Node.js function that Extension:Chart calls through $wgChartServiceUrl. With it, the wiki host needs neither Node.js nor a higher $wgMaxShellMemory. Node 22 does not start under the default 300 MB ulimit -v, and it does not start under 600 MB either.

How

• It bundles Wikimedia's chart-renderer at commit 543b8ee with esbuild. Only renderChart() and validateRequestParams() are used, not the express/service-runner server, so the zip holds one 4.8 MB index.js (139 MB of node_modules otherwise).

• No stored secret. Chart can't add headers, so the URL path is a JWT that STS signs for the instance role Femiwiki with GetWebIdentityToken. This is the same mechanism google-subject-token.php already uses. The function checks the following before reading the body:

  • the ES384 signature, against the account issuer's JWKS
  • iss, aud = chart-renderer, sub = the role ARN, and exp

  Tokens live an hour and are refreshed every 15 minutes, so a URL leaked into a log stops working soon.

• deploy.yml gains runtime/handler per target. The uv steps skip Node targets, and a Node target runs npm ci --ignore-scripts && npm test before zipping. test.yml gets a chart-renderer job, and dependabot watches its npm lockfile.

Measured locally

The five upstream examples render in 11–98 ms each, with about 80 MB RSS after loading and 113 MB peak, so 256 MB of memory should be enough. Cold load of the bundle takes 160 ms.

Order

The function itself (Node 22 on arm64, function URL, reserved concurrency) comes from a femiwiki/infra PR, which must be applied before this merges. Otherwise the deploy fails on a function that doesn't exist yet. The wiki side (token cron and $wgChartServiceUrl) follows in docker-mediawiki.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.05%. Comparing base (6d121d7) to head (44a7174).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #230   +/-   ##
=======================================
  Coverage   96.05%   96.05%           
=======================================
  Files          10       10           
  Lines        1116     1116           
=======================================
  Hits         1072     1072           
  Misses         44       44           

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[lens0021]

Closing: the renderer now lives in femiwiki/terraform-aws-mediawiki-chart-renderer, which ships the bundled code itself, and femiwiki/infra#1567 deploys it from there.

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