Test in CI with Cua sandboxes

The cua-sandbox action creates a sandbox from any image, waits until it is ready, runs your tests against it, uploads logs, the doctor report and a screenshot, and always deletes it, even when the job is cancelled. Every step is a plain cua command, so the same run works on your machine.

GitHub Actions#

jobs:
  e2e:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@1.97.1
      - id: sandbox
        uses: trycua/cua/.github/actions/cua-sandbox@main
        with:
          image: linux
          run: |
            cua sb exec "$CUA_SANDBOX" uname -a
            cua sb screenshot "$CUA_SANDBOX" -o "$CUA_SANDBOX_ARTIFACTS/desktop.png"

• image: a canonical image, a bench image or any registry reference.
• on: local (the default: Docker on the runner, or QEMU with KVM for VM images) or cloud. Cloud needs CUA_CLIENT_ID and CUA_CLIENT_SECRET in the job env. claim-ttl (default 60m) is the backstop if cleanup never runs.
• run runs on the runner with CUA_SANDBOX set to the sandbox ref. guest-run runs inside the sandbox. guest-setup runs as root inside it first, for example to install test dependencies.
• cua-version: source (the default) builds the CLI from the action's ref. Pass cua-bin to use one you built.
• Outputs: ref, name, env-url, viewer-url, urls, overlays, doctor-status, artifacts-dir.

Test the code you just built#

An image bundles its own cua-spacesd, and runners may have their own cua-driver installed. To test your build instead, inject it with overlay:

      - uses: trycua/cua/.github/actions/cua-sandbox@main
        with:
          image: linux
          overlay: |
            cua-spacesd=target/release/cua-spacesd
            cua-driver=target/release/cua-driver
          expect: cua-driver=git:${{ github.sha }}
          run: ./tests/e2e.sh

Each overlay replaces the guest file atomically, is recorded with its sha256 and restarts what runs it. The action then runs cua doctor with an expectation per overlay. The job fails before your tests run if anything else runs, for example a daemon that was never restarted or a file replaced afterwards. On the runner, PATH resolves cua-driver to the injected build only, so a copy installed on the runner is never used.

The same steps with the CLI#

cua sb create linux --name ci --wait desktop \
  --overlay cua-driver=./target/release/cua-driver --json
cua doctor local:ci --no-host --only build \
  --expect cua-driver=sha256:<sha256 printed by create>
cua sb exec local:ci uname -a
cua sb rm local:ci --force

--overlay also works on a running sandbox (cua sb overlay ci cua-driver=PATH) and for any file: NAME=PATH:/guest/path.

From Python, pass overlay= to Sandbox.create, or call sb.overlay(...) on a running sandbox. cua-driver and cua-spacesd find their guest path; any other file takes (path, "/guest/path"). If an overlay fails, the new sandbox is deleted and the error raised:

import os
import tempfile
 
from cua_sandbox import Image, Sandbox
 
tool = os.path.join(tempfile.mkdtemp(), "tool")
with open(tool, "w") as f:
    f.write("#!/bin/sh\necho build-under-test\n")
os.chmod(tool, 0o755)
 
sb = await Sandbox.create(
    Image.from_registry("python:3.12-slim"),
    command=["sleep", "infinity"],
    runtime="runc",
    local=True,
    overlay={"tool": (tool, "/usr/local/bin/tool")},
)
[result] = await sb.overlay({"tool": (tool, "/usr/local/bin/tool")})
print(result.name, result.target, result.sha256)
await sb.destroy()

The Rust, TypeScript, Swift and Kotlin SDKs have the same overlays create option and overlay method.

The action's steps are phases of .github/actions/cua-sandbox/cua-sandbox.sh, which also runs outside GitHub. Set the inputs as CUA_SB_* environment variables (for example CUA_SB_IMAGE, CUA_SB_OVERLAY and CUA_SB_RUN) and run cua-sandbox.sh all. It cleans up on exit and on Ctrl-C.

Expectations#

cua doctor REF --expect COMPONENT=WANT fails unless that exact build runs. WANT is one of:

• sha256:<hex>: the executable.
• git:<sha>: the source revision it was built from.
• a version.

Components are cua-spacesd, cua-driver or an overlay name. Inside the sandbox, cua-spacesd doctor --expect ... does the same.