gcpctx 0.1.0

Directory-scoped Google Cloud service account impersonation contexts

gcpctx

Directory-scoped Google Cloud service account impersonation contexts for terminals, IDEs, and coding agents.

What is gcpctx?

gcpctx automatically activates an isolated Google Cloud SDK and Application Default Credentials (ADC) environment when you enter a directory with a .gcpctx.toml file. Each profile maps to a GCP project and an impersonated service account. Activation exports a dedicated CLOUDSDK_CONFIG so your global ~/.config/gcloud is never mutated.

Why directory-scoped impersonation?

Developers and coding agents often inherit broad or wrong GCP credentials from the parent shell. gcpctx scopes authentication to the repository you are working in, with first-use approval and config-hash invalidation when trust-relevant settings change.

Installation

Choose one of these options:

Method	Best for
uvx	Try without installing, CI one-offs, pinned versions
pipx	Daily CLI use on your machine
From source	Contributing or unreleased builds

Run with uvx (no install)

uvx runs gcpctx in an ephemeral environment—no global install required.

# Latest from PyPI (when published)
uvx gcpctx --help

# Pin a version
uvx gcpctx@0.1.0 status

# Run from a local checkout (before publish)
uvx --from /path/to/gcpctx gcpctx --help

Typical workflow with uvx:

cd my-repo
uvx gcpctx init-project \
  --project my-dev-project \
  --service-account [e-mail]

uvx gcpctx approve
eval "$(uvx gcpctx activate --shell zsh)"

uvx gcpctx status
uvx gcpctx doctor

Shell hooks installed via gcpctx init zsh call gcpctx on your PATH. After choosing uvx, either add a shell alias (alias gcpctx='uvx gcpctx') or install with pipx / uv tool install for hook integration.

pipx

pipx install gcpctx
gcpctx --help

From source

git clone <repo-url> && cd gcpctx
uv sync
uv run gcpctx --help
# optional: uv tool install -e .

Quick start

# 1. Create project config
gcpctx init-project --project my-dev-project \
  --service-account [e-mail]

# 2. Approve and activate (zsh example)
gcpctx approve
eval "$(gcpctx activate --shell zsh)"

# 3. Verify
gcpctx status
gcloud config list

.gcpctx.toml example

version = 1
default_profile = "dev"

[profiles.dev]
project = "my-dev-project"
service_account = "[e-mail]"
quota_project = "my-billing-project"
region = "asia-northeast1"

Shell integration

gcpctx init zsh   # or: gcpctx init bash
exec $SHELL       # reload shell

The hook runs gcpctx hook eval on every directory change. Stdout is shell code only; diagnostics go to stderr.

Manual activation without hooks:

eval "$(gcpctx activate --shell zsh)"
eval "$(gcpctx deactivate --shell zsh)"  # restore prior env

Switch profile (after gcpctx init installs the wrapper):

gcpctx-use prod-readonly

IDE usage (VS Code, Cursor, JetBrains)

Integrated terminals inherit the parent shell environment. Subprocesses started by the IDE (build tasks, debuggers, test runners) see the same CLOUDSDK_CONFIG, ADC, and GCPCTX_* variables as your shell.

Recommended setup

1. Install shell hooks (gcpctx init zsh) or manually eval "$(gcpctx activate --shell zsh)" in your login shell.
2. Open the IDE from that shell (cursor ., code .) so new integrated terminals start activated.
3. Confirm with gcpctx status in an integrated terminal.

Verify isolation

gcpctx status
gcpctx doctor
gcpctx doctor --json   # machine-readable for scripts

Doctor checks that CLOUDSDK_CONFIG lives under ~/.cache/gcpctx/contexts/, gcloud project/impersonation match your profile, and ADC is initialized.

GOOGLE_APPLICATION_CREDENTIALS

In hook mode, GOOGLE_APPLICATION_CREDENTIALS is unset while active (previous value restored on deactivate) so ADC impersonation is not overridden. If you must keep a key file in non-interactive sessions, pass --allow-google-application-credentials to activate.

Coding agents (Cursor, Claude Code, Codex, Copilot)

Agents run in terminals or sandboxes that inherit environment variables. Use either shell activation (whole session) or gcpctx run (one process only).

Process-scoped launch (recommended for agents)

Run a command with per-project credentials without changing your parent shell:

gcpctx approve
gcpctx run -- claude
uvx gcpctx run -- codex ...
gcpctx run --profile dev -- gcloud storage ls

• Requires .gcpctx.toml in the current directory tree (exit 2 if missing).
• Pre-approve for non-interactive terminals (gcpctx approve).
• GOOGLE_APPLICATION_CREDENTIALS is unset in the child by default (same as hook mode).
• Access tokens are short-lived; client libraries refresh ADC automatically (no gcpctx supervisor).

Shell activation (whole session)

1. Add .gcpctx.toml to the repo (gcpctx init-project).

2. Approve once interactively, or pre-approve for automation:

   gcpctx approve   # remembered approval for this directory/profile
   

3. Activate in the shell that launches the agent:

   eval "$(gcpctx activate --shell zsh)"
   

4. Agents and their subprocesses inherit isolated credentials.

Non-interactive / fail-closed

Without a matching approval, gcpctx activate exits with code 3 in non-interactive mode (typical agent terminals). Pre-run gcpctx approve in CI or document that users must activate interactively once.

Agent-friendly diagnostics

gcpctx doctor --json
gcpctx status --json

Parse JSON for active, cloudsdk_config, approval, and per-check status from doctor.

When GOOGLE_APPLICATION_CREDENTIALS is required

Some tools insist on a key file path. Use --allow-google-application-credentials only when necessary; prefer impersonated ADC otherwise.

Security model

• First-use approval with optional remember; non-interactive mode fails closed without approval
• Config SHA-256 binding invalidates approval when project, service account, or config changes
• Isolated CLOUDSDK_CONFIG under ~/.cache/gcpctx/contexts/
• Service account impersonation only (no long-lived key files in repo config)
• Restrictive file permissions on state directories and approvals
• GOOGLE_APPLICATION_CREDENTIALS unset by default in hook mode (restored on deactivate)

See Architecture decision records for design rationale (ADR-0003 through ADR-0008).

Troubleshooting

Symptom	Fix
approval required in CI/agent	Run gcpctx approve once, or activate interactively
Wrong project	gcpctx status; check .gcpctx.toml
Stale credentials	gcpctx refresh or gcpctx reset
gcloud not found	Install Google Cloud SDK
ADC issues	gcpctx doctor
IDE terminal not activated	Activate in parent shell before launching IDE, or use shell hooks

Contributing

See CONTRIBUTING.md for developer setup, tests, and architecture notes.