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r-builds/CLAUDE.md
pat-s c144a0c8b9
 fix(alpine): build R with cairo, png, jpeg and tiff graphics devices 
The Alpine builder images install R-dev but never the graphics headers.
R's configure treats those as optional and does not fail when they are
absent, so the build succeeds and ships an R whose capabilities() reports
cairo, png, jpeg and tiff as FALSE. Installing the runtime libraries on
the target system afterwards cannot bring compiled-out devices back.

Note that --with-x=no was not the cause. R's bitmap and pangocairo checks
run independently of R_X11, and libpng was in fact found. capabilities("png")
needs a device backend, and with X11 off and cairo absent there was none,
which is why all four read FALSE. X11 stays off: these are headless images
and cairo covers png()/jpeg()/tiff()/svg().

- Install pkgconf, cairo-dev, pango-dev, fontconfig-dev, freetype-dev,
  libpng-dev, jpeg-dev, tiff-dev and zlib-dev in every Alpine builder image.
- Pass --with-cairo, --with-libpng, --with-jpeglib and --with-libtiff
  explicitly so the intent is visible next to --with-x=no.
- Assert REQUIRED_CAPABILITIES after make install, so a build that loses a
  device fails instead of being packaged and uploaded. Opt-in per Dockerfile,
  leaving the other platforms untouched.
- Add a FORCE_REBUILD escape hatch to the dedup step. Artifact filenames
  carry only the R version, so the HEAD probe would otherwise keep skipping
  every Alpine version and serving the stale broken binaries.
- Record the three gotchas in CLAUDE.md.

Verified by compiling R 4.5.1 in the patched alpine-322 image: jpeg, png,
tiff and cairo are TRUE, default bitmapType is cairo, and all four devices
render. The guard was exercised in both directions against that build.
2026-09-18 09:02:37 +02:00

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CLAUDE.md

CI pipelines (Crow, in .crow/) that build R binaries and upload them to Backblaze B2.

Conventions

  • PRs: the remote is Forgejo on git.devxy.io; use fj -H git.devxy.io (not gh).
  • Storage: Backblaze B2 bucket devxy-r-builds (endpoint configured in .crow/build.yaml).

Gotchas

  • B2 requires authentication for the list-bucket API. Anonymous GET only works for individual public-read objects — an empty bucket listing usually means missing credentials, not an empty bucket. This silently broke rebuild dedup once.
  • R's configure silently disables graphics devices when headers are missing. It never fails the build, so a missing -dev package yields a working R whose capabilities() reports cairo, png, jpeg and tiff as FALSE. Installing the runtime libraries on the target system afterwards cannot bring compiled-out devices back; the binary has to be rebuilt. builder/build.sh therefore asserts REQUIRED_CAPABILITIES (set per Dockerfile) after make install.
  • The --with-x=no on the Alpine images does not disable cairo. R's bitmap and pangocairo checks run independently of R_X11, so png() and svg() work headless via cairo.
  • Artifact filenames carry only the R version, not the builder image. When a builder change alters the resulting binary, dedup would keep serving the stale artifact forever; set FORCE_REBUILD in .crow/build.yaml to rebuild and overwrite in place.
  • When a pipeline fails, fetch the Crow logs yourself instead of asking the user to paste them, and monitor reruns in the background until green.