cancel_redundant_builds.sh

#!/usr/bin/env bash

# Adapted from this CircleCI community forum post by user 'lumberj'. Adds
# another filter condition to ensure that we're not canceling builds that are
# part of the current workflow (sha check).
#
# https://discuss.circleci.com/t/auto-cancel-redundant-builds-not-working-for-workflow/13852/31

CIRCLE_BASE_URL="https://circleci.com/api/v1.1/project/github/$CIRCLE_PROJECT_USERNAME/$CIRCLE_PROJECT_REPONAME"
QUERY_PARAMS="circle-token=$CIRCLE_TOKEN"

getRunningJobs() {
  local circleApiResponse
  local runningJobs

  circleApiResponse=$(curl --silent --show-error "$CIRCLE_BASE_URL/tree/$CIRCLE_BRANCH?$QUERY_PARAMS" -H "Accept: application/json")
  runningJobs=$(echo "$circleApiResponse" | jq "map(if .status == \"running\" and .vcs_revision != \"${CIRCLE_SHA1}\" then .build_num else \"None\" end) - [\"None\"] | .[]")
  echo "$runningJobs"
}

cancelRunningJobs() {
  local runningJobs
  runningJobs=$(getRunningJobs)
  for buildNum in $runningJobs;
  do
    echo Canceling "$buildNum"
    curl --silent --show-error -X POST "$CIRCLE_BASE_URL/$buildNum/cancel?$QUERY_PARAMS" >/dev/null
  done
}

cancelRunningJobs