cloudbuild.yaml

steps:
  # To test locally, first uncomment the last two lines of this comment block, then submit with:
  #
  #    gcloud builds submit --config cloudbuild.yaml .

  - name: 'gcr.io/cloud-builders/docker'
    args: ['build', '.']
    timeout: 7200s

timeout: 7200s
options:
  env: # https://bugs.chromium.org/p/chromium/issues/detail?id=993053#c3
    - 'VPYTHON_VIRTUALENV_ROOT=/workspace/__cache'
    - 'CIPD_CACHE_DIR=/workspace/__cache'

Dockerfile

FROM debian:testing-slim
RUN apt-get update && apt-get upgrade -y && apt-get install -y \
  git \
  python \
  curl

RUN mkdir -p --mode=0777 /workspace/__cache \
  && groupadd -g 2000 skia \
  && useradd -u 2000 -g 2000 --home /workspace/__cache skia

ENV VPYTHON_VIRTUALENV_ROOT /workspace/__cache
ENV CIPD_CACHE_DIR /workspace/__cache

USER skia

RUN printenv \
  && cd /tmp \
  && git clone 'https://chromium.googlesource.com/chromium/tools/depot_tools.git' \
  && mkdir -p /tmp/skia \
  && cd /tmp/skia \
  && export PATH=$PATH:/tmp/depot_tools \
  && touch noop.py \
  && vpython noop.py \
  && ls -al /tmp/depot_tools \
  && /tmp/depot_tools/fetch skia \
  && ls -al /workspace/__cache \
  && printenv