How can I avoid reinstalling PNPM in every step of my Cloud Build pipeline?

Each step in Cloud Build runs in its own container, so environment modifications (like installing pnpm globally) persist only for the duration of that step. Therefore, if you install pnpm in one step, it won’t be available in the next unless you install it again.

Alternatives

1. Use a Custom Docker Image

Build a custom Docker image that includes Node.js and pnpm preinstalled. Then use that image for your build steps. This way, every step that uses that image will have pnpm available without having to install it each time.

Example Dockerfile:

DOCKERFILECopied
FROM node:16
RUN npm install -g pnpm@<version>
WORKDIR /app

Then, in your Cloud Build configuration:

YAMLCopied
steps:
  - id: 'Install dependencies'
    name: 'gcr.io/your-project/custom-node-image'
    entrypoint: 'bash'
    args:
      - "-c"
      - |
        pnpm install
  - id: 'Run tests'
    name: 'gcr.io/your-project/custom-node-image'
    entrypoint: 'bash'
    args:
      - "-c"
      - |
        pnpm run test

2. Combine Steps in a Single Container

If it fits your CI workflow, combine multiple commands into a single step to avoid having to reinstall pnpm. However, this reduces modularity since all commands will run in the same container instance.

Example:

YAMLCopied
steps:
  - id: 'Build and Test'
    name: ${_NODE_VERSION}
    entrypoint: 'bash'
    args:
      - "-c"
      - |
        npm install -g ${_PNPM_VERSION}
        pnpm install
        pnpm run test

3. Use Cloud Build Caches (Limited)

Cloud Build offers caching mechanisms, but caching mainly targets dependencies (like node_modules) rather than tool installations. While you can cache pnpm’s installation, you still need to ensure that it’s available in the container’s PATH for every step.

Conclusion

The recommended approach is to create a custom Docker image with pnpm preinstalled. This avoids repeated installations in each step and leads to a cleaner, faster CI pipeline.