Add build script for PRs

Author: nkammah

.buildkite/scripts/build_pr.sh

@@ -1,2 +1,91 @@
 #!/bin/bash
-echo "nothing to see yet"
+set -euo pipefail
+set +x
+
+# This script should only be invoked by the Buildkite PR bot
+if [ -z ${GITHUB_PR_BRANCH+set} ] || [ -z ${GITHUB_PR_TARGET_BRANCH+set} ] || [ -z ${GITHUB_PR_NUMBER+set} ] || [ -z ${GITHUB_PR_BASE_REPO+set} ];then
+  echo "One of the following env. variable GITHUB_PR_BRANCH, GITHUB_PR_TARGET_BRANCH, GITHUB_PR_NUMBER, GITHUB_PR_BASE_REPO is missing - exiting."
+  exit 1
+fi
+
+# Set some metadata for build filtering capabilities
+# https://buildkite.com/elastic/docs-build-pr/builds?meta_data[repo_pr]=tech-content_123
+buildkite-agent meta-data set "repo_pr" "${GITHUB_PR_BASE_REPO}_${GITHUB_PR_NUMBER}"
+
+rebuild_opt=""
+build_args=""
+TARGET_BRANCH=""
+
+# Define build docs arguments
+if [[ ${GITHUB_PR_COMMENT_VAR_REBUILD_OPT:="unset"} == "rebuild" ]];then
+  rebuild_opt=" --rebuild"
+elif [[ ${GITHUB_PR_COMMENT_VAR_SKIP_OPT:="unset"} == "skiplinkcheck" ]];then
+  build_args+=" --skiplinkcheck"
+  if [[ ${GITHUB_PR_COMMENT_VAR_WARN_OPT:="unset"} == "warnlinkcheck" ]];then
+    build_args+=" --warnlinkcheck"
+  fi
+fi
+
+buildkite-agent \
+    annotate \
+    --style "info" \
+    --context 'docs-info' \
+    "Triggered by a doc change in elastic/$GITHUB_PR_BASE_REPO PR: [#$GITHUB_PR_NUMBER](https://github.com/elastic/$GITHUB_PR_BASE_REPO/pull/$GITHUB_PR_NUMBER)"
+
+
+if [[ "${GITHUB_PR_BASE_REPO}" != 'docs' ]]; then
+  # Buildkite PR bot for repositories other than the `elastic/docs` repo are configured to
+  # always checkout the master branch of the `elastic/docs` repo (where the build logic resides).
+  # We first need to checkout the product repo / branch in a sub directory, that we'll reference
+  # in the build process.
+  echo "Cloning the ${GITHUB_PR_BASE_REPO} PR locally"
+
+  git clone --reference /opt/git-mirrors/elastic-$GITHUB_PR_BASE_REPO \
+    [email protected]:elastic/$GITHUB_PR_BASE_REPO.git ./product-repo
+
+  cd ./product-repo &&
+      git fetch origin pull/$GITHUB_PR_NUMBER/head:$GITHUB_PR_BRANCH &&
+      git switch $GITHUB_PR_BRANCH &&
+      cd ..
+
+  build_args+=" --sub_dir $GITHUB_PR_BASE_REPO:$GITHUB_PR_TARGET_BRANCH:./product-repo"
+else
+  # Buildkite PR bot for the `elastic/docs` repo is configured to checkout the PR directly into the workspace
+  # We don't have to do anything else in this case.
+
+  # Per https://github.com/elastic/docs/issues/1821, always rebuild all
+   # books for PRs to the docs repo, for now.
+   # When https://github.com/elastic/docs/issues/1823 is fixed, this
+   # should be removed and the original behavior restored.
+   rebuild_opt=" --rebuild"
+fi
+
+
+# Set the target branch and preview options
+TARGET_BRANCH="${GITHUB_PR_BASE_REPO}_bk_${GITHUB_PR_NUMBER}"
+PREVIEW_URL="https://${TARGET_BRANCH}.docs-preview.app.elstc.co"
+
+build_cmd="./build_docs --all --keep_hash \
+    --target_repo [email protected]:elastic/built-docs \
+    --reference /opt/git-mirrors/ \
+    --target_branch ${TARGET_BRANCH} \
+    --push \
+    --announce_preview ${PREVIEW_URL}/diff \
+    ${rebuild_opt} \
+    ${build_args}"
+
+echo "The following build command will be used"
+echo $build_cmd
+
+# Kick off the build
+ssh-agent bash -c "ssh-add && $build_cmd"
+
+buildkite-agent annotate \
+    --style "success" \
+    --context 'docs-info' \
+     --append \
+    "<br>Preview url: ${PREVIEW_URL}"
+
+buildkite-agent meta-data set pr_comment:doc-preview:head " * Documentation preview
+   - 📚 [HTML diff](${PREVIEW_URL}/diff)
+   - 📙 [Preview](${PREVIEW_URL})"