dagger/docs/learn/1003-get-started.md

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/1003/get-started/

Get Started with Dagger

In this tutorial, you will learn the basics of Dagger by building a Dagger project from scratch. This simple project deploys a React application to your local machine via docker. In later tutorials, you will learn how to configure Dagger to deploy to your infrastructure. And, for advanced users, how to share access to your infrastructure in the same way that we share access to ours now.

This tutorial does involve writing CUE, so if you haven’t already, be sure to read What is CUE?

In this tutorial we will learn:

• How to initialize and structure a Dagger project
• About Dagger concepts such as
  • the plan
  • environments
  • inputs and outputs
• How to write CUE for Dagger
• How to deploy an application using dagger up

Deploy an Application Locally

The following instructions assume you are working locally, but could just as easily be run on a remote machine into which you have a shell. For the sake of brevity and simplicity we will create directories under your home directory, but feel free to replace ~/ with a path that works best for you.

Install Dagger

First, make sure you have installed Dagger. You can run dagger version to ensure you have the latest installed and working.

Create a Dagger Project

First we need a directory that will contain our .cue files and a .dagger directory which stores metadata about environments. First, create a new directory for our todoapp, then initialize the project:

mkdir ~/todoapp
cd ~/todoapp
dagger init

If you now run ls -la you will see 2 new directories:

• The .dagger directory will store metadata about environments, inputs, and outputs which we will cover shortly.
• The cue.mod directory stores libraries such as dagger/universe which can be imported into your Dagger plan.

Dagger will load all .cue files recursively in the current Dagger project. More directories can be added to help organize code.

Note that Dagger, like the CUE CLI command, will only load CUE files from the cue.mod directory in response to import statements.

Write a Dagger Plan

A Dagger plan is written in CUE and expresses the resources, dependencies, and logic to deploy an application to an environment. Unlike traditional glue code written in an scripting language (e.g.: Bash, PowerShell), a Dagger plan is declarative rather than imperative. This frees us from thinking about order of operations, since Dagger will infer dependendencies and calculate correct order on its own.

First create a directory to hold our plan, separate from our application code:

mkdir ./plan

Next, create a file in plan/ called todoapp.cue with the following content

package todoapp

import (
	"alpha.dagger.io/dagger"
	"alpha.dagger.io/dagger/stream"
	"alpha.dagger.io/js/yarn"
)

// Source code of the sample application
source: dagger.#Artifact & dagger.#Input

// Build the source code using Yarn
app: yarn.#Package & {
	"source": source
}

Create an Environment

dagger new local -p ./plan
dagger list

Define Input Values per Environment

dagger input list

Input       Value             Set by user  Description
app.source  dagger.#Artifact  false        Application source code

dagger -e local input dir app.source ./app