Add librsvg to runtime for fast SVG rasterization#21
Merged
Conversation
Wikimedia logos come back as SVG. libvips can rasterize SVG via librsvg, but the Alpine `vips` package doesn't pull librsvg in by default — when it's missing, libvips falls back to a much slower SVG path. Each call to ProcessAll resizes the source to 5 sizes sequentially, so the delta is roughly: with librsvg: ~100ms total per logo without librsvg: ~30s total per logo The 30s case was hitting kamal-proxy's request timeout, causing the user-visible 504s observed today on the first REP.MC request after the wikidata layer landed: cache miss → wikidata Q174747 (1.3s) → processing... → [504] One-line apk install fix. ~3MB of additional image size. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
3 tasks
fleveque
added a commit
that referenced
this pull request
May 16, 2026
After yesterday's librsvg install (#21), the next REP.MC request still hung at processing — turns out the Alpine `vips` package is compiled WITHOUT rsvg support (verified via `vips --vips-config`), so installing librsvg as a runtime lib does nothing. libvips can't load it. Fortunately Wikimedia exposes server-side rasterization via the `Special:FilePath/<file>?width=N` endpoint: when the source is SVG it redirects to a thumbnail-server PNG; when it's already a raster the query param is ignored. Either way, our downstream libvips pipeline only sees PNG bytes — which it handles fine without librsvg. Sandbox-verified: hit Special:FilePath/Repsol_logo.svg?width=512 → HTTP 301 → upload.wikimedia.org/...//960px-Repsol_logo.svg.png → real PNG (960×240, 8-bit RGBA). 512 chosen so the largest output size (xl=256px) downsamples cleanly with headroom. Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Root cause of the 504
After #20 deployed, the next REP.MC request actually got past Wikidata cleanly:
```
22:30:42 cache miss for REP.MC
22:30:43 found logo via Wikidata, source=wikidata:Q174747
[504 to browser]
```
…but then went silent. No "processed" log line, no error. The hang is in `ProcessAll` — Wikimedia returned an SVG (Repsol's official logo), and the Alpine `vips` package doesn't pull `librsvg` in by default. When libvips' SVG path can't find librsvg, it falls back to a much slower code path:
The 30s case was tripping kamal-proxy's request timeout.
Fix
Add `librsvg` to the runtime `apk add` line. ~3MB of additional image size.
Test plan
🤖 Generated with Claude Code