fix(devcontainers-cli): add PNPM_HOME for pnpm package manager

[defelmnq]

PNPM requires $PNPM_HOME to be set to install packages.
This PR is a follow-up on the one creating @devcontainers-cli module - to ensure PNPM_HOME is set, based on values set by Coder.

[defelmnq]

Purely testing purpose, done to not rely on NPM.

[defelmnq]

Changed the ordering to use PNPM as a last option, if NPM is installed too.

[defelmnq]

Main part of the fix, adding $PNPM_HOME if not set yet.

[matifali]

Just for my education, how does that work? What is CODER_SCRIPT_BIN_DIR?

[mafredri]

Typically /tmp/coder-script-data/bin, a place where all scripts can place binaries and they will be part of PATH (guaranteed by agent).

[mafredri]

Suggesting a minor improvement to the script but otherwise looks alright.

[mafredri]

This comment could better explain why we need to do this, for posterity.

[mafredri]

Typically /tmp/coder-script-data/bin, a place where all scripts can place binaries and they will be part of PATH (guaranteed by agent).

[mafredri]

It'd be nice to factor out this repetition, might I suggest the following?

install() {
  if [ "$PACKAGE_MANAGER" = "npm" ]; then
    npm install -g @devcontainers/cli
  elif [ "$PACKAGE_MANAGER" = "pnpm" ]; then
    # <reason we set this>
    if [ -z "$PNPM_HOME" ]; then
      PNPM_HOME="$CODER_SCRIPT_BIN_DIR"
      export PNPM_HOME
    fi
    pnpm add -g @devcontainers/cli
  elif [ "$PACKAGE_MANAGER" = "yarn" ]; then
    yarn global add @devcontainers/cli
  fi
}

if ! install; then
  echo "Failed to install @devcontainers/cli" >&2
  exit 1
fi

if ! command -v devcontainer > /dev/null 2>&1; then
  echo "Installation completed but 'devcontainer' command not found in PATH" >&2
  exit 1
fi

echo "🥳 @devcontainers/cli has been installed into $(which devcontainer)!"
exit 0 

Adds a bit more detail and validates the binary is present.

[matifali]

Make version 1.0.1, please, in the README.md

[matifali]

@mafredri for version constraints, I am thinking of introducing labels like version: patch, version: minor, and version: major, and a workflow that checks if the README version has been bumped to match this constraint from the label. This workflow would keep failing unless the required version bump is made.