Dagger

Programmable CI/CD engine that runs pipelines in containers using Go, Python, or TypeScript SDKs.

Installation

CLI Installation

Command	Description
`curl -fsSL https://dl.dagger.io/dagger/install.sh \| sh`	Install Dagger CLI on Linux/macOS
`brew install dagger/tap/dagger`	Install on macOS with Homebrew
`choco install dagger`	Install on Windows with Chocolatey
`scoop install dagger`	Install on Windows with Scoop
`nix profile install nixpkgs#dagger`	Install on NixOS/with Nix
`dagger version`	Show installed Dagger version

Module Initialization

Command	Description
`dagger init`	Initialize a new Dagger module
`dagger init --sdk=python`	Initialize module with Python SDK
`dagger init --sdk=typescript`	Initialize module with TypeScript SDK
`dagger init --sdk=go`	Initialize module with Go SDK
`dagger init --name=my-pipeline`	Initialize module with custom name
`dagger init --sdk=go --source=./ci`	Initialize in a subdirectory

CLI Commands

Core Operations

Command	Description
`dagger call`	Call a function from the current module
`dagger call build`	Call the build function
`dagger call test --source=.`	Call test function with source argument
`dagger call build --source=. export --path=./dist`	Build and export output locally
`dagger call lint --source=. stdout`	Run lint and print stdout
`dagger call publish --source=. --tag=v1.0`	Call publish function with tag
`dagger functions`	List available functions in module
`dagger shell`	Open interactive Dagger shell
`dagger query`	Execute raw GraphQL query against engine
`dagger run cmd`	Run command inside Dagger session

Authentication and Cloud

Command	Description
`dagger login`	Authenticate with Dagger Cloud
`dagger logout`	Remove authentication
`dagger config`	Display module configuration
`dagger cloud traces`	View pipeline traces in Dagger Cloud
`DAGGER_CLOUD_TOKEN=token dagger call build`	Run with Dagger Cloud token

Module Management

Dependencies

Command	Description
`dagger install github.com/org/repo`	Install a dependency module
`dagger install github.com/org/repo@v1.0`	Install specific version
`dagger install github.com/org/repo/subpath`	Install module from subdirectory
`dagger develop`	Generate/update SDK bindings
`dagger develop --sdk=python`	Switch module to different SDK
`dagger mod sync`	Synchronize module dependencies
`dagger mod update`	Update module dependencies
`dagger publish ttl.sh/my-module`	Publish module to registry
`dagger publish ghcr.io/org/module:v1.0`	Publish to GitHub Container Registry

Pipeline Development (Go)

Container Operations

Command	Description
`func (m MyModule) Build(ctx context.Context, src dagger.Directory) *dagger.Container`	Define build function
`dag.Container().From("golang:1.22")`	Create container from image
`container.WithDirectory("/src", src)`	Mount directory into container
`container.WithExec([]string{"go", "build", "."})`	Execute command in container
`container.WithEnvVariable("KEY", "value")`	Set environment variable
`container.File("/app/binary")`	Get file from container
`container.Directory("/app/dist")`	Get directory from container
`container.WithServiceBinding("db", dbSvc)`	Bind service dependency
`container.WithWorkdir("/src")`	Set working directory
`container.WithUser("nonroot")`	Set container user
`container.Publish(ctx, "ttl.sh/my-image")`	Publish container as image
`container.Export(ctx, "./output.tar")`	Export container as tarball

Go Pipeline Example

package main

import (
	"context"
	"dagger/my-pipeline/internal/dagger"
)

type MyPipeline struct{}

func (m *MyPipeline) Build(ctx context.Context, src *dagger.Directory) *dagger.Container {
	goCache := dag.CacheVolume("go-mod")
	buildCache := dag.CacheVolume("go-build")

	return dag.Container().
		From("golang:1.22-alpine").
		WithMountedCache("/go/pkg/mod", goCache).
		WithMountedCache("/root/.cache/go-build", buildCache).
		WithDirectory("/src", src).
		WithWorkdir("/src").
		WithExec([]string{"go", "mod", "download"}).
		WithExec([]string{"go", "build", "-o", "/app/server", "./cmd/server"})
}

func (m *MyPipeline) Test(ctx context.Context, src *dagger.Directory) (string, error) {
	return m.Build(ctx, src).
		WithExec([]string{"go", "test", "-v", "./..."}).
		Stdout(ctx)
}

func (m *MyPipeline) Publish(ctx context.Context, src *dagger.Directory, tag string) (string, error) {
	build := m.Build(ctx, src)
	return dag.Container().
		From("cgr.dev/chainguard/static:latest").
		WithFile("/app/server", build.File("/app/server")).
		WithEntrypoint([]string{"/app/server"}).
		Publish(ctx, "ttl.sh/my-app:"+tag)
}

Pipeline Development (Python)

Container Operations

Command	Description
`@function`	Decorate function to expose to Dagger
`async def build(self, src: dagger.Directory) -> dagger.Container`	Define async build function
`dag.container().from_("python:3.12")`	Create container from image
`container.with_directory("/src", src)`	Mount directory
`container.with_exec(["pip", "install", "-r", "requirements.txt"])`	Run pip install
`await container.stdout()`	Get command output
`container.with_workdir("/app")`	Set working directory
`container.with_user("nonroot")`	Set container user
`await container.publish("ttl.sh/my-app")`	Publish container as image

Python Pipeline Example

import dagger
from dagger import dag, function, object_type

@object_type
class MyPipeline:
    @function
    async def build(self, src: dagger.Directory) -> dagger.Container:
        pip_cache = dag.cache_volume("pip")
        return (
            dag.container()
            .from_("python:3.12-slim")
            .with_mounted_cache("/root/.cache/pip", pip_cache)
            .with_directory("/app", src)
            .with_workdir("/app")
            .with_exec(["pip", "install", "--no-cache-dir", "-r", "requirements.txt"])
            .with_exec(["pip", "install", "."])
        )

    @function
    async def test(self, src: dagger.Directory) -> str:
        return await (
            self.build(src)
            .with_exec(["pytest", "-v", "--tb=short"])
            .stdout()
        )

    @function
    async def lint(self, src: dagger.Directory) -> str:
        return await (
            self.build(src)
            .with_exec(["ruff", "check", "."])
            .stdout()
        )

    @function
    async def publish(self, src: dagger.Directory, tag: str) -> str:
        build = self.build(src)
        return await (
            dag.container()
            .from_("cgr.dev/chainguard/python:latest")
            .with_directory("/app", build.directory("/app"))
            .with_entrypoint(["python", "-m", "myapp"])
            .publish(f"ttl.sh/my-python-app:{tag}")
        )

Pipeline Development (TypeScript)

TypeScript Pipeline Example

import { dag, Container, Directory, object, func } from "@dagger.io/dagger"

@object()
class MyPipeline {
  @func()
  build(src: Directory): Container {
    const nodeCache = dag.cacheVolume("node-modules")
    return dag
      .container()
      .from("node:20-slim")
      .withMountedCache("/app/node_modules", nodeCache)
      .withDirectory("/app", src)
      .withWorkdir("/app")
      .withExec(["npm", "ci"])
      .withExec(["npm", "run", "build"])
  }

  @func()
  async test(src: Directory): Promise<string> {
    return this.build(src)
      .withExec(["npm", "test"])
      .stdout()
  }

  @func()
  async lint(src: Directory): Promise<string> {
    return this.build(src)
      .withExec(["npm", "run", "lint"])
      .stdout()
  }

  @func()
  async publish(src: Directory, tag: string): Promise<string> {
    return dag
      .container()
      .from("cgr.dev/chainguard/node:latest")
      .withDirectory("/app", this.build(src).directory("/app/dist"))
      .withEntrypoint(["node", "/app/index.js"])
      .publish(`ttl.sh/my-node-app:${tag}`)
  }
}

Caching

Cache Volumes

Command	Description
`container.WithMountedCache("/go/pkg", dag.CacheVolume("gomod"))`	Mount persistent cache volume (Go)
`container.with_mounted_cache("/root/.cache/pip", dag.cache_volume("pip"))`	Mount pip cache (Python)
`dag.CacheVolume("node-modules")`	Create named cache volume
`container.WithMountedCache("/root/.cache/go-build", dag.CacheVolume("gobuild"))`	Cache Go build artifacts
`container.WithMountedCache("/root/.npm", dag.CacheVolume("npm"))`	Cache npm packages
`container.WithMountedCache("/root/.cargo/registry", dag.CacheVolume("cargo"))`	Cache Rust dependencies

Cache Busting

Command	Description
`container.WithEnvVariable("CACHE_BUSTER", time.Now().String())`	Bust cache when needed
`dagger call --focus=false build`	Run without automatic focus/caching
`container.WithoutEnvVariable("CACHE_BUSTER")`	Remove cache-busting variable

Secrets Management

Command	Description
`dag.SetSecret("token", os.Getenv("API_TOKEN"))`	Create secret from env variable
`container.WithSecretVariable("API_KEY", secret)`	Set env var from secret
`container.WithMountedSecret("/run/secrets/key", secret)`	Mount secret as file
`dagger call deploy --token=env:API_TOKEN`	Pass secret from env via CLI
`dagger call deploy --token=file:./token.txt`	Pass secret from file via CLI
`dagger call deploy --token=cmd:"vault read -field=token secret/app"`	Pass secret from command

Services

Service Binding

Command	Description
`container.WithServiceBinding("db", dbSvc)`	Bind a service to a container
`container.WithExposedPort(8080)`	Expose a port from a container
`container.AsService()`	Convert container into a service
`dag.Container().From("postgres:16").WithExposedPort(5432).AsService()`	Create a database service
`service.Start(ctx)`	Start a service explicitly
`service.Stop(ctx)`	Stop a running service

Service Binding Example

func (m *MyPipeline) IntegrationTest(ctx context.Context, src *dagger.Directory) (string, error) {
	postgres := dag.Container().
		From("postgres:16-alpine").
		WithEnvVariable("POSTGRES_PASSWORD", "test").
		WithEnvVariable("POSTGRES_DB", "testdb").
		WithExposedPort(5432).
		AsService()

	redis := dag.Container().
		From("redis:7-alpine").
		WithExposedPort(6379).
		AsService()

	return m.Build(ctx, src).
		WithServiceBinding("db", postgres).
		WithServiceBinding("cache", redis).
		WithEnvVariable("DATABASE_URL", "postgres://postgres:test@db:5432/testdb").
		WithEnvVariable("REDIS_URL", "redis://cache:6379").
		WithExec([]string{"go", "test", "-v", "-tags=integration", "./..."}).
		Stdout(ctx)
}

Multi-Stage Build Pattern

func (m *MyPipeline) BuildProduction(ctx context.Context, src *dagger.Directory) *dagger.Container {
	// Stage 1: Build dependencies
	deps := dag.Container().
		From("golang:1.22-alpine").
		WithDirectory("/src", src, dagger.ContainerWithDirectoryOpts{
			Include: []string{"go.mod", "go.sum"},
		}).
		WithWorkdir("/src").
		WithMountedCache("/go/pkg/mod", dag.CacheVolume("gomod")).
		WithExec([]string{"go", "mod", "download"})

	// Stage 2: Build binary
	build := deps.
		WithDirectory("/src", src).
		WithExec([]string{"go", "build", "-ldflags=-s -w", "-o", "/app/server", "./cmd/server"})

	// Stage 3: Minimal runtime
	return dag.Container().
		From("cgr.dev/chainguard/static:latest").
		WithFile("/app/server", build.File("/app/server")).
		WithExposedPort(8080).
		WithEntrypoint([]string{"/app/server"})
}

CI/CD Integration

GitHub Actions Integration

name: CI with Dagger
on:
  push:
    branches: [main]
  pull_request:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Install Dagger
        run: |
          curl -fsSL https://dl.dagger.io/dagger/install.sh | sh
          sudo mv ./bin/dagger /usr/local/bin/
      - name: Run pipeline
        env:
          DAGGER_CLOUD_TOKEN: ${{ secrets.DAGGER_CLOUD_TOKEN }}
        run: |
          dagger call build --source=.
          dagger call test --source=.
          dagger call lint --source=.
      - name: Publish
        if: github.ref == 'refs/heads/main'
        run: |
          dagger call publish --source=. --tag=${{ github.sha }}

GitLab CI Integration

stages:
  - build
  - test

variables:
  DAGGER_CLOUD_TOKEN: $DAGGER_CLOUD_TOKEN

build:
  stage: build
  image: alpine:latest
  before_script:
    - apk add curl
    - curl -fsSL https://dl.dagger.io/dagger/install.sh | sh
    - export PATH=$PWD/bin:$PATH
  script:
    - dagger call build --source=.
    - dagger call test --source=.

Debugging

Command	Description
`dagger call --debug build`	Run with debug logging
`dagger call build --interactive`	Drop into interactive shell on failure
`container.WithExec(["sh", "-c", "cat /etc/os-release"])`	Debug container contents
`container.Terminal()`	Open terminal in container (Go)
`export DAGGER_LOG_LEVEL=debug`	Set verbose logging
`dagger query '{ container { from(address:"alpine") { exec(args:["ls"]) { stdout } } } }'`	Debug with raw GraphQL
`dagger call build 2>&1 \| tee dagger-output.log`	Save output to log file
`container.WithExec(["ls", "-la", "/app"])`	List files for debugging
`container.WithExec(["env"])`	Print environment variables

Best Practices

Use cache volumes generously — mount caches for package managers (pip, npm, cargo, Go modules) to dramatically reduce build times across runs.
Keep modules small and composable — break large pipelines into reusable functions that each do one thing well, then compose them together.
Use secrets instead of environment variables — never pass sensitive values as plain strings; always use dag.SetSecret() or CLI secret references.
Pin base image versions — use specific tags like golang:1.22 instead of latest for reproducible builds.
Leverage multi-stage patterns — separate build dependencies from runtime to produce minimal final containers.
Use service bindings for integration tests — spin up databases, caches, and other dependencies as services instead of mocking them.
Export artifacts explicitly — use .Export() or .Publish() to make outputs available outside the Dagger engine.
Enable Dagger Cloud — connect to Dagger Cloud for pipeline caching, tracing, and collaborative debugging.
Use --interactive for debugging — when a step fails, --interactive drops you into the container at the failure point.
Test locally before CI — Dagger pipelines run identically on laptops and in CI, so validate everything locally first.