A small script to run as part of your bitbucket pipelines to deploy code from the Bitbucket repository into an external git repository, tested with Acquia so far. Configure SSH keys and the DEPLOY_URL variable in the BitBucket UI to make it work. Assumes a Drupal install in /docroot and node stuff in /app

bitbucket-pipelines.yml

image: node:7.4

# Yes, you do need this in order to be able to do onward pushes.
clone:
  depth: full

pipelines:
  default:
  # Don't forget caches as well.
    - step:
        script:
          - ENVIRONMENT=prod make build
          - ENVIRONMENT=prod make deploy
  # Tags don't run on the `default` pipeline so they need one for themselves.
  tags:
    '*':
      - step:
          script:
            - ENVIRONMENT=prod make build
            - ENVIRONMENT=prod make deploy

deploy.sh

#!/bin/bash
set -x
set -e

if [ -n "${BITBUCKET_REPO_SLUG}" ] ; then

    git config user.email "bitbucket@example.com"
    git config user.name "Bitbucket Pipelines"

    git remote add deploy $DEPLOY_URL;

    # If the module is -dev, a .git file comes down.
    find docroot -type d -name .git -exec rm -rf {} \;

    SHA=$(git rev-parse HEAD)
    GIT_MESSAGE="Deploying ${SHA}: $(git log -1 --pretty=%B)"

    git add --force --all

    # Exclusions:
    git reset -- app/node_modules
    git status
    git commit -qm "${GIT_MESSAGE}"

    if [ $BITBUCKET_TAG ];
      then
        git tag --force -m "Deploying tag: ${BITBUCKET_TAG}" ${BITBUCKET_TAG}
        git push deploy refs/tags/${BITBUCKET_TAG}
    fi;

    if [ $BITBUCKET_BRANCH ];
      then
        git push deploy --force refs/heads/$BITBUCKET_BRANCH;
    fi;

    git reset --mixed $SHA;
fi;