Add Kokoro build script for merging main into chromeos

The Kokoro build script sets up access to the chromium
gerrit, creates the merge commit and uploads it.

BUG=b:209034086
TEST=./ci/kokoro/simulate merge-to-chromeos.sh

Change-Id: Ia686b937c3d6b0b744d5c2162eb2847c5952e977
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3318793
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Dennis Kempin <denniskempin@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>

ci/kokoro/merge-into-chromeos.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+set -e
+cd "${KOKORO_ARTIFACTS_DIR}/git/crosvm"
+
+ORIGIN=https://chromium.googlesource.com/chromiumos/platform/crosvm
+RETRIES=3
+
+gerrit_prerequisites() {
+    set -e
+
+    # Authenticate to GoB if we don't already have a cookie.
+    # This should only happen when running in Kokoro, not locally.
+    # See: go/gob-gce
+    if [[ -z $(git config http.cookiefile) ]]; then
+        git clone https://gerrit.googlesource.com/gcompute-tools \
+            "${KOKORO_ARTIFACTS_DIR}/gcompute-tools"
+        "${KOKORO_ARTIFACTS_DIR}/gcompute-tools/git-cookie-authdaemon" --no-fork
+    fi
+
+    # We cannot use the original origin that kokoro used, as we no longer have
+    # access the GoB host via rpc://.
+    git remote remove origin
+    git remote add origin ${ORIGIN}
+    git fetch -q origin
+
+    # Set up gerrit Change-Id hook.
+    mkdir -p .git/hooks
+    curl -Lo .git/hooks/commit-msg \
+        https://gerrit-review.googlesource.com/tools/hooks/commit-msg
+    chmod +x .git/hooks/commit-msg
+}
+
+upload() {
+    # Try uploading to gerrit. Retry due to errors on first upload.
+    # See: b/209031134
+    for i in $(seq 1 $RETRIES); do
+        echo "Push attempt $i"
+        if git push origin HEAD:refs/for/chromeos; then
+            return 0
+        fi
+    done
+    return 1
+}
+
+main() {
+    set -e
+    gerrit_prerequisites
+
+    # Perform merge on a tracking branch.
+    git checkout -b chromeos
+    git branch --set-upstream-to origin/chromeos chromeos
+    ./tools/chromeos/create_merge
+
+    upload
+}
+main

tools/chromeos/create_merge

@@ -15,26 +15,25 @@
 # To merge with a specific commit, use: ./tools/chromeos/create_merge $SHA
 
 set -e
-
 cd "$(dirname "${BASH_SOURCE[0]}")/../../" || exit
 
-ORIGIN="$(git remote get-url cros)"
-MERGE_TARGET="${1:-cros/main}"
+LOCAL_BRANCH=$(git branch --show-current)
+REMOTE_NAME=$(git config "branch.${LOCAL_BRANCH}.remote")
+URL=$(git remote get-url "${REMOTE_NAME}")
+
+DEFAULT_TARGET="${REMOTE_NAME}/main"
+MERGE_TARGET="${1:-${DEFAULT_TARGET}}"
 
 commit_list() {
     git log --oneline --decorate=no --no-color "HEAD..${MERGE_TARGET}"
 }
 
 prerequisites() {
-    if [[ -e "${ORIGIN}" ]]; then
-        echo "'cros' remote does not exist."
-        echo "Are you running this in a ChromeOS checkout?"
-        exit 1
-    fi
-
-    local tracking="$(git rev-parse --abbrev-ref --symbolic-full-name @{u})"
-    if [[ "${tracking}" != "cros/chromeos" ]]; then
-        echo "Not tracking the cros/chromeos branch."
+    if [[ -e "${LOCAL_BRANCH}" ]] ||
+        [[ -e "${REMOTE_NAME}" ]] ||
+        [[ -e "${URL}" ]]; then
+        echo "This script requires the local repository to be on" \
+            "a tracking branch."
         exit 1
     fi
 
@@ -55,11 +54,11 @@ merge_message() {
     local new=$(git rev-parse "${MERGE_TARGET}")
     local count=$(commit_list | wc -l)
 
-    echo "Merge ${count} commits from ${MERGE_TARGET}"
+    echo "Merge ${count} commits from ${MERGE_TARGET} ($(date +%F))"
     echo ""
     commit_list
     echo ""
-    echo "${ORIGIN}/+log/${old}..${new}"
+    echo "${URL}/+log/${old}..${new}"
     echo ""
     echo "BUG=None"
     echo "TEST=CQ"
@@ -68,7 +67,7 @@ merge_message() {
 main() {
     prerequisites
     git merge --no-ff "${MERGE_TARGET}" -m "$(merge_message)"
-    git log -n 1
+    git --no-pager log -n 1
 }
 
 main