Custom (or latest) npm version in Google Cloud Builder - npm

Question

I'm using Google Cloud Builder (GCB) to build some Node.js code. I'm using npm's new package-lock.json feature to pin dependencies. This works best when using the npm ci command that was introduced in npm#5.7.1. Unfortunately, all of GCB's npm images are currently set to npm#5.6.0
How can I use a different npm version in GCB without creating a custom builder image?
Edit: It may not be the case that all of GCB's images are set to npm#5.6.0, but the one that I need to use (node-8.11.0) is set to this version.

Answer 1

I solved the issue by creating my own container image based on the cloud-builder's npm image.
Dockerfile:
FROM gcr.io/cloud-builders/npm:node-8.11.0
ARG NPM_VERSION
RUN npm i -g npm#${NPM_VERSION}
ENTRYPOINT ["npm"]
cloudbuild.yaml:
steps:
- name: 'gcr.io/cloud-builders/docker'
args:
- 'build'
- '--build-arg=NPM_VERSION=latest'
- '--tag=gcr.io/$PROJECT_ID/npm:latest'
- '.'
images:
- 'gcr.io/$PROJECT_ID/npm:latest'
I ran gcloud builds submit . --config=cloudbuild.yaml from the same folder containing the Dockerfile and cloudbuild.yaml files. This submitted the build to GCB and posted an image in my project's container registry. I then used this image in my other project's cloudbuild.yaml that needed the upgraded npm version, like so:
steps:
- id: frontend_install
name: 'gcr.io/$PROJECT_ID/npm:latest'
args: ['ci']
waitFor: ['-']
After doing this, everything works as expected.