Get Started with Hasura DDN and an existing GraphQL API

Overview

This tutorial takes about twenty minutes to complete. You'll learn how to:

• Set up a new Hasura DDN project
• Connect it to an existing GraphQL API
• Generate Hasura metadata
• Create a build
• Run your first query

Additionally, we'll familiarize you with the steps and workflows necessary to iterate on your API.

This tutorial assumes you're starting with an existing GraphQL API to and connecting it to Hasura; for ease, we'll use the SpaceX API. Hasura will never modify your source schema.

Prerequisites

Install the DDN CLI

macOS and Linux

Simply run the installer script in your terminal:

curl -L https://graphql-engine-cdn.hasura.io/ddn/cli/v4/get.sh | bash

ARM-based Linux Machines

Currently, the CLI does not support installation on ARM-based Linux systems.

Windows

• Download the latest DDN CLI installer for Windows.
• Run the DDN_CLI_Setup.exe installer file and follow the instructions. This will only take a minute.
• By default, the DDN CLI is installed under C:\Users\{Username}\AppData\Local\Programs\DDN_CLI
• The DDN CLI is added to your %PATH% environment variable so that you can use the ddn command from your terminal.

Install Docker

The Docker based workflow helps you iterate and develop locally without deploying any changes to Hasura DDN, making the development experience faster and your feedback loops shorter. You'll need Docker Compose v2.20 or later.

Validate the installation

You can verify that the DDN CLI is installed correctly by running:

ddn doctor

Tutorial

Step 1. Authenticate your CLI

Before you can create a new Hasura DDN project, you need to authenticate your CLI:

ddn auth login

This will launch a browser window prompting you to log in or sign up for Hasura DDN. After you log in, the CLI will acknowledge your login, giving you access to Hasura Cloud resources.

Step 2. Scaffold out a new local project

Next, create a new local project:

ddn supergraph init my-project && cd my-project

Once you move into this directory, you'll see your project scaffolded out for you. You can view the structure by either running ls in your terminal, or by opening the directory in your preferred editor.

Step 3. Initialize your GraphQL connector

In your project directory, run:

ddn connector init my_graphql -i

From the dropdown, select hasura/graphql (you can type to filter the list), then hit enter to accept the default of all the options.

You'll be prompted for the API's endpoint:

Variable	Description	Example
GRAPHQL_ENDPOINT	The GraphQL endpoint for the existing API.	https://spacex-production.up.railway.app/

Enter the example endpoint above.

You can use different configurations for introspection and query execution

This environment variable will be written to the connector's configuration.json file. If you'd like to use a different configuration for introspection vs. executing requests, see the configuration docs here.

Step 4. Introspect your GraphQL endpoint

Next, use the CLI to introspect your GraphQL endpoint:

ddn connector introspect my_graphql

After running this, you should see a representation of your GraphQL API's schema in the app/connector/my_graphql/schema.graphql file; you can view this using cat or open the file in your editor.

Additionally, you can check which resources are available — and their status — at any point using the CLI:

ddn connector show-resources my_graphql

Step 5. Add your first command

The GraphQL connector exposes various top-level fields in an existing GraphQL API as commands.

Let's track single command from the existing API:

ddn command add my_graphql launches

Open the app/metadata directory and you'll find a newly-generated file: Launches.hml. The DDN CLI will use this Hasura Metadata Language file to represent the launches type from your GraphQL API in your supergraph as a command.

Step 6. Create a new build

To create a local build, run:

ddn supergraph build local

The build is stored as a set of JSON files in engine/build.

Step 7. Start your local services

Start your local Hasura DDN Engine and GraphQL connector:

ddn run docker-start

Your terminal will be taken over by logs for the different services.

Step 8. Run your first query

In a new terminal tab, open your local console:

ddn console --local

In the GraphiQL explorer of the console, write this query:

query GET_LAUNCH_DATA {
  launches {
    id
    missionName
  }
}

You'll get the following response:

{
  "data": {
    "launches": [
      {
        "id": "5eb87cd9ffd86e000604b32a",
        "missionName": "FalconSat"
      },
      {
        "id": "5eb87cdaffd86e000604b32b",
        "missionName": "DemoSat"
      },
      {
        "id": "5eb87cdbffd86e000604b32c",
        "missionName": "Trailblazer"
      },
      ...
    ]
  }
}

Step 9. Add another command

Let's add the command to query for rockets:

ddn command add my_graphql rockets

In app/connector/my_graphql/configuration.json, you'll see schema updated to include operations for the rockets GraphQL endpoint. In app/metadata/my_graphql.hml, you'll see rockets present in the metadata as well.

Step 10. Rebuild your project

Next, create a new build:

ddn supergraph build local

Bring down the services by pressing CTRL+C and start them back up:

ddn run docker-start

Step 11. Query your new build

Head back to your console and query the rockets:

query GET_ROCKETS_DATA {
  rockets {
    name
    costPerLaunch
    description
  }
}

You'll get a response like this:

{
  "data": {
    "rockets": [
      {
        "name": "Falcon 1",
        "costPerLaunch": 6700000,
        "description": "The Falcon 1 was an expendable launch system privately developed and manufactured by SpaceX during 2006-2009. On 28 September 2008, Falcon 1 became the first privately-developed liquid-fuel launch vehicle to go into orbit around the Earth."
      },
      {
        "name": "Falcon 9",
        "costPerLaunch": 50000000,
        "description": "Falcon 9 is a two-stage rocket designed and manufactured by SpaceX for the reliable and safe transport of satellites and the Dragon spacecraft into orbit."
      }
      ...
    ]
  }
}

create relationships to your own data

You can create relationships between resources in your connected GraphQL endpoint and data living in other data sources.

As an example, you may have a PostgreSQL database with a booster model exposed and which contains a unique id field. This field can be used to create a relationship between the rockets command and a booster in your database (or any other resource that utilizes a unique id) to return information across your sources in a single query.

Next steps

Congratulations on completing your first Hasura DDN project with an external GraphQL API! 🎉

Here's what you just accomplished:

• You started with a fresh project and connected it to an existing GraphQL API.
• You set up metadata to represent your existing GraphQL schema and how it integrates with your local Hasura project, which acts as the blueprint for your API.
• Then, you created a build — essentially compiling everything into a ready-to-use API — and successfully ran your first GraphQL queries to fetch data.
• Along the way, you learned how to iterate on your schema and refresh your metadata to reflect changes.

Now, you're equipped to connect and expose your data, empowering you to iterate and scale with confidence. Great work!

The GraphQL connector also supports mutations; you can create, update, or delete resources using your API.

Take a look at our GraphQL connector docs to learn more about how to use Hasura DDN with existing GraphQL APIs. Or, if you're ready, get started with adding permissions to control access to your API.