Add the capability to copy release artifacts

1. Add the capability to copy release artifacts to a specified location.
2. Add the capability to skip the github release process.

In order to make artifacts available from CI runs, we need to copy them
to a location known to our workflow.  Since we don't want to rely on
bazel's internal directory hierarchy, we'll make the release process
copy the release artifacts to a user-specified subdirectory.

Signed-off-by: Chris Frantz <cfrantz@google.com>

release/release.template.bash

@@ -6,12 +6,15 @@ function usage() {
     echo "bazel run @@LABEL@@ -- [options] [release_tag]"
     echo "    -R|--repo <[HOST/]OWNER/REPO> : Select another repository"
     echo "    -d|--draft                    : Save the release as a draft instead of publishing it"
-    echo "    --dry-run                     : Print the GitHub CLI invocation"
+    echo "    --[no]dry-run                 : Print the GitHub CLI invocation"
     echo "    -p|--prerelease               : Mark the release as a prerelease"
     echo "    -t|--title <string>           : Release title"
     echo "    -n|--notes <string>           : Release notes"
     echo "    -F|--notes-file <file>        : Read release notes from file"
     echo "    --target <branch>             : Target branch or git commit SHA"
+    echo "    --[no]script                  : Run (or skip) the 'script' portion of process"
+    echo "    --[no]release                 : Perform (or skip) the relese process on github"
+    echo "    --copy <subdir>               : Copy the release artifacts to the named subdir"
     echo "    -h|-?|--help                  : This message"
     echo
     echo "If a release_tag is not given, the last git tag is assumed to be the"
@@ -26,6 +29,14 @@ function run() {
     fi
 }
 
+function option_or_no() {
+  if [[ "$1" == "--no"* ]]; then
+    echo 0
+  else
+    echo 1
+  fi
+}
+
 ARTIFACTS=(@@ARTIFACTS@@)
 FILES=(@@FILES@@)
 GH=@@GH@@
@@ -43,8 +54,12 @@ TITLE=()
 NOTES=()
 GENERATE_NOTES=("--generate-notes")
 DRY_RUN=0
+SCRIPT=1
+RELEASE=1
+COPY=""
 
 # Parse the same set of arguments as `gh release create`.
+shopt -s extglob
 while [[ $# -gt 0 ]];
 do
     case "$1" in
@@ -56,8 +71,9 @@ do
             DRAFT=("--draft")
             shift
             ;;
-        --dry-run|--dry_run)
+        --?(no)dry[-_]run)
             DRY_RUN=1
+            DRY_RUN=$(option_or_no "$1")
             shift
             ;;
         -p|--prerelease)
@@ -82,6 +98,18 @@ do
             BRANCH="$2"
             shift 2
             ;;
+        --copy)
+            COPY="$2"
+            shift 2
+            ;;
+        --?(no)release)
+            RELEASE=$(option_or_no "$1")
+            shift
+            ;;
+        --?(no)script)
+            SCRIPT=$(option_or_no "$1")
+            shift
+            ;;
         -\?|-h|--help)
             usage
             exit
@@ -102,7 +130,7 @@ if [[ -z "${RELEASE_TAG}" ]]; then
     RELEASE_TAG=$(cd "$BUILD_WORKSPACE_DIRECTORY" && git describe --abbrev=0 --tags)
 fi
 
-if $(${GH} release list | egrep -q "\s${RELEASE_TAG}\s"); then
+if [[ ${RELEASE} == 1 ]] && $(${GH} release list | egrep -q "\s${RELEASE_TAG}\s"); then
     echo "A release with tag ${RELEASE_TAG} already exists."
     echo
     echo "To make a new release, create a new tag first or specify the tag on"
@@ -119,15 +147,28 @@ done
 
 export ARTIFACTS BRANCH FILES GH REMOTE RELEASE_TAG DIGEST
 
-# A script fragment substituted in from the `release` rule.
-@@SCRIPT@@
-# End script.
+if [[ ${SCRIPT} == 1 ]]; then
+    # Do something in case the substitution is empty.
+    true
+    # A script fragment substituted in from the `release` rule.
+    @@SCRIPT@@
+    # End script.
+fi
+
+if [[ ! -z "${COPY}" ]]; then
+    run mkdir -p "${COPY}"
+    # We use `--no-preserve=mode` because bazel creates files
+    # with mode 0444.
+    run cp --no-preserve=mode -t "${COPY}" "${FILES[@]}"
+fi
 
-run ${GH} release "${REPO[@]}" create \
-    --target="${BRANCH}" "${RELEASE_TAG}" \
-    "${DRAFT[@]}" \
-    "${PRERELEASE[@]}" \
-    "${TITLE[@]}" \
-    "${GENERATE_NOTES[@]}" \
-    "${NOTES[@]}" \
-    "${ARTIFACTS[@]}"
+if [[ ${RELEASE} == 1 ]]; then
+    run ${GH} release "${REPO[@]}" create \
+        --target="${BRANCH}" "${RELEASE_TAG}" \
+        "${DRAFT[@]}" \
+        "${PRERELEASE[@]}" \
+        "${TITLE[@]}" \
+        "${GENERATE_NOTES[@]}" \
+        "${NOTES[@]}" \
+        "${ARTIFACTS[@]}"
+fi