reinstate doc upload

.github/workflows/docs.yml

@@ -14,6 +14,7 @@ jobs:
     uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
     with:
       repository: pytorch/vision
+      upload-artifact: docs
       script: |
         set -euo pipefail
 
@@ -44,4 +45,58 @@ jobs:
         sed -i -e 's/-j auto/-j 1/' Makefile
         make html
 
-        mv build/html/* "${RUNNER_DOCS_DIR}"
+        cp -r build/html "${RUNNER_ARTIFACT_DIR}"
+
+        # On PRs we also want to upload the docs into our S3 bucket for preview.
+        if [[ ${{ github.event_name == 'pull_request' }} ]]; then
+          cp -r build/html/* "${RUNNER_DOCS_DIR}"
+        fi
+
+  upload:
+    # FIXME: this also needs to happen on created releases
+#    # FIXME: enable this before the PR is merged
+#    if: github.event_name == 'push' && github.event.push.base_ref == 'main'
+    needs: build
+    uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
+    with:
+      repository: pytorch/vision
+      download-artifact: docs
+      ref: gh-pages
+      script: |
+        set -euo pipefail
+
+        TARGET="main"
+
+        mkdir -p "${TARGET}"
+        rm -rf "${TARGET}"/*
+        mv "${RUNNER_ARTIFACT_DIR}"/html/* "${TARGET}"
+        git add "${TARGET}" || true
+
+        if [[ "${TARGET}" == main ]]; then
+          mkdir -p _static
+          rm -rf _static/*
+          cp -r "${TARGET}"/_static/* _static
+          git add _static || true
+        fi
+
+        git config user.email "soumith+bot@pytorch.org"
+        git config user.name "pytorchbot"
+        git commit -m "auto-generating sphinx docs" || true
+
+        # FIXME: this needs to come from ${{ secrets }}
+        export GITHUB_PYTORCHBOT_TOKEN=FOO
+        {
+          echo "machine github.com"
+          echo "login pytorchbot"
+          echo "password ${GITHUB_PYTORCHBOT_TOKEN}"
+        } > ~/.netrc
+
+        # FIXME: remove this before the PR is merged. GHA automatically redacts secrets in the
+        #  logs, so we are not leaking anything here. This just makes sure this workflow is
+        # able to push correctly after we merge the PR.
+        git status
+        cat ~/.netrc
+
+        git remote add origin https://github.com/pytorch/vision.git
+#        FIXME: enable this before the PR is merged
+#        git push -u origin gh-pages