dagger-ci

name	dagger-ci
description	Running CI locally with Dagger

Dagger CI

Dagger docs: dagger.io · Go SDK CI config: ../../../dagger/ · GitHub Actions: .github/workflows/test.yml

Motivation

Running builds and test suites locally is a great start to making sure software works. But "we can't deploy your machine", and can't trust that the tests run locally didn't accidentally rely on unexpected side effects (e.g. a new dependency that didn't make it into version control).

CI workflows fix that (this project uses Github Actions), but then when CI fails it is incredibly hard/slow to debug.

Dagger allows us to run the full CI workflow locally (our Github Actions just point to Dagger) and iterate faster. Now Dagger can be trusted to create a fully reproducible build that is known to work.

What Dagger Does

Dagger runs the full CI pipeline inside a container for reproducibility. It:

1. Installs Node and PNPM in a Debian container
   • Versions are hardcoded, and should match this devcontainer's setting.
2. Copies source, installs dependencies (pnpm i)
3. Runs nx run-many -t build (all packages)
4. In parallel:
   • Runs nx run-many -t test + nx run-many -t coverage-report (test + coverage)
   • Runs nx run @leyman/main:lifecycle (validates lifecycle config is up to date)

If Dagger passes, CI passes.

Running Locally

# Full CI simulation (same as GitHub Actions)
dagger-test
# PATH based reference to scripts/commands/dagger-test

# Set up Dagger for development (initializes module dependencies)
dagger-develop
# PATH based reference to scripts/commands/dagger-develop

Tip: Run test-ci first — Much faster for iteration. Use Dagger only to confirm the final result before push. Dagger is also much harder to debug directly (but still easier than cloud CI)

Dagger Cloud (Optional)

dagger login # connect to Dagger Cloud for pipeline visualization and caching

With Dagger Cloud, you get a web UI showing each pipeline step and its logs, which is useful for debugging CI failures.

Module Structure

dagger/
├── test-and-build/    ← main CI module (Go)
│   ├── main.go        ← pipeline definition
│   └── dagger.json
└── modules/
    ├── node/          ← Node.js installation
    ├── pnpm/          ← PNPM installation
    └── debian/        ← base Debian container

When to Use Dagger vs Nx

Use	When
test-only	During development — fast feedback, uses local cache
dagger-test	Before pushing — confirms full CI will pass
test-ci	Middle ground — runs full tests + coverage without containerization

Versions

• Dagger engine: Similar to Node/PNPM, should match version of Dockerfile

These are set in dagger/test-and-build/main.go. When upgrading, update both the Go source and the dagger.json engine version.

Troubleshooting

Container fails but Nx passes — likely an environment difference (missing binary, wrong Node version, network issue). Check the Dagger logs carefully for the specific step that failed.

"dagger: command not found" — Dagger CLI must be installed. In the DevContainer it is available automatically.

Slow first run — Dagger downloads and caches container layers on the first run. Subsequent runs use the cache.