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fix(alpine): build R with cairo, png, jpeg and tiff graphics devices

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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.
This commit is contained in:
Patrick Schratz 2026-09-18 09:02:37 +02:00
commit c144a0c8b9
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1 changed files with 130 additions and 11 deletions
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builder/Dockerfile.alpine-320
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@ -5,6 +5,13 @@ ENV OS_IDENTIFIER alpine-320
RUN set -x \
&& apk add -q R-dev curl ca-certificates bash g++ tzdata openjdk17 texmf-dist texlive-full tar sed patch tcl tk tk-dev xvfb libdeflate libdeflate-dev
# Graphics devices. R's configure only enables the cairo/png/jpeg/tiff devices
# when the corresponding headers are present at compile time, and pkgconf must
# exist for the pangocairo check to run at all. Without these, capabilities()
# reports cairo/png/jpeg/tiff as FALSE, and installing the runtime libraries
# afterwards cannot bring the compiled-out devices back.
RUN apk add -q pkgconf cairo-dev pango-dev fontconfig-dev freetype-dev libpng-dev jpeg-dev tiff-dev zlib-dev
# Install s5cmd for S3 uploads (much faster than AWS CLI)
RUN ARCH=$(uname -m); if [ "$ARCH" = "x86_64" ]; then S5CMD_ARCH="64bit"; else S5CMD_ARCH="arm64"; fi && \
curl -sL "https://github.com/peak/s5cmd/releases/download/v2.3.0/s5cmd_2.3.0_Linux-${S5CMD_ARCH}.tar.gz" | tar xz -C /usr/local/bin s5cmd
@ -18,7 +25,12 @@ RUN chmod 0777 /opt
# Override the default pager used by R
ENV PAGER /usr/bin/pager
ENV CONFIGURE_OPTIONS "--enable-R-shlib --with-tcltk --enable-memory-profiling --with-x=no --with-blas --with-lapack"
# X11 stays off: these are headless images, and the cairo/bitmap devices are
# detected independently of X11, so png()/svg() still work via cairo.
ENV CONFIGURE_OPTIONS "--enable-R-shlib --with-tcltk --enable-memory-profiling --with-x=no --with-cairo --with-libpng --with-jpeglib --with-libtiff --with-blas --with-lapack"
# Fail the build if a graphics device silently drops out again.
ENV REQUIRED_CAPABILITIES "cairo,png,jpeg,tiff"
COPY package.alpine-320 /package.sh
COPY build.sh .