If you encounter the error Corepack is about to download ... during your CI pipeline setup, it’s likely caused by a cached or mismatched version of pnpm and the absence of a packageManager field in your project. Here’s how to resolve this issue efficiently.

Issue Example:

You might see logs similar to this in your CI pipeline:

#12 [prod 5/7] RUN pnpm fetch --prod
#12 0.353 ! Corepack is about to download https://registry.npmjs.org/pnpm/-/pnpm-9.14.2.tgz
#12 0.972 ! The local project doesn't define a 'packageManager' field. Corepack will now add one referencing ...

This happens because Corepack cannot determine which version of pnpm to use, and it defaults to attempting a download. This behavior disrupts CI workflows.

Root Cause

  1. Missing packageManager Field: Your project doesn’t explicitly define which pnpm version to use.
  2. Corepack Download Prompt: Corepack attempts to download pnpm but requires confirmation, which fails in non-interactive CI environments.
  3. Cached or Outdated pnpm Version: The CI environment might have cached an incompatible pnpm version.

Solution

Add the following steps to your Dockerfile or CI pipeline to ensure a consistent pnpm installation and prevent Corepack from prompting for downloads.

Dockerfile Configuration

# Enable Corepack
RUN corepack enable 

# Install a specific version of pnpm globally
RUN corepack prepare pnpm@9.8.0 --activate

# Disable Corepack download prompts
ENV COREPACK_ENABLE_DOWNLOAD_PROMPT=0

Explanation of Commands

  1. corepack enable: Activates Corepack, enabling it to manage package managers like pnpm.
  2. corepack prepare pnpm@9.8.0 --activate: Installs and globally activates the specified pnpm version.
  3. ENV COREPACK_ENABLE_DOWNLOAD_PROMPT=0: Prevents Corepack from prompting for downloads, making it CI-friendly.

Adding packageManager Field

To prevent the error entirely, add a packageManager field to your package.json:

{
  "name": "your-project",
  "version": "1.0.0",
  "packageManager": "pnpm@9.8.0"
}

This ensures Corepack knows which version of pnpm your project requires.

Examples:

Dockerfile for nodejs application

Here’s a complete Dockerfile example:

FROM node:18-alpine

# Enable Corepack and set pnpm version
RUN corepack enable
RUN corepack prepare pnpm@9.8.0 --activate

# Disable Corepack download prompts
ENV COREPACK_ENABLE_DOWNLOAD_PROMPT=0

# Set work directory
WORKDIR /app

# Copy project files
COPY . .

# Install dependencies and build
RUN pnpm install
RUN pnpm build

Dockerfile for NestJS application

FROM node:20-slim AS base

ENV PNPM_HOME="/pnpm"
ENV PATH="$PNPM_HOME:$PATH"
RUN corepack enable && corepack install --global pnpm@8.15.4
ENV COREPACK_ENABLE_DOWNLOAD_PROMPT=0

FROM base AS prod

WORKDIR /app
COPY package.json /app
COPY tsconfig.json /app
COPY pnpm-lock.yaml /app
RUN pnpm fetch --prod

COPY . /app

# Install nestjs cli
RUN pnpm install -g @nestjs/cli

# Install the dependencies
RUN pnpm install --prod

# Build the nestjs app
RUN pnpm run build

FROM base
COPY --from=prod /app/node_modules /app/node_modules
COPY --from=prod /app/dist /app/dist
COPY --from=prod /app/package.json /app/package.json
COPY --from=prod /app/pnpm-lock.yaml /app/pnpm-lock.yaml
COPY --from=prod /app/tsconfig.json /app/tsconfig.json
WORKDIR /app

EXPOSE 3000
CMD [ "pnpm", "start" ]

Verifying in CI

  • Check that pnpm is installed with the correct version by running: pnpm --version
  • Ensure your pipeline passes without prompting for Corepack downloads.

By following these steps, you can avoid errors related to pnpm installation in CI environments and maintain a smooth workflow.