Create a CRAN-like binary distribution repository.

Use a gh-pages branch for GitHub pages hosting of
a CRAN-like repository. When a release is created,
there is a workflow that automatically updates the
CRAN-like repository using the information from the
release assets. Note that the CRAN-like repository
does not include the binary packages themselves,
it forwards to the URLs of the release assets on
GitHub.

Author: zivy

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
       fail-fast: false
       matrix:
         R: [ '4.4.3', '4.5.3', '4.6.0' ]
-        os: [ 'macos-15-intel', 'ubuntu-latest', 'windows-latest']
+        os: [ 'macos-15-intel', 'ubuntu-24.04', 'windows-latest']
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.R }} ${{ matrix.os }} build
 
@@ -66,44 +66,56 @@ jobs:
       env:
         ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS: 2
       run: |
-        R -e "Sys.setenv(MAKEJ=2); remotes::install_git(c('.'), lib=Sys.getenv('R_LIBS_USER'))"
+        R -e "Sys.setenv(MAKEJ=2); remotes::install_git(c('.'), lib=Sys.getenv('R_LIBS_USER'), upgrade='never', INSTALL_opts='--build')"
         R -e "library(SimpleITK); Version()"
-    - name: Create binary package from installed package
-      id: create_package
+    - name: Rename package artifact
+    # The original artifact name is SimpleITK_<sitk_version>.zip (windows),
+    # SimpleITK_<sitk_version>.tgz (macOS), or SimpleITK_<sitk_version>.tar.gz (Linux).
+    # This is irrespective of the R version. We need to rename them so that they are
+    # unique. Otherwise we could not upload artifacts for different
+    # R versions because the names collide.
+      id: rename_package
       shell: bash
       run: |
-        # Get the R version for naming
-        R_VERSION_SHORT=$(echo "${{ matrix.R }}" | cut -d'.' -f1,2)
+        # canonical approach to collecting build artifacts in a directory for upload
+        mkdir -p artifacts
 
-        # Get package version from DESCRIPTION
-        PKG_VERSION=$(Rscript -e "cat(read.dcf(file.path(Sys.getenv('R_LIBS_USER'), 'SimpleITK', 'DESCRIPTION'), 'Version')[1])")
+        # remotes::install_git(..., INSTALL_opts='--build') writes a valid package
+        # file into the current working directory (GITHUB_WORKSPACE).
+        PKG_PATH=$(find "${GITHUB_WORKSPACE}" -maxdepth 1 -type f \
+          \( -name 'SimpleITK_*.tgz' -o -name 'SimpleITK_*.zip' -o -name 'SimpleITK_*.tar.gz' \) \
+          | head -n 1)
 
-        # Create output directory for artifacts
-        mkdir -p artifacts
+        if [[ -z "${PKG_PATH}" ]]; then
+          echo "No built package artifact found in ${GITHUB_WORKSPACE}."
+          exit 1
+        fi
+
+        # package naming is SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_${OS_ARCHIVE_EXT}
+        R_VERSION_SHORT=$(echo "${{ matrix.R }}" | cut -d'.' -f1,2)
+        PKG_VERSION=$(Rscript -e "cat(read.dcf('DESCRIPTION', 'Version')[1])")
 
-        # Create binary package archive from installed package (no recompilation)
-        cd "${R_LIBS_USER}"
         if [[ "$RUNNER_OS" == "macOS" ]]; then
           PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_macos-x86_64.tgz"
-          tar czf "${GITHUB_WORKSPACE}/artifacts/${PKG_NAME}" SimpleITK
         elif [[ "$RUNNER_OS" == "Linux" ]]; then
           PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_linux-x86_64.tar.gz"
-          tar czf "${GITHUB_WORKSPACE}/artifacts/${PKG_NAME}" SimpleITK
         elif [[ "$RUNNER_OS" == "Windows" ]]; then
           PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_windows-x86_64.zip"
-          7z a -tzip "${GITHUB_WORKSPACE}/artifacts/${PKG_NAME}" SimpleITK
+        else
+          echo "Unsupported OS: $RUNNER_OS"
+          exit 1
         fi
 
-        cd "${GITHUB_WORKSPACE}"
+        mv "${PKG_PATH}" "${GITHUB_WORKSPACE}/artifacts/${PKG_NAME}"
         ls -lh artifacts/
 
         # Export PKG_NAME as output for use in upload step
         echo "pkg_name=${PKG_NAME}" >> $GITHUB_OUTPUT
     - name: Upload binary package
-      if: steps.create_package.outcome == 'success'
+      if: steps.rename_package.outcome == 'success'
       uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
       with:
-        name: ${{ steps.create_package.outputs.pkg_name }}
+        name: ${{ steps.rename_package.outputs.pkg_name }}
         path: artifacts/*
         retention-days: 30
 
@@ -161,8 +173,43 @@ jobs:
         draft: true
         name: SimpleITK ${{ github.ref_name }} R Package Release
         body: |
-          Please review and test the packages before publishing this release.
-          Then remove the "Draft" status to make it public and delete this message.
+          **Please review and test the packages before publishing this release. Then remove this line and make it public.**
+
+          Detailed release notes are available on the [main SimpleITK repository](https://github.com/SimpleITK/SimpleITK/releases/${{ github.ref_name }}).
+
+          The GitHub Pages repository provides platform-specific binaries. If a binary is not available, you will need to build SimpleITK locally using the remotes installer. See the [README](https://github.com/${{ github.repository }}/blob/main/README.md) for detailed instructions.
+
+          Windows and macOS:
+
+          ```r
+          install.packages(
+            "SimpleITK",
+            repos = c("https://simpleitk.github.io/SimpleITKRInstaller/${{ github.ref_name }}"),
+            type = "binary"
+          )
+          ```
+
+          Linux:
+
+          ```r
+          install.packages(
+            "SimpleITK",
+            repos = NULL,
+            contriburl = paste0(
+              "https://simpleitk.github.io/SimpleITKRInstaller/${{ github.ref_name }}/__linux__/ubuntu-noble/",
+              paste(R.version$major, sub("\\..*$", "", R.version$minor), sep = "."),
+              "/src/contrib"
+            ),
+            type = "source"
+          )
+          ```
+
+          The Linux install above uses a "source" type installation even though it is binary, due to the way R handles binary packages on this platform.
+
+          If for some reason you decided to download the package artifact from this release page, before you install the package you will need to first unzip the file. Then rename it to SimpleITK_<version>.zip (windows), SimpleITK_<version>.tgz (macOS), or SimpleITK_<version>.tar.gz (Linux) to match the expected file name format.
+
+          ```r
+
         files: |
           release-artifacts/*
         fail_on_unmatched_files: true

.github/workflows/update_gh_cran.yml

@@ -0,0 +1,59 @@
+name: Update CRAN Repository
+
+on:
+  release:
+    types: [published]
+
+permissions:
+  contents: write
+
+concurrency:
+  group: update-cran-repository
+  cancel-in-progress: false
+
+jobs:
+  update-repo:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+          ref: main
+
+      - name: Set up R
+        uses: r-lib/actions/setup-r@a51a8012b0aab7c32ef9d19bf54da93f3254335e # v2.12.0
+
+      - name: Download Release Assets
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          mkdir -p temp_packages
+          gh release download ${{ github.event.release.tag_name }} --dir temp_packages
+
+      - name: Route Assets and Build PACKAGES Files
+        shell: bash
+        run: |
+          # Run the R script and always do the cleanup of the temp_packages directory,
+          # step returns the exit code from the R script.
+          (
+            Rscript update_cran_repo.R \
+              --packages_dir temp_packages \
+              --base_cran_dir . \
+              --repo_url https://github.com/${{ github.repository }} \
+              --tag ${{ github.event.release.tag_name }}
+            status=$?
+            rm -rf temp_packages
+            exit $status
+          )
+
+      - name: Commit and Push Changes
+        run: |
+          git config --global user.name "github-actions[bot]"
+          git config --global user.email "github-actions[bot]@users.noreply.github.com"
+          git checkout gh-pages
+          git add .
+          if ! git diff --cached --quiet; then
+            git commit -m "Update CRAN repository index for release ${{ github.event.release.tag_name }}"
+            git push
+          fi