add cancelot script for gcloud, source: https://gist.github.com/siber…

…ex/bb0540b208019382d08732cc6dd59007

story: GoogleCloudPlatform/cloud-builders-community#386 (comment)
(cherry picked from commit 99dd23b3d0c79564f7e7ea18bd31d7192fdd33a4)

gcloud/cancelot.sh

@@ -0,0 +1,111 @@
+#!/usr/bin/env bash
+# https://gist.github.com/siberex/bb0540b208019382d08732cc6dd59007
+
+# Provides automation for cancelling Cloud Builds
+# Use as a first step to cancel previous builds currently in progress or queued for the same branch name and trigger id.
+# Similar to: https://github.com/GoogleCloudPlatform/cloud-builders-community/tree/master/cancelot
+
+# Usage: cancelot.sh --current_build_id $BUILD_ID --branch_name $BRANCH_NAME --same_trigger_only
+# Usage within Cloud Build step:
+#    steps:
+#    - name: 'gcr.io/cloud-builders/gcloud-slim:latest'
+#      entrypoint: 'bash'
+#      args: ['./cancelot.sh', '--current_build_id', '$BUILD_ID', '--same_trigger_only']
+
+# Exit script when command fails
+set -o errexit
+# Return value of a pipeline is the value of the last (rightmost) command to exit with a non-zero status
+set -o pipefail
+
+# Note: GitHub App builds DOES NOT contain Source.RepoSource.Revision.BranchName field.
+# The actual source for GitHub repo will be storageSource.bucket, check actual source with:
+# $ gcloud builds describe $BUILD_ID --format=json
+
+# We still could use substitutions.BRANCH_NAME
+# https://cloud.google.com/cloud-build/docs/configuring-builds/substitute-variable-values
+
+CMDNAME=${0##*/}
+echoerr() { echo "$@" 1>&2; }
+
+usage() {
+    cat <<USAGE >&2
+Usage:
+    $CMDNAME --current_build_id \$BUILD_ID [--branch_name \$BRANCH_NAME] [--same_trigger_only]
+    --current_build_id \$BUILD_ID  Current Build Id
+    --branch_name \$BRANCH_NAME    Trigger branch (aka head branch)
+                                    (optional, defaults to current build substitutions.BRANCH_NAME)
+    --same_trigger_only           Only cancel builds with the same Trigger Id as current build’s trigger id
+                                    (optional, defaults to false = cancel all matching branch)
+USAGE
+    exit 1
+}
+
+SAME_TRIGGER_ONLY=0
+
+# Process arguments
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+    --current_build_id)
+        CURRENT_BUILD_ID="$2"
+        if [[ $CURRENT_BUILD_ID == "" ]]; then break; fi
+        shift 2
+        ;;
+    --branch_name)
+        TARGET_BRANCH="$2"
+        shift 2
+        ;;
+    --same_trigger_only)
+        SAME_TRIGGER_ONLY=1
+        shift 1
+        ;;
+    --help)
+        usage
+        ;;
+    *)
+        echoerr "Unknown argument: $1"
+        usage
+        ;;
+    esac
+done
+
+if [[ "$CURRENT_BUILD_ID" == "" ]]; then
+    echo "Error: you need to provide Build Id"
+    usage
+fi
+
+QUERY_BUILD=$(gcloud builds describe "$CURRENT_BUILD_ID" --format="value(buildTriggerId, startTime, substitutions.BRANCH_NAME)")
+read -r BUILD_TRIGGER_ID BUILD_START_TIME BUILD_BRANCH <<<"$QUERY_BUILD"
+
+FILTERS="id!=$CURRENT_BUILD_ID AND startTime<$BUILD_START_TIME"
+
+if [[ "$TARGET_BRANCH" == "" ]]; then
+    TARGET_BRANCH="$BUILD_BRANCH"
+fi
+FILTERS="$FILTERS AND substitutions.BRANCH_NAME=$TARGET_BRANCH"
+
+if [[ $SAME_TRIGGER_ONLY -eq 1 ]]; then
+    # Get Trigger Id from current build
+    FILTERS="$FILTERS AND buildTriggerId=$BUILD_TRIGGER_ID"
+    echo "Filtering Trigger Id: $BUILD_TRIGGER_ID"
+fi
+
+echo "Filtering ongoing builds for branch '$TARGET_BRANCH' started before: $BUILD_START_TIME"
+# echo "$FILTERS"
+
+# Get ongoing build ids to cancel (+status)
+while IFS=$'\n' read -r line; do CANCEL_BUILDS+=("$line"); done < <(gcloud builds list --ongoing --filter="$FILTERS" --format="value(id, status)")
+
+BUILDS_COUNT=${#CANCEL_BUILDS[@]}
+echo "Found $BUILDS_COUNT builds to cancel"
+if [[ $BUILDS_COUNT -eq 0 ]]; then
+    exit 0
+fi
+
+# Cancel builds one by one to get output for each
+# printf '%s\n' "${CANCEL_BUILDS[@]}"
+echo "BUILD ID                                CURRENT STATUS"
+for build in "${CANCEL_BUILDS[@]}"; do
+    echo "$build"
+    ID=$(echo "$build" | awk '{print $1;}')
+    gcloud builds cancel "$ID" || true
+done